Sustained hypophosphatemia after denosumab in a patient on hemodialysis

An 81-year-old Caucasian man who had commenced thrice weekly hemodialysis (HD) three months earlier, presented with a hip fracture, two vertebral fractures and a bone mineral density T-score of -3.6. He had received weekly iron sucrose infusions for 6 weeks and alphacalcidol on dialysis days. Although he suffered from coeliac disease and cirrhosis, he was fully ambulatory and well-nourished. He was normocalcaemic with a marginally low plasma phosphate and the PTH was 11.8 pmol/L (<2-times the upper range of the assay). In view of his severe osteoporosis, it was decided to treat him with denosumab (dmab). Laboratory assessment 2 weeks post dmab showed severe hypophosphatemia and hypocalcemia; phosphate 0.11 mmol/L and ionized calcium 0.83 mmol/L, and he was admitted for intravenous phosphate infusion. Three months later he remained on a phosphate supplement. The case illustrates that, in addition to the risks of hypocalcemia in patients with kidney failure and high bone turnover, kidney failure patients without evidence of high bone turnover, can also be at risk of hypocalcemia and severe hypophosphatemia requiring acute hospitalization and phosphate infusion. The potential role of compromised phosphate absorption versus increased deposition will be discussed. We recommend a cautious approach to dmab therapy in patients on dialysis, with evaluation of bone turnover and serum phosphate levels prior to initiation of treatment.

Calciphylaxis Episodes in the Australia and New Zealand Dialysis and Transplant Registry

Introduction

Calciphylaxis is a rare disorder associated with significant morbidity and mortality. Data registries are an invaluable source of information for rare diseases. We reviewed cases of calciphylaxis recorded in the Australia and New Zealand Dialysis and Transplant Registry (ANZDATA) and evaluated associations and outcomes of this condition.

Methods

Data was obtained on all cases of calciphylaxis reported between 2019 and 2022 in Australian and New Zealand patients on kidney replacement therapy (KRT). This cohort was compared to all patients in the registry who received KRT from 2019 to 2022 without an episode of calciphylaxis. Cox proportional hazards regression including a time-varying covariate for calciphylaxis episode was conducted for mortality with models restricted to patients on dialysis only.

Results

From 2019 to 2022, 333 patients had calciphylaxis episodes reported. Overall incidence rate for patients on dialysis was 4.5 (4.1-5.1) episodes per 1000 patient-years on dialysis. Median age was 63 (interquartile range [IQR]: 55-73) years, 54% were female, 66% had diabetes, 59% were obese (body mass index [BMI] ≥ 30 kg/m2) and 77% were receiving hemodialysis (HD) treatment. Compared to patients without calciphylaxis (n = 46,526), patients with calciphylaxis were more likely to be older, female, and have diabetes, greater BMI, coronary artery, and peripheral vascular disease. The median time to calciphylaxis was 3.2 (IQR: 0.9-6.7) years after KRT commencement. Half of the patients with calciphylaxis died by 12 months from diagnosis. Adjusted hazard ratio (HR) of mortality for patients on dialysis with calciphylaxis <1 year and 1 to 4 years after an episode was 5.8 (4.9-6.9) and 1.5 (1.0-2.1), respectively compared to patients on dialysis without calciphylaxis.

Conclusion

Calciphylaxis is a rare but life-threatening condition in people on KRT with the greatest mortality burden within 12 months of diagnosis.

Current Status of Mineral and Bone Disorders in Transplant Recipients

Most patients with end-stage kidney disease undergoing kidney transplantation are affected by the chronic kidney disease-mineral and bone disorder. This entity encompasses laboratory abnormalities, calcification of soft tissues, and the bone abnormalities of renal osteodystrophy that together result in an increased risk of fracture, cardiovascular events, and mortality. Although many biochemical disturbances associated with end-stage kidney disease improve in the first year after transplantation, hyperparathyroidism commonly persists, and residual changes of renal osteodystrophy are slow to resolve. When superimposed on common, traditional risk factors, post-transplant glucocorticoid treatment, the possibility of tubular disturbances and post-transplant chronic kidney disease, rates of incident fracture remain high. This review examines hormonal and biochemical changes before and after kidney transplantation, fracture risk assessment tools and imaging modalities, a staged approach to management and concerns associated with antiresorptive and anabolic therapies. A multidisciplinary approach is proposed as the best means to improve patient-level outcomes.

Chronic kidney disease-related sarcopenia as a prognostic indicator in elderly haemodialysis patients

BACKGROUND

The mortality of dialysis patients greatly exceeds that of the general population and identifying predictive factors for mortality may provide opportunities for earlier intervention. This study assessed the influence of sarcopenia on mortality in patients on haemodialysis.

METHODS

This prospective, observational study enrolled 77 haemodialysis patients aged 60 years and over, of whom 33 (43%) were female, from two community dialysis centres. Baseline demographic and laboratory data were collected, and sarcopenia was diagnosed using grip strength, muscle mass by bioimpedance analysis (BIA) and muscle function by timed up-and-go according to European Working Group on Sarcopenia in Older People criteria. Nutritional status was assessed using a subjective nutritional assessment score, comprising functional changes in weight, appetite, gastrointestinal symptoms and energy.. A comorbidity score (maximum 7 points) was derived from the presence or absence of hypertension, ischaemic heart disease, vascular disease (cerebrovascular disease, peripheral vascular disease, and abdominal aortic aneurysm), diabetes mellitus, respiratory disease, a history of malignancy and psychiatric disease. Outcomes over six years were linked to the Australian and New Zealand Dialysis and Transplant Registry.

RESULTS

The median participant age was 71 years (range 60-87). Probable and confirmed sarcopenia was present in 55.9% and severe sarcopenia with reduced functional testing in 11.7%. Over 6 years, overall mortality was 50 of the 77 patients (65%), principally from cardiovascular events, dialysis withdrawal and infection. There were no significant survival differences between patients with no, probable, confirmed, or severe sarcopenia, or between tertiles of the nutritional assessment score. After adjustment for age, dialysis vintage, mean arterial pressure (MAP) and the total comorbidity score, no sarcopenia category predicted mortality. However, the total comorbidity score [Hazard Ratio (HR) 1.27, Confidence Intervals (CI) 1.02, 1.58, p = 0.03] and MAP (HR 0.96, CI 0.94, 0.99, P = < 0.01) predicted mortality.

CONCLUSION

Sarcopenia is highly prevalent in elderly haemodialysis patients but is not an independent predictor of mortality. Haemodialysis patients have multiple competing risks for mortality which, in this study, was predicted by a lower MAP and a higher total comorbidity score.

TRIAL REGISTRATION

Recruitment commenced December 2011. The study was registered 10.01.2012 with the Australian New Zealand Clinical Trials Registry (ACTRN12612000048886).

DXA-derived advanced hip analysis and the trabecular bone score in end-stage kidney disease secondary to type 1 diabetes

OBJECTIVE

Patients with end-stage kidney disease (ESKD) caused by type 1 diabetes mellitus (T1DM) have a heightened fracture risk. Bone mineral density (BMD) may predict fracture less accurately in ESKD than in patients with chronic kidney disease (CKD) stages 1-3b or the general population. Alternate, readily available imaging modalities are needed to improve ESKD fracture risk assessment. This study aimed to assess dual-energy X-ray absorptiometry (DXA)-derived BMD, the trabecular bone score (TBS) and advanced hip analysis parameters in patients with ESKD due to T1DM and to compare their results with those of patients with ESKD from other causes.

METHODS

We compared the DXA-derived TBS, hip cortical thickness (CT) and femoral neck (FN) buckling ratio (BR), an index of FN stability, of patients with T1DM and ESKD undergoing simultaneous pancreas kidney transplantation, patients with ESKD from other causes receiving kidney transplants and population reference ranges.

RESULTS

Of 227 patients with ESKD, 28% had T1DM and 65% were male. Compared with other ESKD patients, patients with T1DM were younger (42 ± 7.7 vs 51 ± 13.8 years), had shorter dialysis duration (24.4 ± 21 vs 42.6 ± 40 months), had higher HbA1c (7.9 ± 1.57% vs 5.4 ± 0.95%) and had lower BMI (25 ± 6 vs 27 ± 5 kg/m2). They had lower spine, hip and UD radius BMD Z-scores (all P ≤ 0.001), TBS (1.33 ± 0.12 vs 1.36 ± 0.12; P = 0.05), CT at the FN (P = 0.03), calcar (P = 0.006) and shaft (P < 0.001) and higher BR (10.1±7.1 vs 7.7±4; P = 0.006). All ESKD parameters were lower than population-based reference ranges (P < 0.001). Adjusting for age, sex, dialysis vintage and weight, prevalent vertebral fractures in patients with T1DM and ESKD were associated with higher BR (odds ratio (OR): 3.27 (95% CI: 1.19-8.92), P = 0.002) and lower FN CT (OR: 3.70 (95% CI: 1.13-12.50)).

CONCLUSION

Patients with ESKD and T1DM have reduced TBS, reduced CT and increased BR compared with other ESKD patients. Prospective study of these parameters is warranted to determine their utility in fracture risk prediction and management.

SIGNIFICANCE STATEMENT

Patients with ESKD and T1DM have an elevated fracture risk due to decreased bone strength. As an adjunct to BMD, evaluating dual-energy X-ray absorptiometry parameters that incorporate structural change may have greater value in patients with ESKD and T1DM than in the general population. In this study, patients with ESKD due to T1DM had lower BMD, lower trabecular bone scores, more severe loss of CT and higher BR than other patients with ESKD and people from the general population. Both lower CT and higher BR were associated with prevalent vertebral fractures in patients with T1DM and ESKD. Changes to these parameters should be evaluated for incident fracture prediction.

Improving Bone Mineral Density Screening by using Digital X‐Radiogrammetry combined with Mammography

Fracture risk evaluation of postmenopausal women is suboptimal, but most women undergo screening mammography. Digital X‐radiogrammetry (DXR) determines bone mineral density (BMD) at the metacarpal shaft and can be performed on mammography equipment. This study examined correlations between DXR and dual‐energy X‐ray absorptiometry (DXA) in women undergoing mammography, to identify optimal DXR thresholds for triage to osteoporosis screening by central DXA. Postmenopausal women over age 50 years, recruited from Westmead Hospital's Breast Cancer Institute, underwent mammography, DXR and DXA. Agreements were determined using the area under the receiver operator characteristic (AUC ROC) curve and Lin's concordance correlation coefficient. Optimal DXR T‐scores to exclude osteoporosis by DXA were determined using the Youden's method. Of 200 women aged 64 ± 7 years (mean ± standard deviation [SD]), 82% had been diagnosed with breast cancer and 37% reported prior fracture. DXA T‐scores were ≤ −1 at the spine, hip or forearm in 77.5% and accorded with DXR T‐scores in 77%. For DXR and DXA T‐scores ≤ −2.5, the AUC ROC was 0.87 (95% confidence interval [CI], 0.81–0.94) at the 1/3 radius, and 0.74 (95% CI, 0.64–0.84) for hip or spine. DXR T‐scores > −1.98 provided a negative predictive value of 94% (range, 88%, 98%) for osteoporosis by central DXA. In response to a questionnaire, radiography staff responded that DXR added 5 minutes to patient throughput with minimal workflow impact. In the mammography setting, triaging women with a screening DXR T‐score < −1.98 for DXA evaluation would capture a significant proportion of at‐risk women who may not otherwise be identified and improve current low rates of osteoporosis screening. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Effect of lanthanum carbonate on serum calciprotein particles in patients with stage 3-4 CKD-results from a placebo-controlled randomized trial

BACKGROUND

Calciprotein particles (CPP) are colloidal aggregates of calcium phosphate and the mineral-binding protein fetuin-A, and are potential mediators of cardiovascular disease in chronic kidney disease (CKD). Emerging evidence suggests non-calcium-containing phosphate binders may reduce serum CPP in patients with kidney failure who require dialysis; however, it is unclear whether similar interventions are effective in patients with earlier stages of CKD.

METHODS

The IMpact of Phosphate Reduction On Vascular End-points in CKD (IMPROVE-CKD) was a multi-centre, placebo-controlled, randomized trial of lanthanum carbonate on cardiovascular markers in 278 participants with stage 3b/4 CKD. In this pre-specified exploratory analysis, primary (CPP-I) and secondary CPP (CPP-II) were measured in a sub-cohort of participants over 96 weeks. Treatment groups were compared using linear mixed-effects models and the relationship between serum CPP and pulse wave velocity (PWV) and abdominal aortic calcification (AAC) was examined.

RESULTS

A total of 253 participants had CPP data for baseline and at least one follow-up timepoint and were included in this analysis. The mean age was 62.4 ± 12.6 years, 32.0% were female and the mean estimated glomerular filtration rate (eGFR) was 26.6 ± 8.3 mL/min/1.73 m2. Baseline median serum CPP-I was 14.9 × 104 particles/mL [interquartile range (IQR) 4.6-49.3] and median CPP-II was 3.3 × 103 particles/mL (IQR 1.4-5.4). There was no significant difference between treatment groups at 96 weeks in CPP-I [22.8% (95% confidence interval -39.2, 36.4), P = 0.65] or CPP-II [-18.3% (95% confidence interval -40.0, 11.2), P = 0.20] compared with a placebo. Serum CPP were not correlated with baseline PWV or AAC, or with the progression of either marker.

CONCLUSIONS

Lanthanum carbonate was not associated with a reduction of CPP at 96 weeks when compared with a placebo in a CKD cohort.

Systematic Review and Meta-Analyses of the Effects of Phosphate-Lowering Agents in Nondialysis CKD

BACKGROUND

Benefits of phosphate-lowering interventions on clinical outcomes in patients with CKD are unclear; systematic reviews have predominantly involved patients on dialysis. This study aimed to summarize evidence from randomized controlled trials (RCTs) concerning benefits and risks of noncalcium-based phosphate-lowering treatment in nondialysis CKD.

METHODS

We conducted a systematic review and meta-analyses of RCTs involving noncalcium-based phosphate-lowering therapy compared with placebo, calcium-based binders, or no study medication, in adults with CKD not on dialysis or post-transplant. RCTs had ≥3 months follow-up and outcomes included biomarkers of mineral metabolism, cardiovascular parameters, and adverse events. Outcomes were meta-analyzed using the Sidik-Jonkman method for random effects. Unstandardized mean differences were used as effect sizes for continuous outcomes with common measurement units and Hedge's g standardized mean differences (SMD) otherwise. Odds ratios were used for binary outcomes. Cochrane risk of bias and GRADE assessment determined the certainty of evidence.

RESULTS

In total, 20 trials involving 2498 participants (median sample size 120, median follow-up 9 months) were eligible for inclusion. Overall, risk of bias was low. Compared with placebo, noncalcium-based phosphate binders reduced serum phosphate (12 trials, weighted mean difference -0.37; 95% CI, -0.58 to -0.15 mg/dl, low certainty evidence) and urinary phosphate excretion (eight trials, SMD -0.61; 95% CI, -0.90 to -0.31, low certainty evidence), but resulted in increased constipation (nine trials, log odds ratio [OR] 0.93; 95% CI, 0.02 to 1.83, low certainty evidence) and greater vascular calcification score (three trials, SMD, 0.47; 95% CI, 0.17 to 0.77, very low certainty evidence). Data for effects of phosphate-lowering therapy on cardiovascular events (log OR, 0.51; 95% CI, -0.51 to 1.17) and death were scant.

CONCLUSIONS

Noncalcium-based phosphate-lowering therapy reduced serum phosphate and urinary phosphate excretion, but there was an unclear effect on clinical outcomes and intermediate cardiovascular end points. Adequately powered RCTs are required to evaluate benefits and risks of phosphate-lowering therapy on patient-centered outcomes.

Relationship Between Dietary Phosphate Intake and Biomarkers of Bone and Mineral Metabolism in Australian Adults With Chronic Kidney Disease

OBJECTIVE

Higher serum phosphate is associated with increased adverse outcomes including cardiovascular disease. Abnormalities of bone and mineral metabolism in chronic kidney disease (CKD), including higher serum phosphate, are important risk factors for increased cardiovascular disease. Associations between dietary phosphate intake and biochemical and cardiovascular parameters in non-dialysis CKD patients, however, have not been adequately studied. This study aimed to explore associations between phosphate intake and biomarkers of bone and mineral metabolism and intermediate cardiovascular markers in adults with stage 3-4 CKD.

DESIGN AND METHODS

One hundred thirty-two participants enrolled in the IMpact of Phosphate Reduction On Vascular End-points in Chronic Kidney Disease trial were invited to participate in this sub-study. At baseline, dietary phosphate intake and its source (animal, plant, or a mixture of animal and plant) were determined using a 7-day self-administered diet food record, and measurements were made of serum and urinary phosphate, serum calcium, parathyroid hormone, fibroblast growth factor-23, and the intermediate cardiovascular markers pulse wave velocity (PWV) and abdominal aortic calcification. The relationships between dietary phosphate intake and these bone metabolism and cardiovascular markers were explored using Pearson's correlation and linear regression. The effect of source of phosphate intake was analyzed using compositional data analysis.

RESULTS

Ninety participants (age 64 ± 12 years, 68% male, estimated glomerular filtration rate 26.6 ± 7.6 mL/min/1.73 m², daily phosphate intake 1,544 ± 347 mg) completed the study. Correlations among dietary phosphate intake and biochemical measures, PWV, and abdominal aortic calcification ranged from r = -0.13 to r = +0.13. Linear regression showed no association between dietary phosphate measurements and biochemical or cardiovascular parameters. Source of phosphate intake was associated with PWV (P = .01), but not with other biomarkers of bone and mineral metabolism. Higher PWV values were associated with higher intake of plant-based relative to animal-based phosphate (1.058 [1.020-1.098], P = .003).

CONCLUSION

Levels of total dietary phosphate intake measured by dietary food record show no statistically significant relationship with biochemical markers of bone and mineral metabolism or intermediate cardiovascular markers. Higher PWV levels associated with higher intake of plant-based relative to animal-based phosphate intake were an unexpected finding and further research is needed in this area.

A review and perspective on the assessment, management and prevention of fragility fractures in patients with osteoporosis and chronic kidney disease

This article aims to review the methods used for the assessment of fracture risk and the use of osteoporosis medications for fracture prevention in the population with CKD, and highlights the difficulties faced by clinicians in the management of these patients and the latest recommendations and guidelines. Chronic kidney disease (CKD) and osteoporosis often co-exist in older adults, and they present a major healthcare challenge. CKD mineral and bone disorder (CKD-MBD) occurs as renal function declines and this syndrome affects most patients in CKD stages 4 and 5. The biochemical abnormalities of CKD-MBD, renal bone disease and risk factors associated with age-related bone loss and osteoporosis lead to a cumulative effect on fracture risk and mortality. There is a need for routine evaluation of fracture risk and fracture prevention in this population. Measurement of bone mineral density (BMD) and the use of the FRAX tool have predictive value for incident fractures in the general population and in CKD. This enables physicians to identify CKD patients most at risk of sustaining a fragility fracture and allows a more targeted approach to fracture prevention. Data analysis from the pivotal trials of therapeutic agents used in osteoporosis show that these drugs can be considered in mild and moderate CKD (stages 1-3 CKD). Off-label drug use in patients with CKD-MBD and more severe renal impairment (CKD stages 4 and 5) could offer significant benefits to sub-groups of patients when carefully tailored to each individual's bone turnover and calcium and phosphate balance. However, this requires a selective approach and treatment decisions based on inference from pathophysiology while we await further trials. Guidelines advocate the correction and/or reduction of the biochemical abnormalities of CKD-MBD before initiation of treatment with osteoporosis drugs and close monitoring during treatment.

Importance of bone turnover for therapeutic decisions in patients with CKD-MBD

Patients with chronic kidney disease-mineral and bone disorder (CKD-MBD) frequently have low bone formation rates. A recent review suggested that adynamic bone disease is not always associated with negative outcomes and therefore antiresorptive medications could be used more often. However, there is currently no evidence to support an improvement in fracture risk or mortality in patients with CKD-MBD and low bone turnover who are treated with antiresorptive medication. There is reasonable pathophysiological evidence suggesting that it may even be harmful.

The Australian Calciphylaxis Registry: reporting clinical features and outcomes of patients with calciphylaxis

BACKGROUND

Calciphylaxis is a rare disease, predominantly affecting patients with chronic kidney disease (CKD) and associated with significant morbidity and mortality due to progressive cutaneous calcification, necrotic ulceration and infection. Clinical registries have been established to better understand the risk factors, optimal treatments and disease outcomes of calciphylaxis.

METHODS

We established a prospective, Internet-based clinical registry for the online notification of calciphylaxis cases in Australia. Seven institutions participated, with data recorded on patient characteristics, biochemical parameters, treatments and disease outcomes.

RESULTS

Between 2014 and 2019, 47 cases of calciphylaxis were registered. The mean patient age was 66 ± 11 years and body mass index was 35 ± 9 kg/m2, with a higher proportion of females (51%). Eighty-seven percent of patients had end-stage kidney disease (ESKD), with 61% on hemodialysis or hemodiafiltration, with a median dialysis vintage of 4.8 [interquartile range (IQR) 1.7-7.4)] years. Five patients had CKD not requiring dialysis and two were kidney transplant recipients. Diabetes was present in 76% of patients and the cause of ESKD in 60%; 34% received vitamin K antagonists (VKAs) before diagnosis. The median parathyroid hormone level at diagnosis was 32 (IQR 14-50) pmol/L. The most common site of calciphylaxis was the lower limbs (63%), with 19% of patients having more than one area involved. Ten patients (22%) had a resolution of calciphylaxis and 25 died, with 50% mortality at a median of 1.6 (IQR 0.2-2.5) years from diagnosis.

CONCLUSIONS

The Australian Calciphylaxis Registry highlights risk factors for calciphylaxis, including diabetes, obesity and VKA use. Resolution of calciphylaxis is uncommon despite multimodal therapy and mortality from calciphylaxis in the first year following diagnosis remains high.

Patients with end-stage kidney disease have markedly abnormal cortical hip parameters by dual-energy X-ray absorptiometry

BACKGROUND

Patients with end-stage kidney disease (ESKD) have higher fracture rates and post-fracture mortality than the general population, but bone mineral density by dual-energy X-ray absorptiometry (DXA) is less predictive of fracture in this patient group. Bone biopsy and high-resolution imaging indicate that cortical thickness (CT) is reduced and cortical porosity is increased in ESKD. The aim of this study was to assess cortical parameters using DXA in patients with ESKD. It was hypothesized that these parameters would show deterioration and be associated with fracture.

METHODS

Using advanced hip analysis, normal age-related ranges were determined from 752 female and 861 male femur scans and were compared with scans of 226 patients with ESKD at the time of transplantation.

RESULTS

Compared with controls, female patients had lower mean±SD CT (mms) at the femoral neck (FN) (2.59 ± 1.42 versus 5.23 ± 1.85), calcar (3.46 ± 1.07 versus 5.09 ± 1.30) and shaft (4.42 ± 1.21 versus 7.44 ± 2.07; P < 0.001 for each), and buckling ratios were higher (8.21 ± 4.6 versus 3.63 ± 1.42; P < 0.001), indicating greater FN instability. All findings were similar for men. Prevalent fracture was documented in 28.8% of patients; 12.4% vertebral only, 8.4% non-vertebral only and 8% vertebral plus non-vertebral. In adjusted models, each 1 SD reduction in FN CT and increase in the buckling ratio was associated with a respective 1.73 (1.22-2.46)- and 1.82 (1.49-2.86)-fold increase in the risk of prevalent vertebral fracture.

CONCLUSIONS

In patients with ESKD, DXA-derived cortical parameters are markedly abnormal compared with age- and sex-matched controls. These parameters should be assessed for incident fracture prediction and targeting treatment.

How unmeasured muscle mass affects estimated GFR and diagnostic inaccuracy

BACKGROUND

Estimated glomerular filtration (eGFR) results based on serum creatinine are frequently inaccurate with differences against measured GFR (mGFR) often attributed to unmeasured non-functional factors, such as muscle mass.

METHODS

The influence of muscle mass (measured by dual-energy x-ray absorptiometry, DEXA) on eGFR error (eGFR-mGFR) was evaluated using isotopic mGFR (Tc^99m DTPA plasma clearance) in 137 kidney transplant recipients. Serum creatinine was measured by isotopic-calibrated enzymatic analysis, converted to eGFR using Chronic Kidney Disease EPIdemiology (CKD-EPI) formula, then unindexed from body surface area.

FINDINGS

Unindexed CKD-EPI eGFR error displayed absent fixed bias but modest proportional bias against reference mGFR. eGFR error correlated with total lean mass by DEXA (r=-0·350, P<0·001) and appendicular skeletal muscle index (ASMI), a proxy for muscularity (r=-0·420, P<0·001). eGFR was falsely reduced by -5·9 ± 1·4 mls/min per 10 kg lean mass. Adipose mass and percentage fat had no effect on error. Muscle-associated error varied with each eGFR formula and influenced all CKD stages. Systemic eGFR error was predicted by ASMI, mGFR, recipient age, and trimethoprim use using multivariable regression. Residual plots demonstrated heteroscedasticity and greater imprecision at higher mGFR levels (P<0·001), from increased variance corresponding to higher absolute values and unreliable prediction by serum creatinine of high mGFR. Serum creatinine correlated with ASMI independent of mGFR level (r = 0·416, P<0·001). The diagnostic test performance of CKD-EPI eGFR to predict CKD stage 3 (by mGFR) was weakest in cachexia (sensitivity 68·4%) and muscularity (specificity 47·4%, positive predictive value 54·5% for the highest ASMI quartile).

INTERPRETATION

Serum creatinine and eGFR are imperfect estimates of true renal function, with systemic errors from muscle mass, tubular secretion, and intrinsic proportional bias; and additional inaccuracy at the extremes of renal function and patient muscularity. Cautious interpretation of eGFR results in the context of body habitus and clinical condition is recommended.

Changes to bone mineral density, the trabecular bone score and hip structural analysis following parathyroidectomy: a case report

BACKGROUND

Reduction in bone mineral density (BMD) measured by dual-energy X-ray absorptiometry (DXA) occurs in secondary hyperparathyroidism associated with chronic kidney disease. BMD generally increases following parathyroidectomy, however longitudinal changes to other DXA-derived parameters, the trabecular bone score (TBS) and hip structural analysis (HSA), have not been described. Postoperative calcium requirements and positive calcium balance raise concerns for an increased risk of vascular calcification. This case illustrates the dramatic increase in BMD that can follow parathyroidectomy in a patient on dialysis, and for the first time demonstrates improvements to HSA parameters and to the TBS.

CASE PRESENTATION

A 30-year old woman on haemodialysis underwent subtotal parathyroidectomy for secondary hyperparathyroidism. She developed a post-operative 'hungry bone syndrome' requiring substantial calcium and calcitriol supplementation. Six months post-parathyroidectomy, BMD increased by 42% at the lumbar spine, 30% at the femoral neck and 25% at the total proximal femur, with increases sustained over the following 18 months. The TBS increased by 8%. HSA showed a 63% increase in femoral neck cortical thickness and 38% reduction in the buckling ratio, consistent with increased femoral neck stability. The abdominal aortic vascular calcification score (0-24) increased from zero 8-years pre-parathyroidectomy to 2/24 at 18-months post-parathyroidectomy.

CONCLUSION

BMD losses incurred by secondary hyperparathyroidism recover rapidly after parathyroidectomy, particularly at sites of trabecular bone. Bone architectural parameters, measured as the TBS and by HSA, also improve. Greater BMD gains may be associated with higher post-operative calcium requirements. While bone is the major reservoir for post-parathyroidectomy calcium supplementation, positive calcium balance may contribute to vascular calcification risk.

A Randomized Trial on the Effect of Phosphate Reduction on Vascular End Points in CKD (IMPROVE-CKD)

BACKGROUND

Hyperphosphatemia is associated with increased fibroblast growth factor 23 (FGF23), arterial calcification, and cardiovascular mortality. Effects of phosphate-lowering medication on vascular calcification and arterial stiffness in CKD remain uncertain.

METHODS

To assess the effects of non-calcium-based phosphate binders on intermediate cardiovascular markers, we conducted a multicenter, double-blind trial, randomizing 278 participants with stage 3b or 4 CKD and serum phosphate >1.00 mmol/L (3.10 mg/dl) to 500 mg lanthanum carbonate or matched placebo thrice daily for 96 weeks. We analyzed the primary outcome, carotid-femoral pulse wave velocity, using a linear mixed effects model for repeated measures. Secondary outcomes included abdominal aortic calcification and serum and urine markers of mineral metabolism.

RESULTS

A total of 138 participants received lanthanum and 140 received placebo (mean age 63.1 years; 69% male, 64% White). Mean eGFR was 26.6 ml/min per 1.73 m2; 45% of participants had diabetes and 32% had cardiovascular disease. Mean serum phosphate was 1.25 mmol/L (3.87 mg/dl), mean pulse wave velocity was 10.8 m/s, and 81.3% had abdominal aortic calcification at baseline. At 96 weeks, pulse wave velocity did not differ significantly between groups, nor did abdominal aortic calcification, serum phosphate, parathyroid hormone, FGF23, and 24-hour urinary phosphate. Serious adverse events occurred in 63 (46%) participants prescribed lanthanum and 66 (47%) prescribed placebo. Although recruitment to target was not achieved, additional analysis suggested this was unlikely to have significantly affected the principle findings.

CONCLUSIONS

In patients with stage 3b/4 CKD, treatment with lanthanum over 96 weeks did not affect arterial stiffness or aortic calcification compared with placebo. These findings do not support the role of intestinal phosphate binders to reduce cardiovascular risk in patients with CKD who have normophosphatemia.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

Australian Clinical Trials Registry, ACTRN12610000650099.

Radiographic absorptiometry: a step in solving the CKD fracture puzzle

Patients on dialysis are highly prone to fracture, and radiographic absorptiometry can be used to measure their bone mineral density and assess fracture risk. However, to determine its place in management, radiographic absorptiometry should be compared with dual-energy X-ray absorptiometry, and with fracture risk assessment tools such as FRAX, tests of muscle strength, biomarkers, and newer dual-energy X-ray absorptiometry techniques. The convenience, accessibility, and cost of radiographic absorptiometry may contribute to its utility in a number of clinical settings.

Dietary Phosphate Consumption in Australians With Stages 3b and 4 Chronic Kidney Disease

OBJECTIVE

Dietary phosphate modification is a common therapy to treat hyperphosphatemia in individuals with chronic kidney disease (CKD). However, current dietary intake and common food sources of phosphate typically consumed by individuals with CKD are not well characterized. This study examined a cohort of CKD patients to determine total dietary intake and common food sources of phosphate, including phosphate additives.

DESIGN AND METHODS

Participants with CKD stages 3b and 4 recruited to a substudy of the "IMPROVE-CKD (IMpact of Phosphate Reduction On Vascular End-points in Chronic Kidney Disease) Study" completed a 7-day self-administered diet record at baseline. Diet histories were analyzed and daily phosphate intakes determined using FoodWorks V.9 (Xyris). The proportion of phosphate contributed by each food group was determined using the AUSNUT 2011-2013 Food Classification System. Ingredient lists of packaged food items consumed were reviewed to determine frequency of phosphate-based additives.

RESULTS

Ninety participants (mean eGFR 26.5 mL/min/1.73 m²) completed this substudy. Mean phosphate intake of participants was 1544 ± 347 mg/day, with 96% of individuals exceeding the recommended daily intake of phosphate (1000 mg/day). The highest sources of dietary phosphate were milk-based products (25%) and meat and poultry products/dishes (25%). Phosphate-based food additives were identified in 39% (n = 331/845) of packaged foods consumed by participants.

CONCLUSION

Dietary phosphate intakes of Australians with CKD are high and come from a variety of sources. Managing dietary phosphate intake requires a patient-centered, tailored approach with an emphasis on maintaining nutritional adequacy and awareness of phosphate additives.

Aortic Calcification and Arterial Stiffness Burden in a Chronic Kidney Disease Cohort with High Cardiovascular Risk: Baseline Characteristics of the Impact of Phosphate Reduction On Vascular End-Points in Chronic Kidney Disease Trial

Chronic kidney disease (CKD) is associated with excess cardiovascular morbidity and mortality compared to the general population. Hyperphosphataemia, associated with vascular calcification and arterial stiffness, may play a key role in the pathogenesis of cardiovascular disease (CVD) associated with CKD, although phosphate reduction strategies have not consistently proven to beneficially affect clinically relevant outcomes. The IMpact of Phosphate Reduction On Vascular End-points in CKD (IMPROVE-CKD) study is an international, multi-centre, randomized, placebo-controlled trial investigating the effect of the phosphate binder lanthanum carbonate on intermediate cardiovascular markers in patients with stage 3b-4 CKD. The primary end-point is change in carotid-femoral pulse wave velocity (PWV, SphygmoCor) after 96 weeks. Secondary outcomes include change in abdominal aortic calcification (AAC, computed tomography), serum phosphate and fibroblast growth factor 23 (FGF-23). In total, 278 participants were recruited and randomized, mean age 63 ± 13 years, 69% male, 45% diabetes, 32% CVD, 33% stage 3b CKD and 67% stage 4 CKD. Mean estimated glomerular filtration rate and serum phosphate were 26.6 ± 8.3 mL/min/1.72 m2 and 1.25 ± 0.20 mmol/L, respectively. Median (interquartile range) intact and c-terminal FGF-23 levels were 133.0 (89.1-202) pg/mL and 221.1 (154.3-334.1) RU/mL, respectively. Mean PWV was 10.8 ± 3.6 m/s and 81% had AAC (median Agatston score 1,535 [63-5,744] Hounsfield units). PWV ≥10 m/s was associated with older age, diabetes, CVD, presence of AAC, higher systolic blood pressure (BP), larger waist circumference and higher alkaline phosphatase. AAC was associated with older age, male sex, diabetes, CVD, higher diastolic BP, dyslipidaemia (and use of statins), smoking, larger waist circumference and increased PWV. In conclusion, IMPROVE-CKD participants had high baseline risk for cardiovascular events, as suggested by high baseline PWV and AAC values.

Outcomes of cinacalcet withdrawal in Australian dialysis patients

BACKGROUND

Secondary hyperparathyroidism (SHPT) in chronic kidney disease is associated with cardiovascular and bone pathology. Measures to achieve parathyroid hormone (PTH) target values and control biochemical abnormalities associated with SHPT require complex therapies, and severe SHPT often requires parathyroidectomy or the calcimimetic cinacalcet. In Australia, cinacalcet was publicly funded for dialysis patients from 2009 to 2015 when funding was withdrawn following publication of the EVOLVE study, which resulted in most patients on cinacalcet ceasing therapy. We examined the clinical and biochemical outcomes associated with this change at Australian renal centres.

AIM

To assess changes to biochemical and clinical outcomes in dialysis patients following cessation of cinacalcet.

METHODS

We conducted a retrospective study of dialysis patients who ceased cinacalcet after August 2015 in 11 Australian units. Clinical outcomes and changes in biochemical parameters were assessed over a 24- and 12-month period, respectively, from cessation of cinacalcet.

RESULTS

A total of 228 patients was included (17.7% of all dialysis patients from the units). Patients were aged 63 ± 15 years with 182 patients on haemodialysis and 46 on peritoneal dialysis. Over 24 months following cessation of cinacalcet, we observed 26 parathyroidectomies, 3 episodes of calciphylaxis, 8 fractures and 50 deaths. Eight patients recommenced cinacalcet, meeting criteria under a special access scheme. Biochemical changes from baseline to 12 months after cessation included increased levels of serum PTH from 54 (interquartile range 27-90) pmol/L to 85 (interquartile range 41-139) pmol/L (P < 0.0001), serum calcium from 2.3 ± 0.2 mmol/L to 2.5 ± 0.1 mmol/L (P < 0.0001) and alkaline phosphatase from 123 (92-176) IU/L to 143 (102-197) IU/L (P < 0.0001).

CONCLUSION

Significant increases in serum PTH, calcium and alkaline phosphatase occurred over a 12-month period following withdrawal of cinacalcet. Longer-term follow up will determine if these biochemical and therapeutic changes are associated with altered rates of parathyroidectomies and cardiovascular mortality and morbidity.

Laparoscopic partial nephrectomy for Juxtaglomerular apparatus tumour: A rare cause of hypertension

We report on the case of a partial nephrectomy for a Juxtaglomerular apparatus (JGA) tumour in a 28 year old female who presented with fatigue and symptomatic hypertension, and a normal serum renin level on pre-operative work-up.

Association between Aortic Calcification, Cardiovascular Events, and Mortality in Kidney and Pancreas-Kidney Transplant Recipients

BACKGROUND

Cardiovascular (CV) disease is the leading cause of death in kidney and simultaneous pancreas-kidney (SPK) transplant recipients. Assessing abdominal aortic calcification (AAC), using lateral spine x-rays and the Kaupilla 24-point AAC (0-24) score, may identify transplant recipients at higher CV risk.

METHODS

Between the years 2000 and 2015, 413 kidney and 213 SPK first transplant recipients were scored for AAC at time of transplant and then followed for CV events (coronary heart, cerebrovascular, or peripheral vascular disease), graft-loss, and all-cause mortality.

RESULTS

The mean age was 44 ± 12 years (SD) with 275 (44%) having AAC (26% moderate: 1-7 and 18% high: ≥8). After a median of 65 months (IQR 29-107 months), 46 recipients experienced CV events, 59 died, and 80 suffered graft loss. For each point increase in AAC, the unadjusted hazard ratios (HR) for CV events and mortality were 1.11 (95% CI 1.07-1.15) and 1.11 (1.08-1.15). These were similar after adjusting for age, gender, smoking, transplant type, dialysis vintage, and diabetes: aHR 1.07 (95% CI 1.02-1.12) and 1.09 (1.04-1.13). For recipients with high versus no AAC, the unadjusted and fully-adjusted HRs for CV events were 5.90 (2.90-12.02) and 3.51 (1.54-8.00), for deaths 5.39 (3.00-9.68) and 3.38 (1.71-6.70), and for graft loss 1.30 (0.75-2.28) and 1.94 (1.04-3.27) in age and smoking history-adjusted analyses.

CONCLUSION

Kidney and SPK transplant recipients with high AAC have 3-fold higher CV and mortality risk and poorer graft outcomes than recipients without AAC. AAC scoring may be useful in assessing and targeted risk-lowering strategies.

Role of dietary phosphate restriction in chronic kidney disease

AIM

Patients with progressive chronic kidney disease (CKD) develop positive phosphate balance that is associated with increased cardiovascular risk and mortality. Modification of dietary phosphate is a commonly used strategy to improve outcomes but is complicated by the need for adequate dietary protein. Surprisingly, the evidence for patient-level benefits from phosphate restriction is tenuous, and the justification for using any phosphate binder for pre-dialysis patients is questionable.

METHODS

The evidence for dietary phosphate modification was reviewed, along with the possible role of a smart phone application (app) that provides information on phosphate, sodium, potassium and nutrients in over 50 000 Australian foods. A pilot study of healthy participants assigned to dietetic advice and standard diet sheets, or dietetic advice, diet sheets and use of the smart phone app was performed.

RESULTS

Following baseline studies, 25 participants commenced the sodium and phosphate restricted diet. After 2 weeks, both groups showed non-significant trends to reduction in urinary phosphate and sodium. App users referred to information on the app more frequently than the control group participants referred to written instructions, found referring to the app more convenient, felt they learned more new information, were more motivated to maintain the diet and were more likely to recommend their information source to family or friends (all P < 0.05).

CONCLUSIONS

Maintaining phosphate balance remains an important goal of CKD management, although diets incorporating very low phosphate and protein contents may worsen patient outcomes. For selected patients, a smart phone app may improve dietary acceptance and compliance.

Acute hypocalcaemia following denosumab in heart and lung transplant patients with osteoporosis

BACKGROUND

Osteoporosis is highly prevalent in the heart and lung transplant population. Given high rates of concurrent renal impairment, there is increasing use of denosumab in this population. However, denosumab may be associated with hypocalcaemia, particularly in patients with chronic kidney disease (CKD).

AIM

To explore the risk of hypocalcaemia in a heart and lung transplant cohort prescribed denosumab for osteoporosis.

METHODS

We performed a retrospective database review of all surviving heart and lung transplant patients who had received denosumab for osteoporosis between January 2012 and November 2015. We assessed the rates of hypocalcaemia in this cohort and collected baseline clinical data to determine associated factors.

RESULTS

Ten patients received denosumab and had laboratory results available within 3 months of the dose. Of these, three patients developed severe (grade 4) hypocalcaemia, while two patients developed mild (grade 1) hypocalcaemia. In comparison to the five patients who remained normocalcaemic, patients with hypocalcaemia had significantly lower baseline mean estimated glomerular filtration rate but similar baseline mean corrected serum calcium. Unexpectedly, patients developing hypocalcaemia had non-significantly higher levels of 25-hydroxyvitamin D and lower baseline doses of prednisone.

CONCLUSIONS

In heart and lung transplant patients, denosumab should be used judiciously in patients with advanced renal disease due to the risk of hypocalcaemia.

Magnetic resonance imaging based assessment of bone microstructure as a non-invasive alternative to histomorphometry in patients with chronic kidney disease

BACKGROUND

Chronic kidney disease (CKD) adversely affects bone microarchitecture and increases fracture risk. Historically, bone biopsy has been the 'gold standard' for evaluating renal bone disease but is invasive and infrequently performed. High-resolution magnetic resonance imaging (MRI) quantifies bone microarchitecture noninvasively. In patients with CKD, it has not been compared with results derived from bone biopsy or with imaging using dual energy X-ray absorptiometry (DXA).

METHODS

Fourteen patients with end-stage kidney disease (ESKD) underwent MRI at the distal tibia, bone mineral density (BMD) by dual energy X-ray absorptiometry (DXA; hip and spine) and transiliac bone biopsies with histomorphometry and microcomputed tomography (micro-CT). All patients had biomarkers of mineral metabolism. Associations were determined by Spearman's or Pearson's rank correlation coefficients.

RESULTS

MRI indices of trabecular network integrity, surface to curve ratio (S/C) and erosion index (EI), correlated to histomorphometric trabecular bone volume (S/C r = 0.85, p = 0.0003; EI r = -0.82, p = 0.001), separation (S/C r = -0.58, p = 0.039; EI r = 0.79, p = 0.0012) and thickness (S/C, r = 0.65, p = 0.017). MRI EI and trabecular thickness (TbTh) also correlated to micro-CT trabecular separation (EI r = 0.63, p = 0.02; TbTh r = -0.60, p = 0.02). Significant correlations were observed between histomorphometric mineralization and turnover indices and various MRI parameters. MRI-derived trabecular parameters were also significantly related to femoral neck BMD.

CONCLUSIONS

This study highlights the heterogeneity of bone microarchitecture at differing skeletal sites. MRI demonstrates significant, relevant associations to important bone biopsy and DXA indices and warrants further investigation to assess its potential to non-invasively evaluate changes in bone structure and quality over time.

Phosphate binders for preventing and treating chronic kidney disease-mineral and bone disorder (CKD-MBD)

BACKGROUND

Phosphate binders are used to reduce positive phosphate balance and to lower serum phosphate levels for people with chronic kidney disease (CKD) with the aim to prevent progression of chronic kidney disease-mineral and bone disorder (CKD-MBD). This is an update of a review first published in 2011.

OBJECTIVES

The aim of this review was to assess the benefits and harms of phosphate binders for people with CKD with particular reference to relevant biochemical end-points, musculoskeletal and cardiovascular morbidity, hospitalisation, and death.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 12 July 2018 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) or quasi-RCTs of adults with CKD of any GFR category comparing a phosphate binder to another phosphate binder, placebo or usual care to lower serum phosphate. Outcomes included all-cause and cardiovascular death, myocardial infarction, stroke, adverse events, vascular calcification and bone fracture, and surrogates for such outcomes including serum phosphate, parathyroid hormone (PTH), and FGF23.

DATA COLLECTION AND ANALYSIS

Two authors independently selected studies for inclusion and extracted study data. We applied the Cochrane 'Risk of Bias' tool and used the GRADE process to assess evidence certainty. We estimated treatment effects using random-effects meta-analysis. Results were expressed as risk ratios (RR) for dichotomous outcomes together with 95% confidence intervals (CI) or mean differences (MD) or standardised MD (SMD) for continuous outcomes.

MAIN RESULTS

We included 104 studies involving 13,744 adults. Sixty-nine new studies were added to this 2018 update.Most placebo or usual care controlled studies were among participants with CKD G2 to G5 not requiring dialysis (15/25 studies involving 1467 participants) while most head to head studies involved participants with CKD G5D treated with dialysis (74/81 studies involving 10,364 participants). Overall, seven studies compared sevelamer with placebo or usual care (667 participants), seven compared lanthanum to placebo or usual care (515 participants), three compared iron to placebo or usual care (422 participants), and four compared calcium to placebo or usual care (278 participants). Thirty studies compared sevelamer to calcium (5424 participants), and fourteen studies compared lanthanum to calcium (1690 participants). No study compared iron-based binders to calcium. The remaining studies evaluated comparisons between sevelamer (hydrochloride or carbonate), sevelamer plus calcium, lanthanum, iron (ferric citrate, sucroferric oxyhydroxide, stabilised polynuclear iron(III)-oxyhydroxide), calcium (acetate, ketoglutarate, carbonate), bixalomer, colestilan, magnesium (carbonate), magnesium plus calcium, aluminium hydroxide, sucralfate, the inhibitor of phosphate absorption nicotinamide, placebo, or usual care without binder. In 82 studies, treatment was evaluated among adults with CKD G5D treated with haemodialysis or peritoneal dialysis, while in 22 studies, treatment was evaluated among participants with CKD G2 to G5. The duration of study follow-up ranged from 8 weeks to 36 months (median 3.7 months). The sample size ranged from 8 to 2103 participants (median 69). The mean age ranged between 42.6 and 68.9 years.Random sequence generation and allocation concealment were low risk in 25 and 15 studies, respectively. Twenty-seven studies reported low risk methods for blinding of participants, investigators, and outcome assessors. Thirty-one studies were at low risk of attrition bias and 69 studies were at low risk of selective reporting bias.In CKD G2 to G5, compared with placebo or usual care, sevelamer, lanthanum, iron and calcium-based phosphate binders had uncertain or inestimable effects on death (all causes), cardiovascular death, myocardial infarction, stroke, fracture, or coronary artery calcification. Sevelamer may lead to constipation (RR 6.92, CI 2.24 to 21.4; low certainty) and lanthanum (RR 2.98, CI 1.21 to 7.30, moderate certainty) and iron-based binders (RR 2.66, CI 1.15 to 6.12, moderate certainty) probably increased constipation compared with placebo or usual care. Lanthanum may result in vomiting (RR 3.72, CI 1.36 to 10.18, low certainty). Iron-based binders probably result in diarrhoea (RR 2.81, CI 1.18 to 6.68, high certainty), while the risks of other adverse events for all binders were uncertain.In CKD G5D sevelamer may lead to lower death (all causes) (RR 0.53, CI 0.30 to 0.91, low certainty) and induce less hypercalcaemia (RR 0.30, CI 0.20 to 0.43, low certainty) when compared with calcium-based binders, and has uncertain or inestimable effects on cardiovascular death, myocardial infarction, stroke, fracture, or coronary artery calcification. The finding of lower death with sevelamer compared with calcium was present when the analysis was restricted to studies at low risk of bias (RR 0.50, CI 0.32 to 0.77). In absolute terms, sevelamer may lower risk of death (all causes) from 210 per 1000 to 105 per 1000 over a follow-up of up to 36 months, compared to calcium-based binders. Compared with calcium-based binders, lanthanum had uncertain effects with respect to all-cause or cardiovascular death, myocardial infarction, stroke, fracture, or coronary artery calcification and probably had reduced risks of treatment-related hypercalcaemia (RR 0.16, CI 0.06 to 0.43, low certainty). There were no head-to-head studies of iron-based binders compared with calcium. The paucity of placebo-controlled studies in CKD G5D has led to uncertainty about the effects of phosphate binders on patient-important outcomes compared with placebo.It is uncertain whether the effects of binders on clinically-relevant outcomes were different for patients who were and were not treated with dialysis in subgroup analyses.

AUTHORS' CONCLUSIONS

In studies of adults with CKD G5D treated with dialysis, sevelamer may lower death (all causes) compared to calcium-based binders and incur less treatment-related hypercalcaemia, while we found no clinically important benefits of any phosphate binder on cardiovascular death, myocardial infarction, stroke, fracture or coronary artery calcification. The effects of binders on patient-important outcomes compared to placebo are uncertain. In patients with CKD G2 to G5, the effects of sevelamer, lanthanum, and iron-based phosphate binders on cardiovascular, vascular calcification, and bone outcomes compared to placebo or usual care, are also uncertain and they may incur constipation, while iron-based binders may lead to diarrhoea.

Changes in bone microarchitecture following kidney transplantation-Beyond bone mineral density

Bone disease in kidney transplant recipients (KTRs) is characterized by bone mineral density (BMD) loss but bone microarchitecture changes are poorly defined. In this prospective cohort study, we evaluated bone microarchitecture using non-invasive imaging modalities; high-resolution magnetic resonance imaging (MRI), peripheral quantitative computed tomography (pQCT), dual energy X-ray absorptiometry (DXA), and the trabecular bone score (TBS) following kidney transplantation. Eleven KTRs (48.3 ± 11.2 years) underwent MRI (tibia), pQCT (radius) and DXA at baseline and 12 months post-transplantation. Transiliac bone biopsies, performed at transplantation, showed 70% of patients with high/normal bone turnover. Compared with baseline, 12-month MRI showed deterioration in indices of trabecular network integrity-surface to curve ratio (S/C; -15%, P = 0.03) and erosion index (EI; +19%, P = 0.01). However, cortical area increased (+10.3%, P = 0.04), with a non-significant increase in cortical thickness (CtTh; +7.8%, P = 0.06). At 12 months, parathyroid hormone values (median 10.7 pmol/L) correlated with improved S/C (r = 0.75, P = 0.009) and EI (r = -0.71, P = 0.01) while osteocalcin correlated with CtTh (r = 0.72, P = 0.02) and area (r = 0.70, P = 0.02). TBS decreased from baseline (-5.1%, P = 0.01) with no significant changes in BMD or pQCT. These findings highlight a post-transplant deterioration in trabecular bone quality detected by MRI and TBS, independent of changes in BMD, underlining the potential utility of these modalities in evaluating bone microarchitecture in KTRs.

Aortic vascular calcification is inversely associated with the trabecular bone score in patients receiving dialysis

INTRODUCTION

Progressive chronic kidney disease (CKD) confers a marked increase in risk for vascular calcification, cardiovascular disease, fracture and mortality, with likely contributing factors including dysregulated bone metabolism and mineral homeostasis. In general population studies, increased vascular calcification is directly related to mortality and inversely related to bone mineral density (BMD) measured by dual-energy X-ray absorptiometry (DXA). In patients with CKD, abnormalities in turnover, mineralization and bone volume reduce the ability of DXA to predict fracture. The trabecular bone score (TBS) obtained from lumbar spine DXA images, provides a surrogate measure of microarchitectural integrity not captured by BMD. This study aimed to examine the association of the TBS to prevalent abdominal aortic calcification (AAC) in patients with CKD receiving dialysis.

METHODS

We performed a cross-sectional study of dialysis patients awaiting transplantation. All patients underwent laboratory testing, lateral spinal radiographs including the abdominal aorta, DXA imaging and TBS assessment. AAC scores were determined using the Kauppila method. Correlations and linear regression models were used to determine predictors of AAC scores.

RESULTS

146 patients (60% male, mean age 48 ± 13 years) were included, of whom 49% had prevalent calcification with an AAC score ≥ 1. Of those with calcification, the mean AAC score was 7 ± 5.5 and 42 patients had scores ≥ 6, considered to indicate severe AAC. TBS values corresponding to intermediate or high risk for fracture (<1.31) were present in 35% of patients. TBS values correlated inversely to AAC scores (β = -0.206, p = 0.013) and remained significant in multivariable linear regression, adjusting for age, BMI and time on dialysis (-0.160, p = 0.031). There was no significant correlation of AAC scores to any BMD parameter.

CONCLUSION

There is a high prevalence of AAC in relatively young dialysis patients awaiting transplantation and their AAC scores are inversely related to the TBS but not to DXA-derived BMD parameters. In patients with CKD on dialysis, TBS assessment reflects microarchitectural abnormalities of bone not captured by DXA. The inverse relationship of TBS to vascular calcification may provide insights into bone-vascular interactions in CKD.

The trabecular bone score is associated with bone mineral density, markers of bone turnover and prevalent fracture in patients with end stage kidney disease

Fracture risk increases in end-stage kidney disease (ESKD), but bone mineral density (BMD) measurement is less predictive of risk than in the general population. In this study of patients with ESKD, a lower trabecular bone score (TBS), indicative of microarchitectural deterioration, was associated with higher bone turnover markers and prevalent non-vertebral fracture.

INTRODUCTION

Declining renal function carries increased fracture risks, but BMD is less predictive of fracture for dialysis patients than the general population. The TBS, obtained from lumbar spine dual-energy X-ray absorptiometry (DXA) images, provides information on microarchitectural integrity not captured by BMD. The aim of this study was to assess associations of the TBS to clinical, DXA, radiological, and laboratory measures in patients with ESKD undergoing kidney and simultaneous pancreas kidney (SPK) transplantation.

METHODS

A total of 147 patients with ESKD underwent pre-transplant laboratory testing, DXA, lateral spine X-ray, and structured history within 4 weeks of transplantation. Associations of the TBS to demographic data, prevalent fracture, BMD, and laboratory variables were assessed.

RESULTS

Of 147 patients (60% male, mean age 48 ± 13 years), 36% had diabetes mellitus (DM) and 54 patients had fractures: 21 prevalent vertebral fractures only, 22 non-vertebral fractures only, and 11 had both. The mean TBS (1.345 ± 0.125) was lower in patients undergoing SPK than kidney-only transplants (1.292 vs. 1.364, p = 0.001). The TBS correlated to spine and total hip BMD, body mass index and inversely to parathyroid hormone, alkaline phosphatase and procollagen 1 N-propeptide. By multivariable logistic regression, lower TBS was significantly associated to prior non-vertebral fracture (p = 0.026).

CONCLUSIONS

A lower TBS, suggestive of increased microarchitectural damage, was associated with type 1 DM, markers of higher bone turnover, and prevalent fracture. These data support the need for prospective studies to evaluate whether TBS inclusion improves fracture prediction in patients with ESKD.

Deterioration of Cortical Bone Microarchitecture: Critical Component of Renal Osteodystrophy Evaluation

BACKGROUND

Cortical bone is a significant determinant of bone strength and its deterioration contributes to bone fragility. Thin cortices and increased cortical porosity have been noted in patients with chronic kidney disease (CKD), but the "Turnover Mineralization Volume" classification of renal osteodystrophy does not emphasize cortical bone as a key parameter. We aimed to assess trabecular and cortical bone microarchitecture by histomorphometry and micro-CT in patients with CKD G5 and 5D (dialysis).

METHODS

Transiliac bone biopsies were performed in 14 patients undergoing kidney transplantation (n = 12) and parathyroidectomy (n = 2). Structural parameters were analysed by histomorphometry and micro-CT including trabecular bone volume, thickness (TbTh), number (TbN) and separation and cortical thickness (CtTh) and porosity (CtPo). Indices of bone remodelling and mineralisation were obtained and relationships to bone biomarkers examined. Associations were determined by Spearman's or Pearson's rank correlation coefficients.

RESULTS

By micro-CT, trabecular parameters were within normal ranges in most patients, but all patients showed very low CtTh (127 ± 44 µm) and high CtPo (60.3 ± 22.5%). CtPo was inversely related to TbN (r = -0.56; p = 0.03) by micro-CT and to TbTh (r = -0.60; p = 0.024) by histomorphometry and correlated to parathyroid hormone values (r = 0.62; p = 0.021). By histomorphometry, bone turnover was high in 50%, low in 21% and normal in 29%, while 36% showed abnormal patterns of mineralization. Significant positive associations were observed between osteoblast surface, osteoclast surface, mineralization surface and bone turnover markers.

CONCLUSIONS

Deterioration of cortical -microarchitecture despite predominantly normal trabecular parameters reinforces the importance of comprehensive cortical evaluation in patients with CKD.

Is there a practical role for bone biopsy in chronic kidney disease?

Bone biopsy is currently the only means to accurately assess renal osteodystrophy and responses to therapeutic interventions. With sedation, the technique is relatively painless, and complications are uncommon. Bone biopsy should be considered when the aetiology of symptoms or biochemical abnormalities is in question, and results may lead to changes in therapy. Although it remains prudent to use antiresorptive drugs cautiously in patients with chronic kidney disease (CKD) stages 3a-4 and low bone mineral density, bone biopsy may not be warranted before commencing therapy in these patients. Histomorphometric indices adopted for bone biopsy assessment are turnover (T), mineralisation (M) and volume (V). Often, only measurements of trabecular bone are reported; however, marked cortical changes are common in CKD and may be critical to bone structure and integrity. MicroCT of bone biopsies can rapidly assess static parameters and provides information on the cortical and trabecular compartments that may influence management. Limitations of bone biopsy include the time required for pre-biopsy tetracycline labelling and sample processing, and a paucity of facilities to process and report samples. Patients with CKD may not respond predictably to treatments, and because the biopsy sample is illustrative of activity at only one skeletal site and one point in time, assessment of real-time laboratory trends is always required. Optimally, we need a non-invasive 'virtual bone biopsy' that provides information for initiating and monitoring therapy. However, bone biopsy is the current standard by which the accuracy of investigational imaging techniques, hormonal values and biochemical turnover markers are judged.

Worsening of soft tissue dystrophic calcification in an osteoporotic patient treated with teriparatide

Teriparatide, used for treatment of osteoporosis in patients at high risk of fracture risk, sometimes results in mild and transient hypercalcemia. There have been two recent reports of worsening dystrophic calcification in patients with autoimmune disorders following teriparatide treatment. We report a patient with severe osteoporosis and without a pre-existing autoimmune disorder, who developed symptomatic worsening of dystrophic calcification 4 months after teriparatide was initiated. Symptoms resolved within 1 week of teriparatide cessation.

Progression of arterial stiffness is associated with changes in bone mineral markers in advanced CKD

Background

Arterial stiffness is an independent predictor of all-cause and cardiovascular mortality in patients with chronic kidney disease (CKD). There are limited prospective data however on progression of arterial stiffness in CKD, including evaluating associations with bone mineral markers such as fibroblast growth factor 23 (FGF23) and soluble α-klotho (sKl).

Methods

In this prospective, single-center, observational study, arterial stiffness [measured by pulse wave velocity (PWV)] and hormones influencing mineral homeostasis, including serum FGF23 and sKl, were compared between non-dialysis CKD stages 4/5 and healthy controls at baseline and 12 months (12 m). Abdominal aortic calcification (AAC) was quantitated using lateral lumbar radiography at baseline.

Results

Forty patients with CKD [mean estimated glomerular filtration rate (eGFR) 19.5 ± 6.7 mL/min/1.73m²] and 42 controls (mean eGFR 88.6 ± 12.9 mL/min/1.73m²) completed follow-up. There were no differences in age, gender and body mass index between groups. A significant increase in FGF23 [240.6 (141.9–1129.8) to 396.8 (160.3–997.7) pg/mL, p = 0.001] was observed in the CKD group but serum phosphate, corrected calcium, parathyroid hormone and sKl did not change significantly over 12 m. At baseline, CKD subjects had higher AAC prevalence [83.8% versus (vs.) 43.6%, p = 0.002] and higher aortic PWV [9.7(7.6–11.7) vs. 8.1 (7.2–9.7) m/s, p = 0.047] compared to controls. At 12 m, aortic PWV increased by 1.3 m/s (95% confidence interval, 0.56 to 2.08, p < 0.001) in the CKD cohort, with 30% of subjects showing progression from normal aortic elasticity to stiffening (PWV > 10 m/s). Serum FGF23 was associated with AAC, abnormal PWV and progression of PWV at 12 m.

Conclusions

Arterial stiffness and serum FGF23, both of which are associated with increased cardiovascular risk, increased over one year in individuals with CKD. Additionally, a significant association was found between serum FGF23 and arterial calcification and stiffness. Larger clinical studies and further experimental work are warranted to delineate the temporal relationship as well as the pathological mechanisms linking FGF23 and vascular disease.

Electronic supplementary material

The online version of this article (10.1186/s12882-017-0705-4) contains supplementary material, which is available to authorized users.

Sevelamer Versus Calcium-Based Binders for Treatment of Hyperphosphatemia in CKD: A Meta-Analysis of Randomized Controlled Trials

BACKGROUND AND OBJECTIVES

People with CKD stages 3-5 and on dialysis (5D) have dramatically increased mortality, which has been associated with hyperphosphatemia in many studies. Oral phosphate binders are commonly prescribed to lower serum phosphate. We conducted an updated meta-analysis of the noncalcium-based binder (non-CBB) sevelamer versus CBBs in CKD stages 3-5D.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Randomized, controlled trials comparing sevelamer with CBBs were identified through MEDLINE and the Cochrane Central Register of Controlled Trials. Patient-level outcomes included all-cause mortality, cardiovascular events and mortality, hospitalization, and adverse effects. Intermediate outcomes included vascular calcification and bone changes. Biochemical outcomes included serum phosphate, calcium, parathyroid hormone, lipids, and hypercalcemia. We conducted and reported this review according to Cochrane guidelines.

RESULTS

We included 25 studies to March 31, 2015 with 4770 participants (88% on hemodialysis). Patients receiving sevelamer had lower all-cause mortality (risk ratio [RR], 0.54; 95% confidence interval [95% CI], 0.32 to 0.93), no statistically significant difference in cardiovascular mortality (n=2712; RR, 0.33; 95% CI, 0.07 to 1.64), and an increase in combined gastrointestinal events of borderline statistical significance (n=384; RR, 1.42; 95% CI, 0.97 to 2.08). For biochemical outcomes, patients receiving sevelamer had lower total serum cholesterol (mean difference [MD], -20.2 mg/dl; 95% CI, -25.9 to -14.5 mg/dl), LDL-cholesterol (MD, -21.6 mg/dl; 95% CI, -27.9 to -15.4 mg/dl), and calcium (MD, -0.4 mg/dl; 95% CI, -0.6 to -0.2 mg/dl) and a reduced risk of hypercalcemia (RR, 0.30; 95% CI, 0.19 to 0.48). End of treatment intact parathyroid hormone was significantly higher for sevelamer (MD, 32.9 pg/ml; 95% CI, 0.1 to 65.7 pg/ml). Serum phosphate values showed no significant differences.

CONCLUSIONS

Patients with CKD stages 3-5D using sevelamer have lower all-cause mortality compared with those using CBBs. Because of a lack of placebo-controlled studies, questions remain regarding phosphate binder benefits for patients with CKD stages 3-5 and not on dialysis.

Opportunistic in-hospital screening for kidney disease using the Kidney Health Check

BACKGROUND

Chronic kidney disease (CKD) is a major public health issue and early detection may prevent morbidity and mortality. Screening for CKD is simply assessed using the Kidney Health Check (KHC), a compilation of blood pressure (BP), estimated glomerular filtration rate (eGFR) and urinalysis (UA). KHC screening of high risk hospital inpatients is recommended, but its implementation and cost-effectiveness is unknown.

AIMS

We aimed to determine the proportion of patients currently tested for all components of the KHC during an acute hospital admission, and to compare the estimated costs of screening and subsequent follow-up with other screening programs.

METHODS

A retrospective audit was conducted of consecutively admitted adult patients, and the frequency of BP, eGFR and UA testing recorded. Using published data, the likely costs and benefits of components of the KHC were estimated.

RESULTS

Two hundred patients (median age 75 years, range 20-98) were assessed. All had a documented BP and eGFR, and 55% had a UA, representing a complete KHC. Of the total, 141 (71%) had one or more abnormalities detected, and of 71 with an eGFR <60 mL/min per 1.73 m(2) , only 22 (31%) had a recorded diagnosis of CKD. Estimated costs of opportunistic in-hospital KHC screening are below those of current Australian screening programs.

CONCLUSIONS

Hospital in-patients frequently have a full KHC and most have abnormalities detected. Opportunistic inpatient KHC screening would have little impact on hospital costs, but may result in significant health benefits. The KHC should be included in routine discharge documentation.

A case report of disabling bone pain after long-term kidney transplantation

A 77-year-old man, who received a renal transplant 13 years before for IgA glomerulonephritis, was referred after he developed bilateral mid-tibial aching pain that did not improve with simple analgesia. He had recently been changed from low-dose cyclosporine to tacrolimus, but the pain did not improve when this was reversed. He had a history of focal prostatic adenocarcinoma, cryptococcal lung infection, osteoporosis treated with alendronate for 2 years and multiple squamous cell carcinomas, including one requiring left neck dissection and radiotherapy. Upon physical examination, he had gouty tophi and marked bilateral tibial tenderness but had no other clinical findings. Laboratory investigations included an elevated intact parathyroid hormone value of 7.9 pmol/L (1.6 to 6.9), bone specific alkaline phosphatase of 22 µg/L (3.7 to 20.9), urinary deoxypyridinoline/creatinine ratio of 7.2 nmol/mmol (2.5 to 5.4) and C-reactive protein. Chest X-ray and tibial X-rays were normal, but there was marrow oedema and a prominent periosteal reaction on magnetic resonance imaging. A radionuclide bone scan showed increased symmetrical, linear uptake in both tibiae and the left femur, and uptake was also noted in both clinically asymptomatic humeri. Tibial bone biopsy disclosed small deposits of poorly differentiated metastatic cancer and a follow-up chest CT revealed a lung lesion. It was concluded that the bone pain and periostitis was caused by primary lung cancer with metastatic disease to bone, and an associated hypertrophic osteoarthropathy.

Effects of cholecalciferol on functional, biochemical, vascular, and quality of life outcomes in hemodialysis patients

BACKGROUND AND OBJECTIVES

Observational studies suggest that calciferol supplementation may improve laboratory and patient-level outcomes of hemodialysis patients with reduced 25-hydroxyvitamin D [25(OH)D] levels. This randomized controlled trial examined effects of cholecalciferol supplementation in patients on hemodialysis.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Sixty patients with 25(OH)D levels ≤24 ng/ml (≤60 nmol/L) were randomized to receive 50,000 IU oral cholecalciferol or placebo, once weekly for 8 weeks and then monthly for 4 months. At baseline (autumn 2011) and 6 months, testing evaluated muscle strength, functional capacity, laboratory parameters, pulse wave velocity (PWV), and health-related quality of life (HRQOL) using the Kidney Disease Quality of Life-36 survey.

RESULTS

Patients were well matched by treatment allocation. Median age was 62 years (range, 20-86), 52% were women, 55% had a history of diabetes, and mean serum 25(OH)D was 17±5 ng/ml (43±13 nmol/L). Patients were assessed over 6 months by repeated-measures ANOVA. Patients allocated to cholecalciferol had significantly higher values of 25(OH)D (P<0.001), 1,25-dihydroxyvitamin D (P=0.04), and tartrate-resistant acid phosphatase-5b) (P=0.04) and a greater reduction in phosphorus values (P=0.03) than placebo-treated patients Values of serum calcium, intact parathyroid hormone, and episodes of hypercalcemia and hyperphosphatemia did not differ significantly between the groups. No significant differences were detected in muscle strength, functional capacity, PWV, or HRQOL.

CONCLUSIONS

In this randomized controlled trial, patients supplemented with cholecalciferol had higher 25(OH)D, 1,25-dihydroxyvitamin D, and tartrate-resistant acid phosphatase-5b levels, without increased calcium or phosphorus values. However, no effects were detected in muscle strength, functional capacity, PWV, or HRQOL.

Serum levels of phosphorus, parathyroid hormone, and calcium and risks of death and cardiovascular disease in individuals with chronic kidney disease: a systematic review and meta-analysis

CONTEXT

Clinical practice guidelines on the management of mineral and bone disorders due to chronic kidney disease recommend specific treatment target levels for serum phosphorus, parathyroid hormone, and calcium.

OBJECTIVE

To assess the quality of evidence for the association between levels of serum phosphorus, parathyroid hormone, and calcium and risks of death, cardiovascular mortality, and nonfatal cardiovascular events in individuals with chronic kidney disease.

DATA SOURCES

The databases of MEDLINE (1948 to December 2010) and EMBASE (1947 to December 2010) were searched without language restriction. Hand searches also were conducted of the reference lists of primary studies, review articles, and clinical guidelines along with full-text review of any citation that appeared relevant.

STUDY SELECTION

Of 8380 citations identified in the original search, 47 cohort studies (N = 327,644 patients) met the inclusion criteria.

DATA EXTRACTION

The characteristics of study design, participants, exposures, and covariates together with the outcomes of all-cause mortality, cardiovascular mortality, and nonfatal cardiovascular events at different levels of serum phosphorus, parathyroid hormone, and calcium were analyzed within studies. Data were summarized across studies (when possible) using random-effects meta-regression.

DATA SYNTHESIS

The risk of death increased 18% for every 1-mg/dL increase in serum phosphorus (relative risk [RR], 1.18 [95% confidence interval {CI}, 1.12-1.25]). There was no significant association between all-cause mortality and serum level of parathyroid hormone (RR per 100-pg/mL increase, 1.01 [95% CI, 1.00-1.02]) or serum level of calcium (RR per 1-mg/dL increase, 1.08 [95% CI, 1.00-1.16]). Data for the association between serum level of phosphorus, parathyroid hormone, and calcium and cardiovascular death were each available in only 1 adequately adjusted cohort study. Lack of adjustment for confounding variables was not a major limitation of the available studies.

CONCLUSIONS

The evidentiary basis for a strong, consistent, and independent association between serum levels of calcium and parathyroid hormone and the risk of death and cardiovascular events in chronic kidney disease is poor. There appears to be an association between higher serum levels of phosphorus and mortality in this population.

Hypercalcaemia as a prodromal feature of indolent Pneumocystis jivorecii after renal transplantation

Following renal transplantation, hypercalcaemia is frequently caused by persisting hyperparathyroidism. Unregulated extrarenal 1,25-dihydroxyvitamin D (1,25(OH)(2)D) synthesis, which is well recognized as a cause of hypercalcaemia in granulomatous diseases, may also occur after kidney transplantation. This mechanism is also likely to be responsible for hypercalcaemia reported during treatment of cytomegalovirus and associated with acute symptomatic pneumocystis jivorecii pneumonia (PCP). Hypercalcaemia as a prodromal feature of indolent PCP has not been described. We report a renal transplant recipient who developed hypercalcaemia 30 months post-transplant due to extrarenal production of 1,25(OH)(2)D. Two months later, PCP was diagnosed and hypercalcaemia resolved after initiation of treatment.

Phosphate binders for preventing and treating bone disease in chronic kidney disease patients

BACKGROUND

Phosphate binders are widely used to lower serum phosphorus levels in people with chronic kidney disease (CKD) but their impact in CKD remains controversial.

OBJECTIVES

To review the effects of various phosphate binders on biochemical and patient-level end-points in CKD stages 3 to 5D.

SEARCH STRATEGY

In March 2010 we searched MEDLINE, EMBASE, the Cochrane Renal Group's Specialised Register and CENTRAL for relevant studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) or quasi-RCTs that assessed the effects of various phosphate binders in adults with CKD.

DATA COLLECTION AND ANALYSIS

Two authors independently reviewed search results and extracted data. Results were expressed as mean differences (MD) for continuous outcomes and risk ratios (RR) for dichotomous outcomes with 95% confidence intervals (CI) using a random-effects model.

MAIN RESULTS

Sixty studies (7631 participants) were included. There was no significant reduction in all-cause mortality (10 studies, 3079 participants: RR 0.73, 95% CI 0.46 to 1.16), or serum calcium by phosphorus (Ca x P) product with sevelamer hydrochloride compared to calcium-based agents. There was a significant reduction in serum phosphorus (16 studies, 3126 participants: MD 0.23 mg/dL, 95% CI 0.04 to 0.42) and parathyroid hormone (PTH) (12 studies, 2551 participants; MD 56 pg/mL, 95% CI 26 to 84) but a significant increase in the risk of hypercalcaemia (12 studies, 1144 participants: RR 0.45, 95% CI 0.35 to 0.59) with calcium-based agents compared to sevelamer hydrochloride. There was a significant increase in the risk of adverse gastrointestinal events with sevelamer hydrochloride in comparison to calcium salts (5 studies, 498 participants: RR 1.58, 95% CI 1.11 to 2.25). Compared with calcium-based agents, lanthanum significantly reduced serum calcium (2 studies, 122 participants: MD -0.30 mg/dL, 95% CI -0.64 to -0.25) and the Ca x P product, but not serum phosphorus levels. The effects of calcium acetate on biochemical end-points were similar to those of calcium carbonate. The phosphorus lowering effects of novel agents such as ferric citrate, colestilan and niacinamide were only reported in a few studies.

AUTHORS' CONCLUSIONS

Available phosphate-binding agents have been shown to reduce phosphorus levels in comparison to placebo. However, there are insufficient data to establish the comparative superiority of novel non-calcium binding agents over calcium-containing phosphate binders for patient-level outcomes such as all-cause mortality and cardiovascular end-points in CKD.

Association between 25-hydroxyvitamin D, somatic muscle weakness and falls risk in end-stage renal failure

OBJECTIVE

Suboptimal levels of 25-hydroxyvitamin D (25OHD) are common in haemodialysis patients (Chronic Kidney disease-5D: CKD-5D) and may be associated with reduced muscle strength and increased falls risk. We tested the hypothesis that 25OHD levels may be independently associated with falls risk in CKD-5D.

BACKGROUND

Supplementation with calcium and cholecalciferol reduces hip and other nonvertebral fractures in elderly individuals, and this effect may in part be attributable to reduction in falls frequency. The relationship between 25OHD and falls risk has not been investigated in CKD-5D.

DESIGN AND PATIENTS

This is a cross-sectional study of 25 CKD-5D patients with predialysis 25OHD, 1,25-dihydroxyvitamin D (1,25(OH)(2)D) and intact parathyroid hormone (iPTH) measurement. Falls risk was assessed by quadriceps muscle strength, FallsScreen((c)) test (FST), Berg Balance Scale (BBS), timed 'up and go' (TUG) test, Modified Barthel Index (MBI) and Falls Efficacy Scale (FES).

RESULTS

Mean age was 69.8 +/- 12.1 years, and median time on dialysis was 3.1 years. Median 25OHD level was 55.3 nmol/l (range 20.8-125.8 nmol/l). Muscle strength was significantly positively correlated with 25OHD (P = 0.024) but not with 1,25(OH)(2)D (P = 0.477) or PTH (P = 0.461). Statistically significant correlation between 25OHD levels and FST (P = 0.028) plus MBI (P = 0.0046) was noted. No significant correlation was detected between falls risk and 1,25(OH)(2)D or PTH.

CONCLUSIONS

Suboptimal levels of 25OHD in CKD-5D are associated with reduced quadriceps muscle strength and increased falls risk. 25OHD may be more important than the active renal metabolite 1,25(OH)(2)D for muscle strength with implications for vitamin D choice and goals of supplementation. Further investigation is required to examine effectiveness of calciferol supplementation on the incidence of falls in CKD-5D.

Individualized therapy to prevent bone mineral density loss after kidney and kidney-pancreas transplantation

BACKGROUND AND OBJECTIVES

Most patients who undergo kidney or kidney-pancreas transplantation have renal osteodystrophy, and immediately after transplantation bone mineral density (BMD) commonly falls. Together, these abnormalities predispose to an increased fracture incidence. Bisphosphonate or calcitriol therapy can preserve BMD after transplantation, but although bisphosphonates may be more effective, they pose potential risks for adynamic bone.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A total of 153 kidney (61%) and kidney-pancreas (39%) transplant recipients were allocated to bisphosphonate (62%) or calcitriol (38%) therapy using an algorithm that incorporated BMD, prevalent vertebral fracture, biomarkers of bone turnover, and risk factor assessment. Patients received cholecalciferol and calcium as appropriate and were followed for 12 mo.

RESULTS

Patients who were treated with bisphosphonates had lower BMD at the lumbar spine and femoral neck and longer time on dialysis. Age and gender were similar between the groups. At 12 mo, bisphosphonate-treated patients had significant BMD increases at the lumber spine and femoral neck and a negative trend at the wrist. Patients who were allocated to calcitriol, who were assessed to have lower baseline fracture risk, had no significant change in BMD at any site. At 1 yr, mean levels of bone turnover marker and intact parathyroid hormone normalized in both groups. Incident fracture rates did not differ significantly.

CONCLUSIONS

With targeted treatment, BMD levels were stable or improved and bone turnover markers normalized. This algorithm provides a guide to targeting therapy after transplantation that avoids BMD loss and may reduce suppression of bone turnover.