Prevention and treatment of renal osteodystrophy in children on chronic renal failure: European guidelines

Health-related quality of life in paediatric patients on peritoneal dialysis: Data from a tertiary centre

Kidney failure has a negative impact on both children and families' quality of life (QOL). We evaluated the burden of home peritoneal dialysis (PD) using two local questionnaires and the French version of PedsQL3.0 end-stage kidney disease module and family impact module. Data are expressed as median (min-max). We reviewed the charts of 12 patients, at a median age of 8.8 (1.2-16.7) years, undergoing maintenance PD for 8 (1-42) months. Parathyroid hormone and haemoglobin levels were 215 (17-606) ng/L and 117 (104-141) g/L, respectively. Patients were taking 7 (3-10) different medications, corresponding to 9 (4-17) doses per day. The PD fluid volume per cycle was 1035 (723-1348) mL/m2 with a dwell duration of 75 (60-90) min and 6 (5-9) cycles per night. On a 2-week period, there were 2 (1-11) alarms per night resulting in 2 (0-8) times waking up and getting out of the bed for the parent(s); families were late 1 (0-11) times for school or parent's work. The time spent to connect and disconnect the cycler to the patient was 30 (12-46) min per day. QOL score on child self-report was correlated positively with weight percentile for age (R = 0.857; p = 0.014) and negatively with the number of siblings (R = -0.917; p = 0.004). The children QOL was evaluated higher by self-report scores: 77 (59-87) than by parent-proxy report scores: 53 (29-74), respectively (p = 0.028). PD children/teenagers and their caregivers can feel overwhelmed by the daily home therapy. Self-report and parent-proxy report QOL were significantly different, and it is questionable whether the parent-proxy report QOL relies rather on parents' own QOL.

Surgical treatment of secondary hyperparathyroidism in children with chronic kidney disease. Experience in 19 patients

OBJECTIVES

Secondary hyperparathyroidism (sHPT) is an important contributor to bone disease and cardiovascular calcifications in children with chronic kidney disease (CKD). When conservative measures are ineffective, parathyroidectomy is indicated. The aim of our study was to evaluate the efficacy and safety of subtotal parathyroidectomy (sPTX) in pediatric and adolescent patients, and to provide a rationale for considering this aggressive treatment in CKD patients with uncontrolled sHPT.

METHODS

We retrospectively analyzed the medical records of 19 pediatric CKD patients on dialysis with refractory sHPT who underwent sPTX at our institution between 2010 and 2020. All patients had clinical, radiological, and biochemical signs of renal osteodystrophy.

RESULTS

One year after sPTX, parathyroid hormone (PTH) levels (median and interquartile range (IQR)) dropped from 2073 (1339-2484) to 164 (93-252) pg/mL (p=0.0001), alkaline phosphatase (ALP) levels from 1166 (764-2373) to 410 (126-421) IU/L (p=0.002), and the mean (±SDS) calcium-phosphate (Ca*P) product from 51±11 to 41±13 mg2/dL2 (p=0.07). Postoperatively, all patients presented with severe hungry bone syndrome (HBS) and required intravenous and oral calcium and calcitriol supplementation. None of them had other postoperative complication. Histological findings had a good correlation with preoperative parathyroid ultrasound imaging (n: 15) in 100 % and with technetium-99m (99mTc) sestamibi scintigraphy (n: 15) in 86.6 %. Clinical and radiological signs of bone disease improved in all patients.

CONCLUSIONS

Pediatric sPTX is effective and safe to control sHPT and calcium-phosphate metabolism in children with CKD on dialysis and may mitigate irreversible bone deformities and progression of cardiovascular disease.

Impact of Cinacalcet and Etelcalcetide on Bone Mineral and Cardiovascular Disease in Dialysis Patients

PURPOSES OF REVIEW

With chronic kidney disease (CKD) progression, secondary hyperparathyroidism (sHPT) and mineral and bone metabolism disease (MBD) almost inevitably develop and result in renal osteodystrophy and cardiovascular disease (CVD). Together with active vitamin D, calcimimetics are the main therapy for sHPT in CKD. This review provides an overview of the therapeutic effects of oral cinacalcet and intravenous etelcalcetide on CKD-MBD and vascular disease, with a focus on pediatric dialysis patients.

RECENT FINDINGS

Randomized controlled trials in adults and children demonstrate efficient lowering of parathyroid hormone (PTH) by the calcimimetics together with a reduction in serum calcium and phosphate when combined with low-dose active vitamin D, while therapy with active vitamin D analogs alone increases serum calcium and phosphate. Cinacalcet and etelcalcetide both improve bone formation and correct adynamic bone, i.e., have a direct bone anabolic effect. They decrease serum calciprotein particles, which are involved in endothelial dysfunction, atherogenesis, and vascular calcification. Clinical trials in adults suggest a modest slowing of the progression of cardiovascular calcification with cinacalcet. Calcimimetic agents represent a major pharmacological tool for improved control of CKD-MBD, by efficiently counteracting sHPT and allowing for better control of calcium/phosphate and bone homeostasis. Albeit definite evidence is lacking, the beneficial effects of calcimimetics on CVD are promising. Routine use of cinacalcet has been suggested in children.

Pediatric Chronic Kidney Disease

Chronic kidney disease (CKD) in children has a significant impact on morbidity, mortality, and quality of life. The degree of renal dysfunction should be calculated using pediatric-specific formulas and the degree of CKD staged; this allows for appropriate dosing of medications based on renal function and monitoring for progression and comorbid conditions including metabolic acidosis, bone disease, anemia, cardiovascular complications, malnutrition and electrolyte abnormalities, growth failure, and psychosocial issues. Treatment strategies include treating the underlying disease and using general renal protective measures. Effective management of these complex issues requires a specialized multidisciplinary team approach.

Size-adjustment techniques of lumbar spine dual energy X-ray absorptiometry measurements in assessing bone mineralization in children on maintenance hemodialysis

OBJECTIVES

Growing skeleton is uniquely vulnerable to impaired mineralization in chronic kidney disease (CKD). Continued debate exists about the optimal method to adjust for body size when interpreting dual energy X-ray absorptiometry (DXA) scans in children with CKD given the burden of poor growth. The study aimed to evaluate the clinical usefulness of size-adjustment techniques of lumber-spine DXA measurements in assessing bone mineralization in children with kidney failure on maintenance hemodialysis (HD).

METHODS

Case-control study included 93 children on maintenance HD (9-18 years; 48 males). Participants were subjected to spinal-DXA-scan to obtain areal bone mineral density (aBMD; g/cm²). Volumetric-BMD (vBMD; g/cm³) was mathematically estimated. Z-scores of aBMD for chronological age (aBMD_Z-CA), aBMD adjusted for height age (aBMD_Z-HA), and vBMD_Z-score were calculated using mean and SD values of age subgroups of 442 healthy controls (7-18 years).

RESULTS

In short-for-age CKD patients, aBMD_Z-CA was significantly lower than vBMD_Z-score, while aBMD_Z-HA was significantly higher than aBMD_Z-CA and vBMD_Z-score. In normal height-for-age CKD patients, no significant difference between aBMD_Z-scores and vBMD_Z-score was detected. aBMD_Z-CA was significantly lower and aBMD_Z-HA was significantly higher in short-for-age compared to normal height-for-age patients without significant differences in vBMD_Z-score. We observed age-related decrements in the percentage of HD patients with normal densitometric Z-scores, the effect of age was less pronounced in aBMD_Z-HA than vBMD_Z-score. vBMD_Z-score correlated negatively with age, but not with height_Z-score.

CONCLUSIONS

Estimated vBMD seems to be a convenient size-adjustment approach of spinal-DXA measurements in assessing BMD especially in older short-for-age children with CKD. aBMD_Z-CA underestimates, while aBMD_Z-HA overestimates BMD in such patients.

Bone Disease in CKD in Children

This manuscript discusses mineral and bone disorders of chronic kidney disease (MBD-CKD) in pediatric patients with special emphasis on the underlying pathophysiology, the causes and clinical profile of growth retardation, the alterations in the growth plate, the strategies to optimize growth and the medical recommendations for prevention and treatment.

Bone evaluation in paediatric chronic kidney disease: clinical practice points from the European Society for Paediatric Nephrology CKD-MBD and Dialysis working groups and CKD-MBD working group of the ERA-EDTA

Mineral and bone disorder (MBD) is widely prevalent in children with chronic kidney disease (CKD) and is associated with significant morbidity. CKD may cause disturbances in bone remodelling/modelling, which are more pronounced in the growing skeleton, manifesting as short stature, bone pain and deformities, fractures, slipped epiphyses and ectopic calcifications. Although assessment of bone health is a key element in the clinical care of children with CKD, it remains a major challenge for physicians. On the one hand, bone biopsy with histomorphometry is the gold standard for assessing bone health, but it is expensive, invasive and requires expertise in the interpretation of bone histology. On the other hand, currently available non-invasive measures, including dual-energy X-ray absorptiometry and biomarkers of bone formation/resorption, are affected by growth and pubertal status and have limited sensitivity and specificity in predicting changes in bone turnover and mineralization. In the absence of high-quality evidence, there are wide variations in clinical practice in the diagnosis and management of CKD-MBD in childhood. We present clinical practice points (CPPs) on the assessment of bone disease in children with CKD Stages 2-5 and on dialysis based on the best available evidence and consensus of experts from the CKD-MBD and Dialysis working groups of the European Society for Paediatric Nephrology and the CKD-MBD working group of the European Renal Association-European Dialysis and Transplant Association. These CPPs should be carefully considered by treating physicians and adapted to individual patients' needs as appropriate. Further areas for research are suggested.

A retrospective study of end-stage kidney disease patients on maintenance hemodialysis with renal osteodystrophy-associated fragility fractures

BACKGROUND

Nephropathy associated metabolic disorder induces high incidence of fragility fracture in end-stage renal disease (ESRD) patients. As the risk factors and prognosis of fragility fracture in ESRD patients are unclear, more research is needed. This study aimed to evaluate various risk factors for ESRD-related fragility fractures, explore factors affecting the prognosis of patients with such fractures, and provide information for prevention and treatment of renal osteopathy to improve the prognosis of patients.

METHODS

In this retrospective case-control study, the case notes of 521 ESRD patients who received maintenance dialysis for at least 3 months were examined. Finally, 44 patients diagnosed with fragility fractures were assigned to the fragility fracture (FF) group and 192 patients were included in the control group (CG). Demographic information, underlying diseases, nutritional, bone metabolism, and renal function parameters, along with the number and causes of any deaths, were recorded for multiple statistical analysis.

RESULTS

The FF group had increased incidences of essential hypertension and diabetes mellitus and higher serum calcium, corrected calcium, alkaline phosphatase, and hemoglobin levels. Immunoreactive parathyroid hormone (iPTH), total cholesterol (TC), and low density lipoprotein (LDL) levels were higher in the CG. Multivariate Cox regression analysis revealed that fragility fracture was an independent risk factor for all-cause mortality in ESRD patients (P < .001, RR: 4.877, 95% CI: 2.367-10.013).

CONCLUSIONS

Essential hypertension and diabetes, high serum calcium and alkaline phosphatase levels, and reduced iPTH levels were risk factors for fragility fracture in ESRD patients. Maintaining iPTH and serum TC levels may protect against fragility fractures in them. Fragility fractures may yield poor prognosis and shorter lifespan. The presence of fragility fracture was an independent predictor of all-cause death in ESRD patients.

CKD-MBD post kidney transplantation

Complications of chronic kidney disease-associated mineral and bone disorders (CKD-MBD) are frequently observed in pediatric kidney transplant recipients and are associated with high morbidity, including growth failure, leg deformities, bone pain, fractures, osteonecrosis, and vascular calcification. Post-transplant CKD-MBD is mainly due to preexisting renal osteodystrophy and cardiovascular changes at the time of transplantation, glucocorticoid treatment, and reduced graft function. In addition, persistent elevated levels of parathyroid hormone (PTH) and fibroblast growth factor 23 may cause hypophosphatemia, resulting in impaired bone mineralization. Patient monitoring should include assessment of growth, leg deformities, and serum levels of calcium, phosphate, magnesium, alkaline phosphatase, 25-hydroxyvitamin D, and PTH. Therapy should primarily focus on regular physical activity, preservation of transplant function, and steroid-sparing immunosuppressive protocols. In addition, adequate monitoring and treatment of vitamin D and mineral metabolism including vitamin D supplementation, oral phosphate, and/or magnesium supplementation, in case of persistent hypophosphatemia/hypomagnesemia, and treatment with active vitamin D in cases of persistent secondary hyperparathyroidism. The latter should be done using the minimum PTH-suppressive dosages aiming at the recommended CKD stage-dependent PTH target range. Finally, treatment with recombinant human growth hormone should be considered in patients lacking catch-up growth within the first year after transplantation.

Hyperphosphatemia and Chronic Kidney Disease: A Major Daily Concern Both in Adults and in Children

Hyperphosphatemia is common in chronic kidney disease (CKD). Often seen as the "silent killer" because of its dramatic effect on vascular calcifications, hyperphosphatemia explains, at least partly, the onset of the complex mineral and bone disorders associated with CKD (CKD-MBD), together with hypocalcemia and decreased 1-25(OH)₂ vitamin D levels. The impact of CKD-MBD may be immediate with abnormalities of bone and mineral metabolism with secondary hyperparathyroidism and increased FGF23 levels, or delayed with poor growth, bone deformities, fractures, and vascular calcifications, leading to increased morbidity and mortality. The global management of CKD-MBD has been detailed in international guidelines for adults and children, however, with difficulties to obtain an agreement on the ideal PTH targets. The clinical management of hyperphosphatemia is a daily challenge for nephrologists and pediatric nephrologists, notably because of the phosphate overload in occidental diets that is mainly due to the phosphate "hidden" in food additives. The management begins with a dietary restriction of phosphate intake, and is followed by the use of calcium-based and non-calcium-based phosphate binders, and/or the intensification of dialysis. The objective of this review is to provide an overview of the pathophysiology of hyperphosphatemia in CKD, with a focus on its deleterious effects and a description of the clinical management of hyperphosphatemia in a more global setting of CKD-MBD.

Enteral Ca-Intake May Be Low and Affects Serum-PTH-Levels in Pre-school Children With Chronic Kidney Disease

Treatment of chronic kidney disease (CKD) mineral bone disorder (MBD) is challenging in growing children due to the high amount of calcium needed for normal bone mineralization and the required dietary phosphate restriction, which often includes intake of calcium-rich products such as milk. Therefore, enteral calcium-intake (Ca-I) was calculated. Patients: We looked at pediatric CKD-Patients aged 0-6 years. Design: We used a retrospective analysis of Ca-I from dietary data collections. Ca-I below 60% or above 100% of the D-A-CH and the KDOQI reference values were considered as severe Ca deficiency or Ca overload, respectively. Results: We had 41 children, median age 1.1 (range 0-5.8) years, body weight 7.3 (2.4-19.9) kg, and length 68 (48-105) cm at the time of first dietary data collection. Renal function was classified as CKD stage III in 20, IV in 28, V in 44, and VD in 142 dietary data collections. At the first dietary data collection, 5 children were in the CKD stage III, 10 in IV, 9 in V, and 17 were on dialysis. Only one child progressed to a higher CKD stage. In total, 234 dietary data collections were analyzed, and 65 follow-up collections were available from 33 children after a time interval of 26 (1-372) days. The median caloric intake was 120 (47-217)% of D-A-CH RDI. In 149 (63.6%) of the dietary data collections, enteral Ca-I was below the target (<100% of the D-A-CH and KDOQI RDI). Severe Ca-deficiency was found in 11 (26%) and 4 (12%) of the children at the first and second dietary data collection, respectively. In total, 11 children were on Ca-containing phosphate binders. In dietary data collection 1 and 2, there were seven children. From these, 4/7 and 4/7 patients had an enteral total Ca-I above the 100% D-A-CH-limit or above the KDOQI limit, respectively. Absolute dietary Ca-I and Ca-I normalized to body weight correlated negatively with PTH (r = -0.196, p < 0.005 and r = -0.13, p < 0.05). Conclusion: Enteral Ca-I should repeatedly be monitored in CKD children because many may may otherwise be underexposed to enteral calcium and overexposed when calcium-containing phosphate binders are given. Our findings suggest a major impact of dietary calcium supply on bone health in pediatric CKD.

Inhibition of Osteoclast Differentiation by 1.25-D and the Calcimimetic KP2326 Reveals 1.25-D Resistance in Advanced CKD

Active vitamin D analogs and calcimimetics are the main therapies used for treating secondary hyperparathyroidism (SHPT) in patients with chronic kidney disease (CKD). Peripheral blood mononuclear cells of 19 pediatric patients with CKD1-5D and 6 healthy donors (HD) were differentiated into mature osteoclasts with receptor activator of NF-κB ligand (RANKL) and macrophage colony-stimulating factor (M-CSF). The effects of single or combined treatment with active vitamin D (1.25-D) and/or calcimimetic KP2326 were evaluated on osteoclastic differentiation and osteoclastic-mediated bone resorption. Although 1.25-D inhibited osteoclastic differentiation, a significant resistance to 1.25-D was observed when glomerular filtration rate decreased. A significant albeit less important inhibitory effect of KP2326 on osteoclastic differentiation was also found both in cells derived from HD and CKD patients, through a putative activation of the Erk pathway. This inhibitory effect was not modified by CKD stage. Combinatorial treatment with 1.25-D and KP2326 did not result in synergistic effects. Last, KP2326 significantly inhibited osteoclast-mediated bone resorption. Both 1.25-D and KP2326 inhibit osteoclastic differentiation, however, to a different extent. There is a progressive resistance to 1.25-D in advanced CKD that is not found with KP2326. KP2326 also inhibits bone resorption. Given that 1.25-D has no effect on osteoclastic resorption activity and that calcimimetics also have direct anabolic effects on osteoblasts, there is an experimental rationale that could favor the use of decreased doses of 1.25-D with low doses of calcimimetics in SHPT in dialysis to improve the underlying osteodystrophy. However, this last point deserves confirmatory clinical studies. © 2020 American Society for Bone and Mineral Research.

Routine serum biomarkers, but not dual-energy X-ray absorptiometry, correlate with cortical bone mineral density in children and young adults with chronic kidney disease

Background. Biomarkers and dual-energy X-ray absorptiometry (DXA) are thought to be poor predictors of bone mineral density (BMD). The Kidney Disease: Improving Global Outcomes guidelines suggest using DXA if the results will affect patient management, but this has not been studied in children or young adults in whom bone mineral accretion continues to 30 years of age. We studied the clinical utility of DXA and serum biomarkers against tibial cortical BMD (CortBMD) measured by peripheral quantitative computed tomography, expressed as Z-score CortBMD, which predicts fracture risk.

Methods. This was a cross-sectional multicentre study in 26 patients with CKD4 and 5 and 77 on dialysis.

Results. Significant bone pain that hindered activities of daily living was present in 58%, and 10% had at least one low-trauma fracture. CortBMD and cortical mineral content Z-scores were lower in dialysis compared with CKD patients (P = 0.004 and P = 0.02). DXA BMD hip and lumbar spine Z-scores did not correlate with CortBMD or biomarkers. CortBMD was negatively associated with parathyroid hormone (PTH; r = −0.44, P &lt; 0.0001) and alkaline phosphatase (ALP; r = −0.22, P = 0.03) and positively with calcium (Ca; r = 0.33, P = 0.001). At PTH &lt;3 times upper limit of normal, none of the patients had a CortBMD below −2 SD (odds ratio 95% confidence interval 7.331 to infinity). On multivariable linear regression PTH (β = −0.43 , P &lt; 0.0001), ALP (β = −0.36, P &lt; 0.0001) and Ca (β = 0.21, P = 0.005) together predicted 57% of variability in CortBMD. DXA measures did not improve this model.

Conclusions. Taken together, routinely used biomarkers, PTH, ALP and Ca, but not DXA, are moderate predictors of cortical BMD. DXA is not clinically useful and should not be routinely performed in children and young adults with CKD 4–5D.

Differences in Dietary Intake and Vitamin and Mineral Status of Infants and Children on Dialysis Receiving Feeds or Eating Normal Food

OBJECTIVES

Knowledge of the vitamin and mineral intake and status of children on dialysis is scarce. Guidelines suggest supplementation of water-soluble vitamins, but the need for supplementation of minerals is less clear. We evaluated vitamin and mineral intake and status of children on chronic dialysis in our center.

METHODS

We reviewed patient records of all 33 children aged 0-16 years who were treated with chronic dialysis at a University Hospital between December 2014 and August 2019. Dietary intake was estimated from feed prescriptions and 3-day food records. Vitamin and mineral determinations were performed as part of routine care.

RESULTS

Food records or adherence to dietary prescription of feeds were available for 29 children. Dietary intake of most nutrients was sufficient in children on feeds, but children not on feeds had low intakes of vitamins D, B1, B2, and B6 as well as zinc, iron, and calcium from their diet. Insufficient intake was corrected with supplementation. We discovered some children with blood concentrations below the reference range for vitamins D (3.1%) and C (15.4%) and copper (16.7%) and selenium (3.1%). In contrast, various proportions of children with blood concentrations above the reference range were detected for all nutrients apart from vitamin D.

CONCLUSIONS

In our study, children receiving sufficient amounts of renal-specific feeds to meet at least 100% of age-specific requirements do not appear to need multivitamin-mineral supplementation, apart from vitamin D and calcium; in addition, children on PD usually need a sodium supplement and, on rare occasions with low intake from feeds, a phosphate supplement is needed. This study further revealed that other children at our center are more prone to deficient intakes of several vitamins and minerals, requiring supplementation based on dietetic review and, in some instances, laboratory measurements.

Cinacalcet studies in pediatric subjects with secondary hyperparathyroidism receiving dialysis

BACKGROUND

Secondary hyperparathyroidism (sHPT), a complication of chronic kidney disease (CKD) characterized by persistently elevated parathyroid hormone (PTH), alterations in calcium-phosphorus homeostasis, and vitamin D metabolism, affects 50% of children receiving dialysis. A significant proportion of these children develop CKD-mineral and bone disorder (CKD-MBD), associated with an increased risk of fractures and vascular calcification. The standard of care for sHPT in children includes vitamin D sterols, calcium supplementation, and phosphate binders. Several agents are approved for sHPT treatment in adults undergoing dialysis, including vitamin D analogs and calcimimetics, with limited information on their safety and efficacy in children. The calcimimetic cinacalcet is approved for use in adults with sHPT on dialysis, but is not approved for pediatric use outside Europe.

METHODS

This review provides dosing, safety, and efficacy information from Amgen-sponsored cinacalcet pediatric trials and data from non-Amgen sponsored clinical studies.

RESULTS

The Amgen cinacalcet pediatric clinical development program consisted of two Phase 3 randomized studies, one Phase 3 single arm extension study, one open-label Phase 2 study, and two open-label Phase 1 studies. Effects of cinacalcet on PTH varied across studies. Overall, 7.4 to 57.1% of subjects who received cinacalcet in an Amgen clinical trial attained PTH levels within recommended target ranges and 22.2 to 70.6% observed a ≥ 30% reduction in PTH. In addition, significant reductions in PTH were demonstrated in all non-Amgen-supported studies.

CONCLUSIONS

To help inform the pediatric nephrology community, this manuscript contains the most comprehensive review of cinacalcet usage in pediatric CKD patients to date.

Cinacalcet use in paediatric dialysis: a position statement from the European Society for Paediatric Nephrology and the Chronic Kidney Disease-Mineral and Bone Disorders Working Group of the ERA-EDTA

Secondary hyperparathyroidism (SHPT) is an important complication of advanced chronic kidney disease (CKD) in children, which is often difficult to treat with conventional therapy. The calcimimetic cinacalcet is an allosteric modulator of the calcium-sensing receptor. It has proven to be effective and safe in adults to suppress parathyroid hormone (PTH), but data on its use in children are limited. To date, studies in children only consist of two randomized controlled trials, nine uncontrolled interventional or observational studies, and case reports that report the efficacy of cinacalcet as a PTH-lowering compound. In 2017, the European Medical Agency approved the use of cinacalcet for the treatment of SHPT in children on dialysis in whom SHPT is not adequately controlled with standard therapy. Since evidence-based guidelines are so far lacking, we present a position statement on the use of cinacalcet in paediatric dialysis patients based on the available evidence and opinion of experts from the European Society for Paediatric Nephrology, Chronic Kidney Disease-Mineral and Bone Disorder and Dialysis Working Groups, and the ERA-EDTA. Given the limited available evidence the strength of these statements are weak to moderate, and must be carefully considered by the treating physician and adapted to individual patient needs as appropriate. Audit and research recommendations to study key outcome measures in paediatric dialysis patients receiving cinacalcet are suggested.

Treatment of hyperphosphatemia: the dangers of high PTH levels

The control of secondary hyperparathyroidism (SHPT) in pediatric chronic kidney disease is of utmost importance. Even though parathyroid hormone (PTH) is an important biomarker of mineral and bone disorders associated to CKD (CKD-MBD), calcium, phosphate, alkaline phosphatase, and vitamin D are also crucial and should be assessed together. In pediatric dialysis, high PTH levels have been associated with impaired longitudinal growth, bone disease, cardiovascular comorbidities, left ventricular hypertrophy, anemia, and even mortality (when PTH levels were above 500 pg/mL, i.e., 8.3-fold the upper normal limit (UNL)). As such, high PTH levels are for sure deleterious, but too low PTH levels have also been shown to impair growth and to promote vascular calcifications because of the underlying adynamic bone. This manuscript is part of a pros and cons debate for keeping PTH levels within the normal range in pediatric CKD, focusing on the pros. High bone turnover lesions can occur at lower PTH levels than "current" guidelines would suggest; thus, PTH alone is not a good predictor of the underlying osteodystrophy. PTH results can vary locally depending on the assay. Existing guidelines for PTH targets are conflicting and based on a very little evidence. However, the 120-180 pg/mL (2- to 3-fold the UNL) range is common to most of the guidelines; it seems to be a reasonable target in children undergoing dialysis, even though it does not correspond to "normal" PTH levels. As always, the philosophy of PTH levels in pediatric dialysis may be balanced, i.e., "not too low, not too high, and keep phosphate under control."

Treatment of hyperphosphatemia: the dangers of aiming for normal PTH levels

Secondary hyperparathyroidism is part of the complex of chronic kidney disease-associated mineral and bone disorders (CKD-MBD) and is linked with high bone turnover, ectopic calcification, and increased cardiovascular mortality. Therefore, measures for CKD-MBD aim at lowering PTH levels, but there is no general consensus on optimal PTH target values. This manuscript is part of a pros and cons debate for keeping PTH levels within the normal range in children with CKD, focusing on the cons. We conclude that a modest increase in PTH most likely represents an appropriate adaptive response to declining kidney function in patients with CKD stages 2-5D, due to phosphaturic effects and increasing bone resistance. There is no evidence for strictly keeping PTH levels within the normal range in CKD patients with respect to bone health and cardiovascular outcome. In addition, the potentially adverse effects of PTH-lowering measures, such as active vitamin D and calcimimetics, must be taken into account. We suggest that PTH values of 1-2 times the upper normal limit (ULN) may be acceptable in children with CKD stage 2-3, and that PTH levels of 1.7-5 times UNL may be optimal in patients with CKD stage 4-5D. However, standard care of CKD-MBD in children relies on a combination of different measures in which the observation of PTH levels is only a small part of, and trends in PTH levels rather than absolute target values should determine treatment decisions in patients with CKD as recommended by the 2017 KDIGO guidelines.

Association between timing of dialysis initiation and clinical outcomes in the paediatric population: an ESPN/ERA-EDTA registry study

BACKGROUND

There is no consensus regarding the timing of dialysis therapy initiation for end-stage kidney disease (ESKD) in children. As studies investigating the association between timing of dialysis initiation and clinical outcomes are lacking, we aimed to study this relationship in a cohort of European children who started maintenance dialysis treatment.

METHODS

We used data on 2963 children from 21 different countries included in the European Society of Pediatric Nephrology/European Renal Association-European Dialysis and Transplant Association Registry who started renal replacement therapy before 18 years of age between 2000 and 2014. We compared two groups according to the estimated glomerular filtration rate (eGFR) at start: eGFR ≥8 mL/min/1.73 m2 (early starters) and eGFR <8 mL/min/1.73 m2 (late starters). The primary outcomes were patient survival and access to transplantation. Secondary outcomes were growth and cardiovascular risk factors. Sensitivity analyses were performed to account for selection- and lead time-bias.

RESULTS

The median eGFR at the start of dialysis was 6.1 for late versus 10.5 mL/min/1.73 m2 for early starters. Early starters were older [median: 11.0, interquartile range (IQR): 5.7-14.5 versus 9.4, IQR: 2.6-14.1 years]. There were no differences observed between the two groups in mortality and access to transplantation at 1, 2 and 5 years of follow-up. One-year evolution of height standard deviation scores was similar among the groups, whereas hypertension was more prevalent among late initiators. Sensitivity analyses resulted in similar findings.

CONCLUSIONS

We found no evidence for a clinically relevant benefit of early start of dialysis in children with ESKD. Presence of cardiovascular risk factors, such as high blood pressure, should be taken into account when deciding to initiate or postpone dialysis in children with ESKD, as this affects the survival.

Vigier R, Zustin J, Haffner D. Management of bone disease in cystinosis: Statement from an international conference

Cystinosis is an autosomal recessive storage disease due to impaired transport of cystine out of lysosomes. Since the accumulation of intracellular cystine affects all organs and tissues, the management of cystinosis requires a specialized multidisciplinary team consisting of pediatricians, nephrologists, nutritionists, ophthalmologists, endocrinologists, neurologists' geneticists, and orthopedic surgeons. Treatment with cysteamine can delay or prevent most clinical manifestations of cystinosis, except the renal Fanconi syndrome. Virtually all individuals with classical, nephropathic cystinosis suffer from cystinosis metabolic bone disease (CMBD), related to the renal Fanconi syndrome in infancy and progressive chronic kidney disease (CKD) later in life. Manifestations of CMBD include hypophosphatemic rickets in infancy, and renal osteodystrophy associated with CKD resulting in bone deformities, osteomalacia, osteoporosis, fractures, and short stature. Assessment of CMBD involves monitoring growth, leg deformities, blood levels of phosphate, electrolytes, bicarbonate, calcium, and alkaline phosphatase, periodically obtaining bone radiographs, determining levels of critical hormones and vitamins, such as thyroid hormone, parathyroid hormone, 25(OH) vitamin D, and testosterone in males, and surveillance for nonrenal complications of cystinosis such as myopathy. Treatment includes replacement of urinary losses, cystine depletion with oral cysteamine, vitamin D, hormone replacement, physical therapy, and corrective orthopedic surgery. The recommendations in this article came from an expert meeting on CMBD that took place in Salzburg, Austria, in December 2016.

Clinical practice recommendations for growth hormone treatment in children with chronic kidney disease

Achieving normal growth is one of the most challenging problems in the management of children with chronic kidney disease (CKD). Treatment with recombinant human growth hormone (GH) promotes longitudinal growth and likely enables children with CKD and short stature to reach normal adult height. Here, members of the European Society for Paediatric Nephrology (ESPN) CKD–Mineral and Bone Disorder (MBD), Dialysis and Transplantation working groups present clinical practice recommendations for the use of GH in children with CKD on dialysis and after renal transplantation. These recommendations have been developed with input from an external advisory group of paediatric endocrinologists, paediatric nephrologists and patient representatives. We recommend that children with stage 3–5 CKD or on dialysis should be candidates for GH therapy if they have persistent growth failure, defined as a height below the third percentile for age and sex and a height velocity below the twenty-fifth percentile, once other potentially treatable risk factors for growth failure have been adequately addressed and provided the child has growth potential. In children who have received a kidney transplant and fulfil the above growth criteria, we recommend initiation of GH therapy 1 year after transplantation if spontaneous catch-up growth does not occur and steroid-free immunosuppression is not a feasible option. GH should be given at dosages of 0.045–0.05 mg/kg per day by daily subcutaneous injections until the patient has reached their final height or until renal transplantation. In addition to providing treatment recommendations, a cost-effectiveness analysis is provided that might help guide decision-making.

This Evidence-Based Guideline developed by members of the European Society for Paediatric Nephrology CKD-MBD, Dialysis and Transplantation working groups presents clinical practice recommendations for the use of growth hormone in children with chronic kidney disease on dialysis and after renal transplantation.

Factors and Outcome of Renal Osteodystrophy-Associated Initial Fragility Fracture in End-Stage Renal Disease Patients

Background

Renal osteodystrophy has caused increased risk of fragility fracture in end-stage renal disease (ESRD) patients. However, risk factors and outcome of ESRD patients with fragility fracture remain uncharacterized. We aimed to assess these parameters in ESRD patients.

Summary

This retrospective case-control study analyzed 354 ESRD patients (initial fragility fracture [FF] group, n = 59; control group, n = 295). Pre-dialysis blood hemoglobin, serum albumin, lipid, calcium, phosphorus, alkaline phosphatase (ALP), and intact parathyroid hormone (iPTH) were collected. All procedures performed involving human participants were in accordance with the ethical standards of the institutional committee of The First Affiliated Hospital of Chongqing Medical University (IRB approval number 216-82), and informed consent was obtained from all participants. There were higher prevalence rates of primary hypertension and diabetes, higher serum ALP, corrected calcium, and lower serum total cholesterol, low-density lipoprotein, lipoprotein-α, and iPTH in the FF group. Fractures were more likely to occur in the higher level of corrected calcium as well as in the lower iPTH group. High corrected calcium (p = 0.010, OR = 11.308, 95% CI: 1.770-72.242) and serum ALP (p = 0.000, OR = 1.007, 95% CI: 1.004-1.011) were independent risk factors of fragility fracture. The incidence of all-cause mortality and cardiovascular (CV) events in ESRD patients with fragility fracture was higher than in those without fracture.

Key Messages

Patients with hypertension, diabetes, excessive suppression of PTH, and poor nutritional status are more prone to fractures. Serum corrected calcium and ALP were independent risk factors of fragility fracture. Patients with initial fragility fracture had more CV events and higher mortality.

Twenty years of growth hormone treatment in dialyzed children in Poland-Results of national multicenter study

PURPOSE

The aim of the study was to analyze the effect of recombinant human growth hormone (rhGH) therapy and to establish factors influencing growth rate in dialyzed children in Poland.

METHODS

We retrospectively analyzed medical records of 81 children with end-stage renal disease (ESRD) on chronic dialysis treated with rhGH for ≥12 months between 1994 and 2014. The following data were recorded: cause of ESRD, dialysis modality, age at the dialysis and rhGH initiation [years]. In addition, growth [cm], [standard deviation score - SDS], body mass index [SDS], skeletal age [years], bone mineral density [SDS], hemoglobin, total protein, albumin, urea, creatinine, calcium, phosphorus, calcium phosphorus product, PTH, and alkaline phosphatase were measured at the baseline and after 12 months.

RESULTS

Growth velocity in 81 children during one-year rhGH treatment was 7.33 ± 2.63 cm (ΔSDS 0.36 ± 0.43). Height SDS increased significantly (-3.31 ± 1.12 vs. -2.94 ± 1.15, p < 0.001). Children on peritoneal dialysis (PD) (n = 51) were younger than children on hemodialysis (HD) (n = 30) (9.92 ± 3.72 vs. 12.32 ± 3.11 years, p = 0.003). ΔSDS did not differ between PD and HD children (0.40 ± 0.33 vs. 0.30 ± 0.47, p = 0.311). Growth velocity (ΔSDS) correlated with age at dialysis initiation (r=-0.30, p = 0.009), age at rhGH treatment initiation (r=-0.35, p = 0.002), skeletal age (r=-0.36, p = 0.002), BMI SDS (r=-0.27, p = 0.019), and PTH (r=-0.27, p = 0.017). No correlation between growth velocity and other parameters was observed.

CONCLUSIONS

Treatment with rhGH in children with ESRD is effective and safe irrespective of dialysis modality. Early initiation of rhGH therapy is a crucial factor determining response to the treatment in children with ESRD.

RANKL/OPG system regulation by endogenous PTH and PTH1R/ATF4 axis in bone: Implications for bone accrual and strength in growing rats with mild uremia

Osteoprotegerin (OPG), receptor activator of NF-κB ligand (RANKL), and parathyroid hormone (PTH) play a central role in the regulation of bone turnover in chronic kidney disease (CKD), but their influence on bone mineral density (BMD) and strength remains unclear, particularly in children. We studied the clinical significance of OPG and RANKL in relation to PTH, femur weight, BMD, and bone biomechanical properties in growing rats after one month (CKD-1) and three months (CKD-3) of surgically-induced mild CKD. Gene expression of parathyroid hormone 1 receptor (PTH1R) and activating transcription factor 4 (ATF4), major regulators of anabolic PTH response in bone, was also determined. Serum PTH and bone PTH1R/ATF4 expression was elevated in CKD-3 compared with other groups, and it positively correlated with femur weight, BMD, and the biomechanical properties of the femoral diaphysis reflecting cortical bone strength. In contrast, bone RANKL/OPG ratios were decreased in CKD-3 rats compared with other groups, and they were inversely correlated with PTH and the other abovementioned bone parameters. However, the PTH-PTH1R-ATF4 axis exerted an unfavorable effect on the biomechanical properties of the femoral neck. In conclusion, this study showed for the first time an inverse association between serum PTH and the bone RANKL/OPG system in growing rats with mild CKD. A decrease in the RANKL/OPG ratio, associated with PTH-dependent activation of the anabolic PTH1R/ATF4 pathway, seems to be responsible for the unexpected, beneficial effect of PTH on cortical bone accrual and strength. Simultaneously, impaired biomechanical properties of the femoral neck were observed, making this bone site more susceptible to fractures.

Efficacy and safety of sevelamer carbonate in hyperphosphatemic pediatric patients with chronic kidney disease

BACKGROUND

Treatment for hyperphosphatemia in chronic kidney disease (CKD) involves dietary control of phosphorus intake, dialysis, and treatment with oral phosphate binders, none of which were approved by the Federal Food and Drug Administration in pediatric patients at the time of this study.

METHODS

This was a phase 2, multicenter study (NCT01574326) with a 2-week, randomized, placebo-controlled, fixed-dose period (FDP) followed by a 6-month, single-arm, open-label, dose-titration period (DTP), with the aim to evaluate the safety and efficacy of sevelamer carbonate (SC) in hyperphosphatemic pediatric patients with CKD. Following a 2-4 week screening phase, pediatric patients with a serum phosphorus level higher than age-appropriate levels were randomized to receive either SC or placebo as powder/tablets in 0.4-1.6 g doses, based on body surface area. The primary efficacy outcome was the change in serum phosphorus from baseline to end of the FDP in the SC versus placebo arms (analysis of covariance). The secondary outcome was mean change in serum phosphorus from baseline to end of DTP by treatment group and overall. Treatment-emergent/serious adverse events (AEs) were recorded.

RESULTS

Of 101 enrolled patients (29 centers), 66 completed the study. The majority of patients were adolescents (74%; mean age 14.1 years) and on dialysis (77%). Renal transplant was the main reason for discontinuation. SC significantly reduced serum phosphorus from baseline levels (7.16 mg/dL) during the FDP compared to placebo (least square mean difference - 0.90 mg/dL, p = 0.001) and during the DTP (- 1.18 mg/dL, p < 0.0001). The safety and tolerability of SC and placebo were similar during the FDP, with patients in both groups reporting mild/moderate gastrointestinal AEs during the DTP.

CONCLUSIONS

Sevelamer carbonate significantly lowered serum phosphorus levels in hyperphosphatemic children with CKD, with no serious safety concerns identified.

Variability in measures of mineral metabolism in children on hemodialysis: impact on clinical decision-making

BACKGROUND

Variability in measures of mineral metabolism has not been studied in pediatric end stage kidney disease. We sought to determine the intra-individual variability in measures of mineral metabolism in children on hemodialysis (HD) and its impact on clinical decision-making.

METHODS

We conducted a prospective single-center study of children (3.6-17.3 years old) on chronic HD. Serial twice weekly measures of serum calcium, phosphate and intact parathyroid hormone (PTH), as well as weekly measures of fibroblast growth factor 23 (FGF23) and vitamin D metabolites, were obtained over a 12-week period in 10 children. Samples (n = 226) were assayed in a single batch at the end of the study.

RESULTS

The median intra-individual coefficient of variation (CV) calculated by 4-week blocks was 5.1-6.5% for calcium, 9.5-14.9% for phosphate and 32.7-33.4% for PTH. The median overall CV for FGF23 was 44.4%. Using the first value of each block as a reference, subsequent values would dictate a discrepant management decision 33-56%, 19-28%, and 30-33% of the time for calcium, phosphate, and PTH, respectively. Adjusting for sex and age, most of the variability in phosphate and PTH was attributable to within-participant variability. For calcium, 49% of the variability was attributable to day of blood collection (Monday vs. Friday). The median (range) of an individual participant's values within clinical target ranges was 55% (26-86%) for calcium, 58% (0-96%) for phosphate, and 21% (0-64%) for PTH.

CONCLUSIONS

There is considerable intra-individual variability in measures of mineral metabolism that serve as surrogate markers for bone health in children on HD. Within a 4-week period, at least 20-30% of measures would dictate a discrepant decision from the referent measure of that month. These findings have important implications for clinical decision-making and underscore the need to base therapeutic decisions on trends rather than single measurements.

Racial variation in cardiovascular disease risk factors among European children on renal replacement therapy-results from the European Society for Paediatric Nephrology/European Renal Association - European Dialysis and Transplant Association Registry

Background

Racial differences in overall mortality rates have been found in children on renal replacement therapy (RRT). We used data from the European Society for Paediatric Nephrology/European Renal Association - European Dialysis and Transplant Association Registry to study racial variation in the prevalence of cardiovascular disease (CVD) risk factors among European children on RRT.

Methods

We included patients aged <20 years between 2006-13 who (i) initiated dialysis treatment or (ii) had a renal transplant vintage of ≥1 year. Racial groups were defined as white, black, Asian and other. The CVD risk factors assessed included uncontrolled hypertension, obesity, hyperphosphataemia and anaemia. Differences between racial groups in CVD risk factors were examined using generalized estimating equation (GEE) models while adjusting for potential confounders.

Results

In this study, 1161 patients on dialysis and 1663 patients with a transplant were included. The majority of patients in both groups were white (73.8% and 79.9%, respectively). The crude prevalence of the CVD risk factors was similar across racial groups. However, after adjustment for potential confounders, Asian background was associated with higher risk of uncontrolled hypertension both in the dialysis group [odds ratio (OR): 1.27; 95% confidence interval (CI): 1.01-1.64] and the transplant group (OR: 1.37; 95% CI: 1.11-1.68) compared with white patients. Patients of Asian and other racial background with a renal transplant had a higher risk of anaemia compared with white patients (OR: 1.50; 95% CI: 1.15-1.96 and OR: 1.45; 95% CI: 1.01-2.07, respectively). Finally, the mean number of CVD risk factors among dialysis patients was higher in Asian patients (1.83, 95% CI: 1.64-2.04) compared with white patients (1.52, 95% CI: 1.40-1.65).

Conclusions

We found a higher prevalence of modifiable CVD risk factors in Asian children on RRT. Early identification and management of these risk factors could potentially improve long-term outcomes.

Care of the Pediatric Patient on Chronic Dialysis

Optimal care of the pediatric end-stage renal disease (ESRD) patient on chronic dialysis is complex and requires multidisciplinary care as well as patient/caregiver involvement. The dialysis team, along with the family and patient, should all play a role in choosing the dialysis modality which best meets the patient's needs, taking into account special considerations and management issues that may be particularly pertinent to children who receive peritoneal dialysis or hemodialysis. Meticulous attention to dialysis adequacy in terms of solute and fluid removal, as well as to a variety of clinical manifestations of ESRD, including anemia, growth and nutrition, chronic kidney disease-mineral bone disorder, cardiovascular health, and neurocognitive development, is essential. This review highlights current recommendations and advances in the care of children on dialysis with a particular focus on preventive measures to minimize ESRD-associated morbidity and mortality. Advances in dialysis care and prevention of complications related to ESRD and dialysis have led to better survival for pediatric patients on dialysis.

Effect of the timing of dialysis initiation on left ventricular hypertrophy and ınflammation in pediatric patients

BACKGROUND

The optimal time for dialysis initiation in adults and children with chronic kidney disease remains unclear. The aim of this study was to evaluate the impact of dialysis timing on different outcome parameters, in particular left ventricular (LV) morphology and inflammation, in pediatric patients receiving peritoneal dialysis and hemodialysis.

METHODS

The medical records of pediatric dialysis patients who were followed-up in nine pediatric nephrology centers in Turkey between 2008 and 2013 were retrospectively reviewed. In addition to demographic data, we retrieved anthropometric measurements, data on dialysis treatment modalities, routine biochemical parameters, complete blood count, serum ferritin, parathormone, C-reactive protein (CRP), and albumin levels, as well as echocardiographic data and hospitalization records. The patients were divided into two groups based on their estimated glomerular filtration rate (eGFR) levels at dialysis initiation, namely, an early-start group, characterized by an eGFR of >10 ml/min/1.73 m², and a late-start group, with an eGFR of < 7 ml/min/1.73 m². The collected data were compared between these groups.

RESULTS

A total of 245 pediatric dialysis patients (mean age ± standard deviation 12.3 ± 5.1 years, range 0.5-21 years) were enrolled in this study. Echocardiographic data were available for 137 patients, and the mean LV mass index (LVMI) was 58 ± 31 (range 21-215) g/m^2.7. The LVMI was 75 ± 30 g/m^2.7(n = 81) and 34 ± 6 g/m^2.7(n = 56) in patients with or without LV hypertrophy (LVH) (p < 0.001). Early-start (eGFR >10 ml/min/1.73 m²) versus late-start dialysis (eGFR < 7 ml/min/1.73 m²) groups did not significantly differ in LVMI and LVH status (p > 0.05) nor in number of hospitalizations. Serum albumin levels were significantly higher in the early-dialysis group compared with the late-dialysis group (3.3 ± 0.7 vs. 3.1 ± 0.7 g/dl, respectively; p < 0.05). The early-start group had relatively higher time-averaged albumin levels (3.2 ± 0.5 vs. 3.1 ± 0.5 g/dl; p = > 0.05) and relatively lower CRP levels (3.64 ± 2.00 vs. 4.37 ± 3.28 mg/L, p > 0.05) than the late-start group, but these differences did not reach statistical significance.

CONCLUSION

Although early dialysis initiation did not have a significant effect on important clinical outcome parameters, including LVH, inflammatory state, and hospitalization, in our pediatric dialysis patients, this area of study deserves further attention.

Clinical practice recommendations for treatment with active vitamin D analogues in children with chronic kidney disease Stages 2-5 and on dialysis

In patients with chronic kidney disease (CKD), renal synthesis of active vitamin D [1,25-dihydroxyvitamin D (1,25(OH)2D)] declines and is associated with hypocalcaemia, secondary hyperparathyroidism and the spectrum of CKD-mineral and bone disorder (MBD). In advanced CKD, active vitamin D analogues, including alfacalcidol, calcitriol and paricalcitol, are routinely administered. There are few studies on the use of vitamin D analogues in children with CKD and on dialysis. It is difficult to define bone-specific outcomes that can guide treatment with active vitamin D analogues in children with CKD-MBD. A core working group (WG) of the European Society for Paediatric Nephrology (ESPN) CKD-MBD and Dialysis WGs has developed recommendations for the use of active vitamin D therapy in children with CKD and on dialysis. A second document in parallel with this one covers treatment recommendations for native vitamin D therapy. The WGs have performed an extensive literature review to include systematic reviews and randomized controlled trials in adults and children with CKD and prospective observational studies in children with CKD. The Grading of Recommendation, Assessment, Development and Evaluation (GRADE) system was used to develop and grade the recommendations. In the absence of applicable study data, the opinion of experts from the ESPN CKD-MBD and Dialysis WGs is provided, but clearly GRADE-ed as such and must be carefully considered by the treating physician and adapted to individual patient needs as appropriate.

Oral paricalcitol: expanding therapeutic options for pediatric chronic kidney disease patients

The complex pathophysiology of progressive chronic kidney disease (CKD) and the development of mineral and bone disorder, abbreviated as CKD-MBD, is of vital importance to a pediatric patient. Paricalcitol, the 19 nor-1,25(OH)₂D₂ analogue was shown to be effective and safe in the treatment of secondary hyperparathyroidism (SHPT) in adults almost two decades ago. It also significantly improved survival in dialysis patients compared to the standard calcitriol. The successful treatment of CKD-MBD in children is essential if they are to grow and survive into adulthood. It can be argued that it is more important for children with CKD than adults since they have early and prolonged disease risk exposure. In this issue of Pediatric Nephrology, Webb et.al. report a dual trial of the safety, efficacy, and pharmacokinetics of paricalcitol in children aged 10-16 years with moderate but significant efficacy in meeting the endpoint of >30% decrease in parathyroid hormone (PTH) levels from baseline with minimal adverse events. Much more research needs to be done to expand and develop clinical pharmaceutical trials in the use of paricalcitol in children, especially in the younger age categories. This current study has done much to open the doors for future studies, with the caveat that it has been long coming and much more needs to be done to compensate for this delay in the treatment of children with CKD-MBD and cardiovascular and renal disease progression.

[Diagnosis and management of chronic kidney disease in children: Guidelines of the French Society of Pediatric Nephrology]

These guidelines are intended to assist physicians in the care of children with chronic kidney disease (CKD), defined in children as in adults, regardless of its cause. Often silent for a long time, CKD can evolve to chronic renal failure or end-stage renal disease. Its management aims at slowing disease progression and treating CKD complications as soon as they appear. The different aspects of pediatric CKD care are addressed in these guidelines (screening, treatment, monitoring, diet, quality of life) as proposed by the French Society of Pediatric Nephrology. Highly specialized care provided in the hospital setting by pediatric nephrologists is not detailed.

Chronic kidney disease in children

Chronic kidney disease (CKD) is a major health problem worldwide. Although relatively uncommon in children, it can be a devastating illness with many long-term consequences. CKD presents unique features in childhood and may be considered, at least in part, as a stand-alone nosologic entity. Moreover, some typical features of paediatric CKD, such as the disease aetiology or cardiovascular complications, will not only influence the child's health, but also have long-term impact on the life of the adult that they will become. In this review we will focus on the unique issues of paediatric CKD, in terms of aetiology, clinical features and treatment. In addition, we will discuss factors related to CKD that start during childhood and require appropriate treatments in order to optimize health outcomes and transition to nephrologist management in adult life.

Prevalence of Hyperparathyroidism, Mineral and Bone Disorders in Children with Advanced Chronic Kidney Disease

OBJECTIVE

To identify the prevalence and risk factors for secondary hyperparathyroidism in children with advanced stages of chronic kidney disease (CKD).

METHODS

A retrospective cross-sectional observational study of clinical and laboratory data of pediatric patients with CKD stage 3, 4 was conducted from 2005 through 2013 at a single center in the Kingdom of Saudi Arabia.

RESULTS

One hundred nineteen children (60.5 % boys) with mean age of 10.1 ± 5.1 y were included in the study. The mean eGFR (estimated Glomerular Filtration Rate) was 18.3 ± 15.4 ml/min/1.73m(2) and the mean intact parathyroid hormone (iPTH) level was 62.2 ± 89.4 pmol/L. Patients with a high iPTH had lower eGFR than those who were euparathyroid (16 ± 13.4 vs. 29.7 ± 19 ml/min/1.73m(2), respectively; p = 0.006), had lower calcium levels (2.2 ± 0.3 vs. 2.4 ± 0.3 mmol/L; p = 0.03) and a lower bicarbonate level (21.2 ± 4.2 vs. 23.3 ± 3.2 mmol/L; p = 0.04). Three children with hyperparthyrodism (4.9 %) had fractures, 16 (26.2 %) had bone deformities compared to 5 in the euoparathyroid group (p = 0.012). Parathyroid hormone negatively correlated with the patient's eGFR (r = -0.55), serum calcium (r = -0.43), and positively correlated with serum phosphate (r = 0.38).

CONCLUSIONS

The single most important predictor of hyperparathyroidism in children in the present sample was eGFR.

Interventions for metabolic bone disease in children with chronic kidney disease

BACKGROUND

Bone disease is common in children with chronic kidney disease (CKD) and when untreated may result in bone deformities, bone pain, fractures and reduced growth rates. This is an update of a review first published in 2010.

OBJECTIVES

This review aimed to examine the benefits (improved growth rates, reduced risk of bone fractures and deformities, reduction in PTH levels) and harms (hypercalcaemia, blood vessel calcification, deterioration in kidney function) of interventions (including vitamin D preparations and phosphate binders) for the prevention and treatment of metabolic bone disease in children with CKD.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Specialised Register to 8 September 2015 through contact with the Trial's Search Co-ordinator using search terms relevant for this review.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing different interventions used to prevent or treat bone disease in children with CKD stages 2 to 5D.

DATA COLLECTION AND ANALYSIS

Data were assessed for study eligibility, risk of bias and extracted independently by two authors. Results were reported as risk ratios (RR) or risk differences (RD) with 95% confidence intervals (CI) for dichotomous outcomes. For continuous outcomes the mean difference (MD) or standardised mean difference (SMD) with 95% confidence intervals (CI) was used. Statistical analyses were performed using the random-effects model.

MAIN RESULTS

This review included 18 studies (576 children); three new studies were added for this update. Adequate sequence generation and allocation concealment were reported in 12 and 11 studies respectively. Only four studies reported blinding of children, investigators or outcome assessors. Nine studies were at low risk of attrition bias and 12 studies were at low risk of selective reporting bias.Eight different interventions were compared. Two studies compared intraperitoneal (IP) with oral calcitriol. PTH levels were significantly lower with IP compared with oral calcitriol (1 study: MD -501.00 pg/mL, 95% CI -721.54 to -280.46) but the number of children with abnormal bone histology did not differ between treatments. Three studies compared intermittent with daily oral calcitriol. The change in mean height SDS (1 study: MD 0.13, 95% CI -0.22 to 0.48) and the percentage fall in parathyroid hormone (PTH) levels at eight weeks (1 study: MD -5.50%, 95% CI -32.37 to 21.37) and 12 months (1 study: MD -6.00% 95% CI -25.27 to 13.27) did not differ between treatments.Four studies compared active vitamin D preparations (calcitriol, paricalcitol, 1α-hydroxyvitamin D) with placebo or no specific treatment. One study reported vitamin D preparations significantly reduced PTH levels (-55.00 pmol/L, 95% CI -83.03 to -26.97). There was no significant difference in hypercalcaemia risk with vitamin D preparations compared with placebo or no specific treatment (4 studies, 103 children: RD 0.08 mg/dL, 95% CI -0.08 to 0.24). However, there was heterogeneity (I(2) = 55%) with one study showing a significantly greater risk of hypercalcaemia with intravenous (IV) calcitriol administration. Two studies (97 children) compared calcitriol with other vitamin D preparations and both found no significant differences in growth between preparations.Two studies compared ergocalciferol in patients with CKD and vitamin D deficiency. Elevated PTH levels developed significantly later in ergocalciferol treated children (1 study: hazard ratio 0.30, 95% CI 0.09 to 0.93) though the number with elevated PTH levels did not differ between groups (1 study, 40 children: RR 0.33, 95% CI 0.11 to 1.05).Two studies compared calcium carbonate with aluminium hydroxide as phosphate binders. One study (17 children: MD -0.86 SDS, 95% CI -2.24 to 0.52) reported no significant difference in mean final height SDS between treatments. Three studies compared sevelamer with calcium-containing phosphate binders. There were no significant differences in the final calcium, phosphorus or PTH levels between binders. More episodes of hypercalcaemia occurred with calcium-containing binders. One study reported no significant differences between calcitriol and doxercalciferol in bone histology or biochemical parameters.

AUTHORS' CONCLUSIONS

Bone disease, assessed by changes in PTH levels, is improved by all vitamin D preparations. However, no consistent differences between routes of administration, frequencies of dosing or vitamin D preparations were demonstrated. Although fewer episodes of high calcium levels occurred with the non-calcium-containing phosphate binder, sevelamer, compared with calcium-containing binders, there were no differences in serum phosphorus and calcium overall and phosphorus values were reduced to similar extents. All studies were small with few data available on patient-centred outcomes (growth, bone deformities) and limited data on biochemical parameters or bone histology resulting in considerable imprecision of results thus limiting the applicability to the care of children with CKD.

The consequences of pediatric renal transplantation on bone metabolism and growth

PURPOSE OF REVIEW

During childhood, growth retardation, decreased final height and renal osteodystrophy are common complications of chronic kidney disease (CKD). These problems remain present in patients undergoing renal transplantation, even though steroid-sparing strategies are more widely used. In this context, achieving normal height and growth in children after transplantation is a crucial issue for both quality of life and self-esteem. The aim of this review is to provide an overview of pathophysiology of CKD-mineral bone disorder (MBD) in children undergoing renal transplantation and to propose keypoints for its daily management.

RECENT FINDINGS

In adults, calcimimetics are effective for posttransplant hyperparathyroidism, but data are missing in the pediatric population. Fibroblast growth factor 23 levels are associated with increased risk of rejection, but the underlying mechanisms remain unclear. A recent meta-analysis also demonstrated the effectiveness of rhGH therapy in short transplanted children.

SUMMARY

In 2013, the daily clinical management of CKD-MBD in transplanted children should still focus on simple objectives: to optimize renal function, to develop and promote steroid-sparing strategies, to provide optimal nutritional support to maximize final height and avoid bone deformations, to equilibrate calcium/phosphate metabolism so as to provide acceptable bone quality and cardiovascular status, to correct all metabolic and clinical abnormalities that can worsen both bone and growth (mainly metabolic acidosis, anemia and malnutrition), promote good lifestyle habits (adequate calcium intake, regular physical activity, no sodas consumption, no tobacco exposure) and eventually to correct native vitamin D deficiency (target of 25-vitamin D >75 nmol/l).

Calcium balance in pediatric online hemodiafiltration: Beware of sodium and bicarbonate in the dialysate

BACKGROUND

Online hemodiafiltration (oHDF) is increasingly used in children; we treated 28 children since 2009, adapting this technique to pediatric patients.

METHODS

In this service evaluation audit, we assessed plasma electrolytes to evaluate the evolution of total (tCa) and ionized (iCa) during a session, as well as dialysate calcium (dCa) concentrations.

RESULTS

Using a 1.25 mmol Ca/L-dialysate, both tCa and iCa decreased during the session, with iCa falling below 1.1 mmol/L in 4/5 patients. In contrast, using a 1.5 mmol Ca/L-dialysate, iCa remained normal in all patients. Major discrepancies were observed between the expected and the measured dCa: 1.25 vs. 1.01 (0.83-1.04), and 1.5 vs. 1.47 (0.85-1.75) mmol/L, respectively (results presented as median [range]). These differences were explained by the modality of reconstituting dialysate: increasing bicarbonates and/or decreasing sodium requested in the dialysate decreases calcium extraction from the acid preparation. Proof of concept was given when requesting in an "ex-vivo" setting modifications in the requested sodium and bicarbonate in dialysate directly on the Fresenius machine.

CONCLUSION

Nephrologists should be aware that "high bicarbonate and/or low sodium" requirements in oHDF decrease calcium in the dialysate.

Intestinal phosphate transport: a therapeutic target in chronic kidney disease and beyond?

Hyperphosphatemia is a serious complication of late-stage chronic kidney disease (CKD), contributing to the increased cardiovascular morbidity and mortality seen in this patient group. Results from retrospective studies suggest that small increases in serum phosphate concentration, within the normal or near-normal range, also correlate with increased cardiovascular morbidity and mortality and have led to the suggestion that detection and preventative treatment of positive phosphate balance is important in healthy individuals as well as in those with CKD. Phosphate homeostasis is maintained by the crosstalk between intestinal phosphate absorption and renal phosphate excretion; however, relatively little is known about the mechanisms of intestinal phosphate transport. Our current understanding is that the intestinal type II sodium phosphate cotransporter, NaPi-IIb, plays a significant role in absorption. It may also be involved in the sensing of dietary phosphate composition and the release of hormonal factors that modulate renal phosphate reabsorption to achieve phosphate balance. Interestingly, studies using NaPi-IIb knockout mice with adenine-induced CKD show only partial attenuation of hyperphosphatemia, suggesting that an additional sodium-independent pathway is involved in phosphate absorption. The aim of this review is to discuss our current knowledge of the processes and role of the intestine in phosphate homeostasis and to provide evidence that this organ could be targeted for the treatment of hypophosphatemia and hyperphosphatemia.

Mineral metabolism in European children living with a renal transplant: a European society for paediatric nephrology/european renal association-European dialysis and transplant association registry study

BACKGROUND AND OBJECTIVES

Data on mineral metabolism in pediatric renal transplant recipients largely arise from small single-center studies. In adult patients, abnormal mineral levels are related to a higher risk of graft failure. This study used data from the European Society for Paediatric Nephrology/European Renal Association-European Dialysis and Transplant Association Registry to study the prevalence and potential determinants of mineral abnormalities, as well as the predictive value of a disturbed mineral level on graft survival in a large cohort of European pediatric renal transplant recipients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This study included 1237 children (0-17 years) from 10 European countries, who had serum calcium, phosphorus, and parathyroid hormone measurements from 2000 onward. Abnormalities of mineral metabolism were defined according to European guidelines on prevention and treatment of renal osteodystrophy in children on chronic renal failure.

RESULTS

Abnormal serum phosphorus levels were observed in 25% (14% hypophosphatemia and 11% hyperphosphatemia), altered serum calcium in 30% (19% hypocalcemia, 11% hypercalcemia), and hyperparathyroidism in 41% of the patients. A longer time since transplantation was associated with a lower risk of having mineral levels above target range. Serum phosphorus levels were inversely associated with eGFR, and levels above the recommended targets were associated with a higher risk of graft failure independently of eGFR.

CONCLUSIONS

Abnormalities in mineral metabolism are common after pediatric renal transplantation in Europe and are associated with graft dysfunction.

The demise of calcium-based phosphate binders-is this appropriate for children?

In children with chronic kidney disease (CKD) optimal control of mineral and bone disorder (MBD) is essential not only for the prevention of debilitating skeletal complications and for achieving adequate growth, but also for preserving long-term cardiovascular health. The growing skeleton is particularly vulnerable to the effects of CKD, and bone pain, fractures and deformities are common in children on dialysis. Defective bone mineralisation has been linked with ectopic calcification, which in turn leads to significant morbidity and mortality. Despite national and international guidelines for the management of CKD-MBD, the management of mineral dysregulation in CKD can be extremely challenging, and a significant proportion of patients have calcium, phosphate or parathyroid hormone levels outside the normal ranges. Clinical and experimental studies have shown that, in the setting of CKD, low serum calcium levels are associated with poor bone mineralisation, whereas high serum calcium levels can lead to arterial calcification, even in children. The role of calcium in CKD-MBD is the focus of this review.

Antibacterial responses by peritoneal macrophages are enhanced following vitamin D supplementation

Patients with chronic kidney disease (CKD), who usually display low serum 25-hydroxyvitamin D (25D) and 1,25-dihydroxyvitamin D (1,25D), are at high risk of infection, notably those undergoing peritoneal dialysis (PD). We hypothesized that peritoneal macrophages from PD patients are an important target for vitamin D-induced antibacterial activity. Dialysate effluent fluid was obtained from 27 non-infected PD patients. Flow cytometry indicated that PD cells were mainly monocytic (37.9±17.7% cells CD14+/CD45+). Ex vivo analyses showed that PD cells treated with 25D (100 nM, 6 hrs) or 1,25D (5 nM, 6 hrs) induced mRNA for antibacterial cathelicidin (CAMP) but conversely suppressed mRNA for hepcidin (HAMP). PD cells from patients with peritonitis (n = 3) showed higher baseline expression of CAMP (18-fold±9, p<0.05) and HAMP (64-fold±7) relative to cells from non-infected patients. In 12 non-infected PD patients, oral supplementation with a single dose of vitamin D2 (100,000 IU) increased serum levels of 25D from 18±8 to 41±15 ng/ml (p = 0.002). This had no significant effect on PD cell CD14/CD45 expression, but mRNA for HAMP was suppressed significantly (0.5-fold, p = 0.04). Adjustment for PD cell CD14/CD45 expression using a mixed linear statistical model also revealed increased expression of CAMP (mRNA in PD cells and protein in effluent) in vitamin D-supplemented patients. These data show for the first time that vitamin D supplementation in vitro and in vivo promotes innate immune responses that may enhance macrophage antibacterial responses in patients undergoing PD. This highlights a potentially important function for vitamin D in preventing infection-related complications in CKD.

[Online hemodiafiltration in children and hypoparathyroidism: a single-centre series of cases]

BACKGROUND

Due to technical requirements and cost, hemodiafiltration (HDF) is not widely used in pediatrics. We have been using online HDF (oHDF) since 2009 and we observed low parathyroid hormone (PTH) levels despite the accurate management of CKD-MBD.

METHODS

We reviewed the medical charts and parameters of mineral metabolism assessed on a before/after session basis in the 6 children undergoing chronic oHDF in our centre.

RESULTS

We observed low (<80pg/mL) PTH levels in all 6 patients and very low (<45pg/mL) PTH levels in 5, two of them presenting with pathological fractures. These low PTH levels were reversed after decreasing calcium concentration to 1.25 mmol/L in the dialysate, suggesting that high-efficiency oHDF may expose children to calcium during sessions in a too important amount when using 1.5 mmol/L dialysates. Last, C-terminal FGF23 levels before sessions were relatively low (<1600RU/mL), with a 32% clearance by oHDF.

CONCLUSION

PTH levels should be closely monitored in pediatric oHDF and solutions with a calcium concentration of 1.25 mmol/L should be used as first line in these patients.

Quality and consistency of clinical practice guidelines for the management of children on chronic dialysis

BACKGROUND

Clinical practice guidelines aim to improve the quality of care, yet for users of guidelines it is often not clear how these guidelines were developed and whether the recommendations are robust. We aimed to identify all current published guidelines for the management of children on chronic dialysis, assess the quality of their development and evaluate consistency among their recommendations.

METHODS

We searched Medline (1948 to January 2012), and relevant websites of guideline development programmes. Three reviewers appraised all 17 identified guidelines with the Appraisal of Guidelines for Research and Evaluation (AGREE) II instrument.

RESULTS

The guidelines were developed by five different professional associations. The overall mean AGREE II score from seven Kidney Disease Outcomes Quality Initiatives (KDOQI) guidelines was considered sufficient (mean scores 64-75%), and from all other 10 guidelines poor (29-44%). Five out of seven KDOQI guidelines scored weak on applicability. We found important inconsistencies between recommendations concerning initiation of renal replacement therapy, management of haemoglobin level and the use of mupirocin to prevent exit-site infections.

CONCLUSIONS

While the recently developed KDOQI guidelines meet the modern quality standards, advice for implementation of these recommendations is lacking. There is an urgent need for international collaboration and coordination to ensure that the management of children on chronic dialysis is informed by relevant and high-quality evidence.

Clinical practice recommendations for the care of infants with stage 5 chronic kidney disease (CKD5)

BACKGROUND

To provide recommendations for the care of infants with stage 5 chronic kidney disease (CKD5).

SETTING

European Paediatric Dialysis Working Group.

DATA SOURCES

Literature on clinical studies involving infants with CKD5 (end stage renal failure) and consensus discussions within the group.

RECOMMENDATIONS

There has been an important change in attitudes towards offering RRT (renal replacement therapy) to both newborns and infants as data have accumulated on their improved survival and long-term outcomes. The management of this challenging group of patients differs in a number of ways from that of older children. The authors have summarised the basic recommendations for treating infants with CKD5 in order to support the multidisciplinary teams who endeavour on this difficult task.

The skeletal consequences of growth hormone therapy in dialyzed children: a randomized trial

BACKGROUND AND OBJECTIVE

The effects of recombinant human growth hormone on renal osteodystrophy are unknown; thus, the effects of growth hormone (GH) on bone histomorphometry were assessed in pediatric patients with ESRD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Thirty-three patients who underwent bone biopsy between July 1994 and May 1999 were randomly assigned to therapy with or without GH. Patients were stratified by bone formation rate; all patients with high bone turnover received intraperitoneal calcitriol. Serum biochemical values were obtained monthly, and bone biopsy was repeated after 8 months.

RESULTS

Median patient age was 11.7 years (interquartile range [IQR], 7.6, 14.1 years); 45% of patients were male, and 52% were prepubertal. Median dialysis duration was 0.4 (IQR, 0.3, 0.8) year. Bone formation rate per bone surface increased from 15.0 (9.6, 21.8) to 154.6 (23.7, 174.3) μm(2)/μm(3) per year (P=0.05) in patients with low bone turnover treated with GH, decreased from 103.3 (57.0, 173.4) to 60.3 (20.3, 13.7) μm(2)/μm(3) per year in patients with high bone turnover receiving standard therapy (P=0.03), and was unchanged in the other two groups. Bone formation rates were higher with GH, irrespective of underlying bone histologic features (P=0.05). Parathyroid hormone did not differ between groups. GH therapy resulted in greater increases in height SD scores (estimated mean difference in change ± SD, 0.324±0.076; P<0.001), irrespective of underlying bone histologic features.

CONCLUSIONS

GH therapy improves height in pediatric dialysis patients, irrespective of underlying bone histologic features. Bone formation rates are higher in GH recipients, and GH therapy alters the relationship between circulating parathyroid hormone values and bone turnover.

Phosphate binders, vitamin D and calcimimetics in the management of chronic kidney disease-mineral bone disorders (CKD-MBD) in children

In order to minimize complications on the skeleton and to prevent extraskeletal calcifications, the specific aims of the management of chronic kidney disease mineral and bone disorder (CKD-MBD) are to maintain blood levels of serum calcium and phosphorus as close to the normal range as possible, thereby maintaining serum parathyroid hormone (PTH) at levels appropriate for CKD stage, preventing hyperplasia of the parathyroid glands, avoiding the development of extra-skeletal calcifications, and preventing or reversing the accumulation of toxic substances such as aluminum and β2-microglobulin. In order to limit cardiovascular calcification, daily intake of elemental calcium, including from dietary sources and from phosphate binders, should not exceed twice the daily recommended intake for age and should not exceed 2.5 g/day. Calcium-free phosphate binders, such as sevelamer hydrochloride and sevelamer carbonate, are safe and effective alternatives to calcium-based binders, and their use widens the margin of safety for active vitamin D sterol therapy. Vitamin D deficiency is highly prevalent across the spectrum of CKD, and replacement therapy is recommended in vitamin D-deficient and insufficient individuals. Therapy with active vitamin D sterols is recommended after correction of the vitamin D deficiency state and should be titrated based on target PTH levels across the spectrum of CKD. Although the use of calcimimetic drugs has been proven to effectively control the biochemical features of secondary hyperparathyroidism, there is very limited experience with the use of such agents in pediatric patients and especially during the first years of life. Studies are needed to further define the role of such agents in the treatment of pediatric CKD-MBD.

Searching the optimal PTH target range in children undergoing peritoneal dialysis: new insights from international cohort studies

The treatment of the mineral and bone disorder associated with chronic kidney disease (CKD-MBD) remains a major challenge in pediatric patients. The principal aims of therapeutic measures are not only to prevent the debilitating skeletal complications and to achieve normal growth but also to preserve long-term cardiovascular health. Serum parathyroid hormone (PTH) levels are used as a surrogate parameter of bone turnover. Whereas it is generally accepted that serum calcium and phosphate levels should be kept within the range for age, current pediatric consensus guidelines differ markedly with respect to the optimal PTH target range and operate on a limited evidence base. Recently, the International Pediatric Dialysis Network (IPPN) established a global registry collecting detailed clinical and biochemical information, including data relevant to CKD-MBD in children on chronic peritoneal dialysis (PD). This review highlights the current evidence basis regarding the optimal PTH target range in pediatric CKD patients, and re-assesses the current guidelines in view of the outcome data collected by the IPPN registry. Based on a comprehensive evaluation of CKD-MBD outcome measures in this global patient cohort, a PTH target range of 1.7-3 times the upper limit of normal (i.e. 100-200 pg/ml) appears reasonable in children undergoing chronic PD.