Osteoblastic differentiation of bone marrow mesenchymal stem cells in uremic rats

Severe secondary hyperparathyroidism (SHPT) represents a high turnover bone disease, osteitis fibrosa, but the pathogenesis of osteitis fibrosa remains to be fully elucidated. We examined the characteristics of the differentiation of bone marrow mesenchymal stem cells (BMSCs) into osteoblasts in uremic rats. We bred 5/6 nephrectomized (Nx) rats with a high phosphorus (P) diet to induce SHPT (Nx + HP), or Nx (Nx + ND) and normal rats (Nc + ND) fed a standard diet (ND). After 8 weeks, BMSCs were isolated from the femur and serum were analyzed. BMSCs underwent flow cytometric examination for the expression patterns of cell surface markers (CD90⁺, CD29⁺, CD45^-, and CD31^-). Serum creatinine (Cre) levels were significantly elevated in the Nx + NP rats compared with the Nc + NP rats. Cre levels in the Nx + HP rats were levels to those in the Nx + ND rats. Serum P and PTH levels were significantly elevated in the Nx + HP rats compared with the Nx + ND rats. Bone morphometrical analysis showed increases in both osteoid volume and eroded surfaces in the Nx + HP but not in the Nx + ND rats. The populations of harvested BMSCs were similar between all three groups. Alp, Runx2, Pth1r and Cyclin D1 mRNA expression in the BMSCs from the Nx + ND rats were significantly suppressed compared with those isolated from the Nc + ND groups. Alizarin red staining tended to be similar to the expression of these mRNA. These results suggest that the BMSCs differentiation into osteoblasts was disturbed in the uremic rats.

Anatomical distribution and number of parathyroid glands, and parathyroid function, after total parathyroidectomy and bilateral cervical thymectomy

The normal distribution of parathyroid glands is well documented. However, this study aims to evaluate the efficacy of total parathyroidectomy (TPTx) and bilateral cervical thymectomy (BCTx) for the treatment of secondary hyperparathyroidism (SHPT) through identifying the location of parathyroid glands with attention to the pattern and frequency of orthotopic and ectopic glands.Between 2013 and 2018, sixty chronic hemodialysis patients with medically refractory SHPT underwent TPTx & BCTx. The adequacy of the operation was defined by the pathological confirmation of at least 4 parathyroid glands, accompanied by an intact parathormone (iPTH) value of <60 pg/mL on postoperative day 1(POD1). Based on their anatomical localizations, four distinct sites were identified for both the upper (Zone I-IV) and lower parathyroid glands (Zone V-VIII).The mean follow-up was 15.2 ± 14.6 months. The mean iPTH values on POD1 were normal in 50 patients, with an average of 11.7 ± 14.4 pg/mL. Ten patients (16.6%) had persistent HPT after the operation, three of whom underwent complementary parathyroidectomy. The surgical success rates after first and second operations were both 83.3%. A total of 235 parathyroid glands were detected. Ninety-two percent of the upper parathyroids were located in Zones I and II. However, almost 28% of the lower parathyroids were ectopic and located in Zones VII and VIII.At least one fourth of the lower parathyroids are ectopic; for this reason, Zones VII and VIII require careful investigation during surgery. For upper parathyroids not found in Zone I-III, total thyroidectomy on the same side is recommended.

Bone metabolism, density, and geometry in postmenopausal women with vitamin D insufficiency: a cross-sectional comparison of the effects of elevated parathyroid levels

Increased levels of parathyroid hormone (PTH) may have adverse effects on bone health. In a cross-sectional design, we investigated this hypothesis among 102 postmenopausal vitamin D insufficient women. Elevated PTH was associated with altered bone geometry, decreased bone mineral density in the spine, and increased bone turnover.

INTRODUCTION

In vitamin D insufficiency, elevated parathyroid hormone (PTH) levels may contribute to adverse effect on bone. We assessed effects of PTH responses to vitamin D insufficiency on bone metabolism, density, and geometry.

METHODS

Using a cross-sectional design, we investigated 102 healthy postmenopausal women with low 25-hydroxy-vitamin D (< 50 nmol/L) levels, who had either secondary hyperparathyroidism with elevated PTH levels (> 6.9 pmol/L, N = 51) or normal PTH levels (N = 51). Bone mineral density (BMD) and bone geometry were assessed by Dual-Energy X-ray absorptiometry (DXA), quantitative computed tomography (QCT) and high-resolution peripheral QCT (HRpQCT) scans. Bone metabolism was assessed by biochemistry including bone turnover markers.

RESULTS

Levels of 25(OH)D were 38 (IQR 31-45) nmol/L with no differences between groups. PTH levels were 8.5 (IQR 7.5-9.5) in women with SHPT and 5.2 (4.4-6.6) pmol/L in women with normal PTH (p < 0.001). BMI and eGFR did not differ between groups. SHPT was associated with lower total- and trabecular bone area, lower cortical perimeter, and increased cortical area in tibia and radius. SHPT was associated with a lower weight-adjusted BMD at the lumbar spine (p < 0.05). High compared to normal PTH levels were associated with significantly lower plasma levels of 1,25(OH)₂D, phosphate, but higher levels of osteocalcin and borderline higher levels of CTx. PTH correlated to osteocalcin and CTx.

CONCLUSIONS

High PTH levels are associated with altered bone geometry, increased bone turnover, and reduced BMD at the spine. Whether an increased cortical thickness with a lower trabecular volume is an effect of PTH or not needs further elucidations.

Association of Anabolic Effect of Calcitriol with Osteoclast-Derived Wnt 10b Secretion

Canonical Wnt (Wingless/Integrated) signaling is crucial in bone development and the Wnt ligand can promote osteoblast differentiation from mesenchymal progenitor cells. Calcitriol, an active vitamin D3, is used clinically for treatment of secondary hyperparathyroidism (SHPT) in chronic kidney disease (CKD) patients. The bone effects of calcitriol in SHPT remains uncertain. We hypothesized that calcitriol improves bone mass by suppressing osteoclast activity, and simultaneously promoting Wnt ligand secretion. We designed a cross-sectional study in maintenance hemodialysis patients to explore the effects of calcitriol on different bone turnover markers and specifically emphasized the Wnt 10b levels. Then, we explored the source of Wnt 10b secretion by using osteoclasts and osteoblasts treated with calcitriol in cell culture studies. Finally, we explored the effects of calcitriol on bone microarchitectures in CKD mice, using the 5/6 nephrectomy CKD animal model with analysis using micro-computed tomography. Calcitriol promoted the growth of both trabecular and cortical bones in the CKD mice. Wnt 10b and Procollagen 1 N-terminal Propeptide (P1NP) significantly increased, but Tartrate-resistant acid phosphatase 5b (Trap 5b) significantly decreased in the calcitriol-treated maintenance hemodialysis patients. Calcitriol enhanced Wnt 10b secretion from osteoclasts in a dose-dependent manner. Treatment of SHPT with calcitriol improved the bone anabolism by inhibiting osteoclasts and promoting osteoblasts that might be achieved by increasing the Wnt 10b level.

[Update 2017 of the KDIGO guidelines on Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD). What are the real changes?]

Guidelines for the assessment, diagnosis and therapy of the alterations that characterize the CKD-MBD are an important support in the clinical practice of the nephrologist. Compared to the KDIGO guidelines published in 2009, the 2017 update made changes on some topics on which there was previously no strong evidence both in terms of diagnosis and therapy. The recommendations include the diagnosis of bone anomalies in CKD-MBD and the treatment of mineral metabolism abnormalities with particular regard to hyperphosphataemia, calcium levels, secondary hyperparathyroidism and anti-resorptive therapies. The Italian Study Group on Mineral Metabolism, in reviewing the 2017 recommendations, aimed to assess the weight of the evidence that led to this update. In fact, on some topics there has not been a substantial difference on the degree of evidence compared to the previous guidelines. The Italian Study Group emphasizes the points that may still reserve critical issues, including interpretation, and invites an evaluation that is articulated and personalized for each patient.

Cinacalcet use and the risk of cardiovascular events, fractures and mortality in chronic kidney disease patients with secondary hyperparathyroidism

With the aim to expand the randomized controlled trial evidence of cinacalcet treatment to the unselected, general chronic kidney disease (CKD) population we analysed a large inception cohort of CKD patients in the region of Stockholm, Sweden 2006-2012 (both non-dialysis, dialysis and transplanted) with evidence of secondary hyperparathyroidism (SHPT). We used marginal structural models to account for both confounding by indication and time-dependent confounding. Over 37 months, 435/3,526 (12%) initiated cinacalcet de novo. Before cinacalcet initiation, parathyroid hormone (PTH) had increased progressively to a median of 636ng/L. After cinacalcet initiation, PTH declined, as did serum calcium and phosphate. In total, 42% of patients experienced a fatal/non-fatal cardiovascular event, 32% died and 9% had a new fracture. The unadjusted cardiovascular odds ratio (OR) associated with cinacalcet treatment was 1.01 (95% confidence interval: 0.83, 1.22). In the fully weighted model, the cardiovascular odds was lower in cinacalcet treated patients (OR 0.67: 0.48, 0.93). The adjusted ORs for all-cause mortality and for fractures were 0.79 (0.56, 1.11) and 1.08 (0.59, 1.98) respectively. Our study suggests cinacalcet treatment improves biochemical abnormalities in the wider CKD population, and adds real-world support that treating SHPT with cinacalcet may have beneficial effects on cardiovascular outcomes.

Facial Changes in Adult Uremic Patients on Chronic Dialysis: Possible Role of Hyperparathyroidism

Background

Uremic patients on regular dialytic treatment (RDT) are often affected by a complex metabolic syndrome leading to osteodystrophy. Bone changes are primarily due to high bone turn over, often combined with a mineralization defect leading to increased bone fractures and bone deformities. Although rarely considered, the craniofacial skeleton represents one of the peculiar targets of this complex metabolic disease whose more dramatic pattern is a form of leontiasis ossea. This complication, although described, has never been evaluated in depth nor quantitatively assessed. In order to assess facial deformities in uremic conditions and to understand the possible relation with hyperparathyroidism, we undertook a quantitative evaluation of soft facial structures in a cohort of uremic patients undergoing RDT.

Methods

The three-dimensional coordinates of 50 soft-tissue facial landmarks were obtained by an electromagnetic digitizer in 10 male and 10 female patients with chronic renal insufficiency aged 53–81 years, and in 34 healthy individuals of the same age, ethnicity and sex. Uremic patients were enrolled according to hyperparathyroid status (PTH < 300 pg/mL and PTH > 500 pg/mL). From the landmarks, facial distances, angles and volumes were calculated according to a geometrical face model.

Results

Overall, the uremic patients had significantly larger facial volumes than the reference subjects. The effect was particularly evident in the facial middle third (maxilla), leading to an inversion of the mandibular-maxillary ratio. Facial dimensions were increased in all three spatial directions: width (skull base, mandible, nose), length (nose, mandible), and depth (mid face, mandible). The larger maxilla was accompanied by a tendency to more prominent lips (reduced interlabial angle). Some of the facial modifications (nose, lips, mandible) were significantly related to the clinical characteristics of the patients (age, duration of renal insufficiency and PTH levels).

Conclusions

This report, the first in the literature, shows that facial structures of uremic patients are enlarged in comparison with matched normal subjects and that increased bone turnover could be responsible – at least in part – for facial bone changes.

Vitamin D Deficiency and Its Influence on Bone Metabolism and Density in a Brazilian Population of Healthy Men

Vitamin D supplementation is universal for postmenopausal women, but not for elderly men, in whom osteoporosis is also commonly neglected. This study aimed to evaluate vitamin D deficiency and its association with secondary hyperparathyroidism, bone resorption, and bone density in Brazilian men. A total of 120 men, 20-93 years, were evaluated for serum calcium, phosphorus, creatinine, 25-hydroxyvitamin D (25(OH)D), parathyroid hormone, biochemical markers of bone resorption (carboxy-terminal telopeptide, carboxy-terminal peptide of type I collagen), and bone mineral density (dual-energy X-ray absorptiometry). Glomerular filtration rate (GFR) below 30 mL/min/1.73 m², chronic diseases, and medications affecting bone were the exclusion criteria. No participant reported previous low-impact fractures. In the overall population, 25(OH)D levels were below 30 ng/mL in 46.7%, and below 20 ng/mL in 27.6%. Among the 93 patients 50 years and older, 28 had osteoporosis. In those 70 years and older, the prevalence of vitamin D deficiency (42.1%), secondary hyperparathyroidism (46.4%), high bone resorption (39.6%), decreased GFR (39.2%), and osteoporosis (41.4%) was significantly higher than in the younger subjects (p < 0.005 for all comparisons). Serum parathyroid hormone increased with aging and declining GFR, but was not significantly associated with 25(OH)D or bone mineral density. There was a clear contribution of vitamin D deficiency to increased bone resorption and osteoporosis. Binary logistic regression model considering age, 25(OH)D, and bone resorption identified age ≥70 years as the main determinant of osteoporosis. Our data demonstrate a high prevalence of vitamin D deficiency in a male population living in Rio de Janeiro, and emphasize its participation on the pathogenesis of age-related bone loss. (Vitamin D deficiency and osteoporosis are common in elderly Brazilian men.).

Etelcalcetide (AMG 416), a peptide agonist of the calcium-sensing receptor, preserved cortical bone structure and bone strength in subtotal nephrectomized rats with established secondary hyperparathyroidism

Sustained elevation of parathyroid hormone (PTH) is catabolic to cortical bone, as evidenced by deterioration in bone structure (cortical porosity), and is a major factor for increased fracture risk in chronic kidney disease (CKD). Etelcalcetide (AMG 416), a novel peptide agonist of the calcium-sensing receptor, reduces PTH levels in subtotal nephrectomized (Nx) rats and in hemodialysis patients with secondary hyperparathyroidism (SHPT) in clinical studies; however, effects of etelcalcetide on bone have not been determined. In a rat model of established SHPT with renal osteodystrophy, etelcalcetide or vehicle was administered by subcutaneous (s.c.) injection to subtotal Nx rats with elevated PTH (>750pg/mL) once per day for 6weeks. Sham-operated rats receiving vehicle (s.c.) served as non-SHPT controls. Prior to treatment, significant increases in serum creatinine (2-fold), blood urea nitrogen (BUN, 3-fold), PTH (5-fold), fibroblast growth factor-23 (FGF23; 13-fold) and osteocalcin (12-fold) were observed in SHPT rats compared to non-SHPT controls. Elevations in serum creatinine and BUN were unaffected by treatment with vehicle or etelcalcetide. In contrast, etelcalcetide significantly decreased PTH, FGF23 and osteocalcin, whereas vehicle treatment did not. Cortical bone porosity increased and bone strength decreased in vehicle-treated SHPT rats compared to non-SHPT controls. Cortical bone structure improved and energy to failure was significantly greater in SHPT rats treated with etelcalcetide compared to vehicle. Mineralization lag time and marrow fibrosis were significantly reduced by etelcalcetide. In conclusion, etelcalcetide reduced bone turnover, attenuated mineralization defect and marrow fibrosis, and preserved cortical bone structure and bone strength by lowering PTH in subtotal Nx rats with established SHPT.

The intriguing connections of leptin to hyperparathyroidism

PURPOSE

Leptin has been implicated in bone metabolism, but the association with parathyroid gland function has not been fully clarified. This review aimed to summarize evidence of the association between leptin and hyperparathyroidism, both primary and secondary, elucidating the potential pathophysiologic and therapeutic consequences between leptin and parathyroid hormone, hopefully prompting the design of new studies.

RESULTS

Experimental studies indicate a positive loop between leptin and parathyroid hormone in primary hyperparathyroidism. Dissimilar, parathyroid hormone seems to inhibit leptin expression in severe secondary hyperparathyroidism. Data from clinical studies indicate higher leptin levels in patients with primary hyperparathyroidism than controls, but no association between parathyroid hormone and leptin levels, as well as a minimal or neutral effect of parathyroidectomy on leptin levels in patients with primary hyperparathyroidism. Clinical data on secondary hyperparathyroidism, mainly derived from patients with chronic kidney disease, indicate a potential inverse association between leptin and parathyroid hormone in some, but not all studies. This relationship may be affected by the diversity of morbidity among these patients.

CONCLUSIONS

Data from experimental studies suggest a different association between leptin and parathyroid hormone in primary and secondary hyperparathyroidism. Data from clinical studies are conflicting and potentially affected by confounders. More focused, well-designed studies are warranted to elucidate a potential association between leptin and parathyroid hormone, which may have specific clinical implications, i.e., targeting obesity and hyperleptinemia in patients with hyperparathyroidism.

Trajectories of CKD-MBD biochemical parameters over a 2-year period following diagnosis of secondary hyperparathyroidism: a pharmacoepidemiological study

OBJECTIVES

To define groups of patients according to the changes of biochemical parameters, that is, serum calcium, phosphate and parathyroid hormone (PTH), over a 2-year follow-up period using group-based multi-trajectory modeling (GBMM) among a cohort of dialysis patients with newly diagnosed secondary hyperparathyroidism (SHPT) (ie, PTH≥500 ng/L for the first time) and to compare their patient characteristics and treatments.

DESIGN

Pharmacoepidemiological study.

SETTING

In the 12 dialysis units located in the French region of Lorraine.

PARTICIPANTS

A total of 269 dialysis patients with newly diagnosed SHPT were prospectively included from December 2009 to May 2012 and followed-up for 2 years.

RESULTS

We identified four distinct trajectory groups: 'rapid PTH drop' experiencing a rapid and sharp decrease (over weeks) in PTH level associated with decreasing phosphate level within normal range (n=34; 12.7%), 'gradual PTH decrease' experiencing a gradual and continuous decrease (over months) in PTH level and maintaining phosphate at a middle level throughout the study (n=98; 36.4%), 'slow PTH decrease with high phosphate' experiencing a slow decrease in PTH level associated with a relatively high phosphate level (n=105; 39.0%) and 'uncontrolled SHPT' with high levels of PTH and phosphate throughout the study (n=32; 11.9%). Patients in the 'uncontrolled SHPT' group were significantly (p<0.00001) younger than patients in other groups. Kidney Disease Improving Global Outcomes (KDIGO) targets for PTH, phosphate and calcium were reached simultaneously for 14.9% of patients at baseline and 16.7% at the end of the study. Patients were given cinacalcet more frequently at months 3 and 6 in the 'rapid PTH drop' and at month 24 in the 'uncontrolled SHPT' groups.

CONCLUSIONS

Over 2 years following a new SHPT diagnosis, a younger age and a higher rate of alkaline phosphatase were associated to a continuous uncontrolled SHPT. Patients with the lowest PTH at the end of the follow-up tended to receive more often cinacalcet.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov number, NCT02888639, post results.

[The pathophysiology of secondary hyperparathyroidism]

Secondary hyperparathyroidism (SHPT) is characterized by the acceleration of bone turnover due to the over-secretion of parathyroid hormone, which is accompanied with parathyroid hyperplasia. The pathogenesis includes the reduced production of calcitriol due to the elevated serum fibroblast growth factor 23 (FGF23) level to maintain phosphate (P) homeostasis, and its resultant hypocalcemia. Although the mechanism parathyroid glands sense P remains unknown, the expressions of calcium (Ca) sensing receptor and vitamin D receptor, which sense serum level of Ca and calcitriol respectively, down-regulate in chronic kidney disease. The rapture of feedback system including these, contributes to the development of SHPT.

[Contemporary opinions on the diagnosis and treatment of secondary hyperparathyroidism]

Secondary hyperparathyroidism is one of the most common hormonal disorders associated with a chronic kidney disease. The main causes of this disease are associated with renal failure hyperphosphatemia, hypocalcemia, and active form of vitamin D deficiency. The progressive secondary hyperparathyroidism leads to a series of complications known as a mineral and bone disorder in a chronic kidney disease. In the treatment of secondary hyperparathyroidism the most important role is played by stabilization of calcium-phosphate metabolism (through proper diet regimen, the use of phosphate binders) and reducing the synthesis and secretion of parathyroid hormone by the administration of calcimimetics and preparations of vitamin D. In the event of failure of conservative treatment complete or partial parathyroid resection should be considered.

Treatment Failure of Active Vitamin D Therapy in Chronic Kidney Disease: Predictive Factors

BACKGROUND

In patients with chronic kidney disease (CKD), impaired renal function leads to decreased vitamin D levels, which causes an increase in parathyroid hormone (PTH) production and contributes to the development of secondary hyperparathyroidism (SHPT). This may result in adverse clinical effects such as bone disorders, vascular calcification, cardiovascular disease, and increased mortality. Current treatment practices and associated outcomes with active vitamin D treatment in patients with CKD were reviewed with the objective to assess parameters (such as PTH and serum calcium levels) that may be used to define the failure of vitamin D treatment.

SUMMARY

Reports based on observational data have noted improved outcomes with active vitamin D treatment (calcitriol, paricalcitol, alfacalcidol, or doxercalciferol) in patients with CKD. Criteria for the identification of active vitamin D treatment failure are unclear from current guidelines, although up to 50% of patients may experience treatment failure eventually because of development of hypercalcemia or resistant SHPT, characterized by an elevated intact PTH (iPTH) level despite treatment. We propose a definition of vitamin D treatment failure as iPTH >600 pg/ml after 6 months of intravenous active vitamin D treatment and corrected total calcium serum levels >10.2 mg/dl, and review factors that may predict the response to vitamin D treatment. Key Message: Active vitamin D treatment failure is an important challenge in clinical practice. The aim of the proposed definition is to suggest a possible framework for hypothesis generation and to encourage further research into this common problem.

Characteristics of hyperparathyroid states in the Canadian multicentre osteoporosis study (CaMos) and relationship to skeletal markers

CONTEXT

PTH is an essential regulator of mineral metabolism; PTH hypersecretion may result in hyperparathyroidism including normocalcaemic, primary and secondary hyperparathyroidism.

OBJECTIVE

To examine the characteristics of participants with hyperparathyroid states and the relationship to bone mineral density (BMD).

DESIGN AND PARTICIPANTS

A cross-sectional study of 1872 community-dwelling men and women aged 35+ years (mostly Caucasian) with available serum PTH from Year 10 Canadian Multicentre Osteoporosis Study follow-up (2005-07). PTH was determined using a second-generation chemiluminescence immunoassay.

OUTCOME MEASURES

L1-L4, femoral neck and total hip BMD.

RESULTS

We established a PTH reference range (2·7-10·2 pmol/l) based on healthy participants (i.e. normal serum calcium, serum 25-hydroxyvitamin D, kidney function and body mass index, who were nonusers of antiresorptives, glucocorticoids and diuretics and not diagnosed with diabetes or thyroid disease). Participants with PTH levels in the upper reference range (5·6-10·2 pmol/l), representing a prevalence of 10·7%, had lower femoral neck and total hip BMD, by 0·030 g/cm(2) [95% confidence interval: 0·009; 0·051] and 0·025 g/cm(2) (0·001; 0·049), respectively, than those with levels 2·7-5·6 pmol/l. Participants with normocalcaemic and secondary hyperparathyroidism also had lower total hip BMD than those with levels 2·7-5·6 pmol/l, and CaMos prevalences of normocalcaemic, primary and secondary hyperparathyroidism were 3·3%, 1·4% and 5·2%, respectively.

CONCLUSION

We found reduced BMD in participants with accepted hyperparathyroid states but also a notable proportion of other participants that might benefit from having lower PTH levels.

Multiple brown tumors and pathologic patellar fracture in a patient with secondary hyperparathyroidism

A 79-year-old woman presents with left anterior knee pain after a fall.

Total parathyroidectomy with autotransplantation for a rare disease derived from uremic secondary hyperparathyroidism, the uremic leontiasis ossea

SUMMARY

We described six uremic leontiasis ossea (ULO) patients who underwent total parathyroidectomy with autotransplantation. ULO demonstrated more a systemic disease than a simple craniofacial deformation. The surgery seemed an effective treatment to alleviate secondary hyperparathyroidism and to improve patients' quality of life. ULO may have a high postoperative recurrence tendency.

INTRODUCTION

ULO is a rare disease derived from uremic secondary hyperparathyroidism (SHPT). Previous studies mostly focused on the craniofacial deformations. This study aims to investigate the systemic features of the disease and the surgical outcomes.

METHODS

The present study retrospectively assessed six ULO patients who underwent total parathyroidectomy (TPTX) with autotransplantation (AT). Follow-up data were recorded. The follow-up status was considered as "effectiveness" if serum intact parathyroid hormone (iPTH) levels were <150 pg/mL in the first 3 days after surgery, or as "recurrence" if serum iPTH gradually increased >300 pg/mL during follow-up in patients whose status was initially considered as "effectiveness".

RESULTS

Craniofacial deformations, short stature, thoracocyllosis, spine malformations, osteodynia, and muscle weakness were observed in all patients. Abnormal pulmonary functions were observed in five patients. After surgery, one patient died from respiratory failure. Surgery was effective in the remaining five patients with relieved osteodynia and stopped craniofacial deformation. A mean follow-up of 7.6 (4 to 12) months was available. Three patients suffered from recurrence of hyperparathyroidism originating from autografts.

CONCLUSIONS

Our data suggests that ULO is not only a simple disease with craniofacial malformations but is a severe systemic disease leading to increased surgical risks. TPTX with AT seems an effective treatment to relieve SHPT and to improve quality of life. ULO may have a high postoperative recurrence tendency.

The clinical course of treated hyperparathyroidism among patients receiving hemodialysis and the effect of cinacalcet: the EVOLVE trial

CONTEXT

The clinical course of secondary hyperparathyroidism (sHPT) in patients on hemodialysis is not well described, and the effect of the calcimimetic cinacalcet on disease progression is uncertain.

OBJECTIVE

Our objective was to describe 1) the clinical course of sHPT in patients treated with phosphate binders and/or vitamin D sterols and 2) the impact of cinacalcet on the occurrence of severe unremitting HPT, defined by the persistence of markedly elevated PTH concentrations together with hypercalcemia or parathyroidectomy (PTX).

DESIGN AND SETTING

This was a randomized, double-blind, placebo-controlled, global, multicenter clinical trial.

PATIENTS

Of 5755 patients screened with moderate to severe sHPT, 3883 patients on hemodialysis were included in the trial.

MAIN OUTCOME MEASURES

Outcomes included PTX; severe, unremitting HPT; and use of commercial cinacalcet (a protocol violation).

INTERVENTION

Intervention was cinacalcet (30-180 mg daily) or placebo for up to 64 months.

RESULTS

In the 1935 patients randomized to placebo, 278 patients (14%) underwent PTX (median PTH 1872 pg/mL within the previous 12 weeks from surgery). Age, sex, geographic region, co-morbidity, calcium-containing phosphate binder use, and baseline serum calcium, phosphorus, and PTH concentrations were associated with PTX. Commercial cinacalcet was started in 443 (23%) patients (median PTH 1108 pg/mL before treatment began). Severe unremitting HPT developed in 470 patients (24%). In a multivariable Cox model, the relative hazard (comparing patients randomized to cinacalcet versus placebo) of severe unremitting HPT was 0.31 (95% confidence interval = 0.26-0.37). The relative hazard differed little when adjusted by baseline clinical characteristics.

CONCLUSIONS

Severe unremitting HPT develops frequently in patients on hemodialysis despite conventional therapy, and cinacalcet substantially reduces its occurrence.

Vascular calcification in a young patient with end-stage renal disease

Vascular calcification in children with long-standing dialysis is a unique phenomenon. Hyperphosphataemia and hyperparathyroidism are the major pathogenic risk factors. We describe a young patient with end-stage renal disease diagnosed since childhood and underwent prolonged dialysis therapy. He was admitted for recurrent episodes of acute joint pain. Investigations confirmed diffuse periarticular, vascular, and intracardiac calcifications which were rarely seen in the young population. He underwent parathyroidectomy and incidentally found to have a co-existing papillary carcinoma of thyroid. After parathyroidectomy, serial X-rays showed resorption of these calcifications.

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.

Renal and extrarenal actions of Klotho

Klotho is a single-pass transmembrane protein highly expressed in the kidney. Membrane Klotho protein acts as a co-receptor for fibroblast growth factor-23. Its extracellular domain is shed from the cell surface and functions as an endocrine substance that exerts multiple renal and extrarenal functions. An exhaustive review is beyond the scope and length of this article; thus, only effects with pertinence to mineral metabolism and renoprotection are highlighted here. Klotho participates in mineral homeostasis via interplay with other calciophosphoregulatory hormones (parathyroid hormone, fibroblast growth factor-23, and 1,25-[OH]2 vitamin D3) in kidney, bone, intestine, and parathyroid gland. Klotho also may be involved in acute and chronic kidney disease development and progression. Acute kidney injury is a temporary and reversible state of Klotho deficiency and chronic kidney disease is a sustained state of systemic Klotho deficiency. Klotho deficiency renders the kidney more susceptible to acute insults, delays kidney regeneration, and promotes renal fibrosis. In addition to direct renal effects, Klotho deficiency also triggers and aggravates deranged mineral metabolism, secondary hyperparathyroidism, vascular calcification, and cardiac hypertrophy and fibrosis. Although studies examining the therapeutic effect of Klotho replacement were performed in animal models, it is quite conceivable that supplementation of exogenous Klotho and/or up-regulation of endogenous Klotho production may be a viable therapeutic strategy for patients with acute or chronic kidney diseases.

Calcium-mediated parathyroid hormone suppression to assess progression of secondary hyperparathyroidism during treatment among incident dialysis patients

CONTEXT

Parathyroid gland function is affected adversely by tissue hyperplasia and gland enlargement in hyperparathyroidism.

OBJECTIVE

We examined the effects of 2 treatment strategies on the progression of secondary hyperparathyroidism using measurements of the nonsuppressible component of calcium-regulated PTH secretion as an index of parathyroid mass.

DESIGN, SUBJECTS, AND INTERVENTION

In this randomized, open-label study, subjects managed with hemodialysis for >3 but <12 months before entering the trial (mean, 7.2 months) who had baseline plasma PTH levels >300 pg/mL received cinacalcet and low-dose vitamin D sterols (Cin-D, n = 153) or larger, varying doses of calcitriol, or other vitamin D analogs (Flex-D, n = 151). Study drug doses were adjusted periodically based on PTH and serum total calcium determinations.

MAIN OUTCOME MEASURES

The exploratory endpoint was calcium-regulated PTH release, assessed using a standardized PTH suppression test before and after 52 weeks of treatment and 4 weeks after withdrawing treatment. PTH and serum total calcium were measured before hemodialysis using high-calcium (3.5 mEq/L or 1.75 mmol/L) dialysate and after 150 and 180 minutes.

RESULTS

Mean (95% confidence interval) nonsuppressible calcium-regulated PTH release at baseline did not differ between Cin-D, 33.4% (25.9%, 40.9%), and Flex-D, 28.1% (23.2%, 32.9%). Corresponding values after 52 weeks of treatment were 34.3% (29.7%, 38.9%) and 42.0% (32.7%, 51.3%), not significant, and did not change measurably in either group when reevaluated 4 weeks after treatments were withdrawn.

CONCLUSION

Disease progression over 12 months was not documented using a PTH suppression test in this population. Calcium-mediated PTH suppression was maintained fully, however, in Cin-D despite reductions in serum total calcium concentration, whereas values did not increase in Flex-D despite substantial increases in serum calcium.

The efficacy of cinacalcet combined with conventional therapy on bone and mineral metabolism in dialysis patients with secondary hyperparathyroidism: a meta-analysis

Cinacalcet, the first calcimimetic to be approved for the treatment of secondary hyperparathyroidism (SHPT) in the chronic kidney disease patients, offers a novel therapeutic approach to SHPT. The aim of this meta-analysis is to access the efficacy and safety of cinacalcet on bone and mineral metabolism disorders in the dialysis patients with SHPT. Randomized controlled trials on cinacalcet combined with vitamin D and/or phosphate binders in the dialysis patients with SHPT were identified in Pubmed, Sciencedirect, and the Cochrane library. Data were analyzed with RevMan software. We compared the proportion of patients achieving the biochemical targets recommended by the Kidney Disease Outcomes Quality Initiative (KDOQI) guidelines and the incidence of adverse events between the cinacalcet and control groups. Six trials involving 2,548 patients were included. A greater proportion of patients in the cinacalcet group compared with the conventional group achieved the KDOQI targets. The relative risks (RRs) were parathyroid hormone (PTH) (RR = 3.51, 95 % CI: 2.38-5.17), calcium (RR = 2.04, 95 % CI: 1.76-2.37), phosphorus (RR = 1.15, 95 % CI: 0.83-1.60), and calcium-phosphorus product (Ca × P) (RR = 1.41, 95 % CI: 1.18-1.69), the number of patients simultaneously achieving the KDOQI targets for PTH + Ca × P was also greater (RR = 3.89, 95 % CI: 2.36-6.41), with p < 0.001 for each. The most common adverse events were nausea, vomiting, diarrhea, and hypocalcemia, which had a higher incidence in the cinacalcet group, but were usually mild to moderate in severity and transient. Compared with conventional therapy, treatment with cinacalcet results in more patients achieving KDOQI targets and offers an effective and safety therapeutic option for controlling mineral and bone disorders in the dialysis patients with SHPT.

Hip fracture patients in India have vitamin D deficiency and secondary hyperparathyroidism

SUMMARY

This study evaluated the parameters of bone mineral homeostasis including 25(OH)D and PTH in 90 Indian patients with hip fracture and 90 controls. Hypovitaminosis D, secondary hyperparathyroidism, and biochemical osteomalacia was present in 77, 69, and 50 % patients, respectively, significantly higher compared to controls. Vitamin D deficiency is an important risk factor for hip fracture.

INTRODUCTION

The prevalence of vitamin D deficiency is not well known in hip fracture patients from India. Therefore, the present study was conducted to evaluate the parameters of bone mineral homeostasis including 25(OH)D and intact PTH in hip fracture from North India.

METHODS

Ninety consecutive patients with hip fracture and similar number of age- and sex-matched controls were enrolled in the study. The fasting venous samples were analyzed for 25-hydroxyvitamin D (25-OHD), intact parathyroid hormone (PTH), alkaline phosphatase (ALP), calcium, and phosphorus. Vitamin D deficiency was defined as serum 25-OHD of <20 ng/dl.

RESULTS

The mean age of hip fracture subjects was 65.9 ± 12.6 which was comparable in men and women. Majority of study subjects were women (70 women and 20 men). The serum 25(OH)D and calcium levels were significantly lower, whereas the intact PTH and ALP levels were significantly higher in patients compared to controls. There was significant negative correlation between serum 25(OH)D and PTH. In the hip fracture group, 76.7 % of the subjects had vitamin D deficiency, and 68.9 % had secondary hyperparathyroidism. In the control group, vitamin D deficiency and elevated PTH levels were seen in 32.3 and 42.2 %, respectively.

CONCLUSION

About three fourths of hip fracture patients have vitamin D deficiency, and two thirds have secondary hyperparathyroidism. Therefore, the serum 25-OHD level may be a useful index for the assessment of risk of hip fracture in India.

Secondary and tertiary hyperparathyroidism

We reviewed the etiology and management of secondary and tertiary hyperparathyroidism. Secondary hyperparathyroidism is characterized by an increase in parathyroid hormone (PTH) that is appropriate and in response to a stimulus, most commonly low serum calcium. In secondary hyperparathyroidism, the serum calcium is normal and the PTH level is elevated. Tertiary hyperparathyroidism is characterized by excessive secretion of PTH after longstanding secondary hyperparathyroidism, in which hypercalcemia has ensued. Tertiary hyperparathyroidism typically occurs in men and women with chronic kidney disease usually after kidney transplant. The etiology and treatment of secondary hyperparathyroidism is relatively straightforward whereas data on the management of tertiary hyperparathyroidism is limited to a few small trials with short follow-up.

Parathyroidectomy leads to decreased blood lead levels in patients with refractory secondary hyperparathyroidism

OBJECTIVE

Secondary hyperparathyroidism (SHPT) is characterized by high bone turnover and may result in increased release of lead (Pb) from bone stores. Parathyroidectomy (PTX) drastically changes bone remodeling. This study investigated the effects of PTX on the levels of blood lead (blood Pb) in patients with refractory SHPT.

METHODS

The study included 30 patients on long-term hemodialysis (HD) who underwent PTX in the nephrology units of two Taiwanese hospitals. Changes in serum levels of intact parathyroid hormone (iPTH), bone-specific alkaline phosphatase (BAP), type 5b tartrate-resistant acid phosphatase (TRAP), total calcium (tCa), and blood Pb were analyzed.

RESULTS

After PTX, serum iPTH was markedly decreased while serum BAP was progressively increased and peaked 2weeks after PTX. Serum TRAP levels were progressively decreased during the 4week follow-up period. Serum tCa and blood Pb levels decreased sharply immediately after PTX. There was a positive correlation between the percentage of decrease in tCa and blood Pb at one day after PTX. Further analysis indicated a significant positive correlation between levels of blood Pb and serum iPTH (r=0.378, p<0.001), blood Pb and serum TRAP (r=0.180, p<0.05), and a negative correlation between blood Pb and serum BAP (r=-0.205, p<0.05).

CONCLUSION

PTX effectively suppressed the elevated levels of blood Pb and serum bone remodeling markers, which are common features of SHPT. In addition to decreased Pb release from bone, an increased store of Pb in bone may play a role in decreasing serum blood Pb levels. These findings suggest that patients undergoing PTX for refractory SHPT should strictly avoid environmental exposure to Pb.

Does cinacalcet HCl, an oral calcimimetic agent for the treatment of secondary hyperparathyroidism, improve arterial stiffness in patients on continuous ambulatory peritoneal dialysis?

Vascular calcification (VC) and arterial stiffness (AS) are major contributors to cardiovascular disease, and in chronic kidney disease, VC and AS are correlated. Disorders of calcium and phosphate metabolism contribute to the progression of VC and to increases in AS. The efficacy of cinacalcet (CIN) in reducing AS in patients on continuous ambulatory peritoneal dialysis (CAPD) has not been determined. The present study enrolled 19 CAPD patients (12 women, 7 men; mean age: 62.2 +/- 3.6 years) with serum intact parathyroid hormone (iPTH) greater than 500 ng/dL (mean value: 675 +/- 106 ng/dL) in whom daily oral treatment with CIN 25 mg was started. If administration of CIN for 3 months failed to reduce the level of iPTH to less than 300 ng/dL, the dose of CIN was increased to 50 mg daily. Before the start of CIN and at 3 years after the start of CIN, pulse wave velocity (PWV) was determined. In 11 patients, levels of iPTH were reduced to less than 300 ng/dL; levels in the rest of the patients remained high. We observed no significant differences in PWV before CIN and at 3 years after CIN start (1856 +/- 198 cm/s vs. 1726 +/- 187 cm/s). Multivariate regression analysis of PWV demonstrated that both systolic blood pressure and changes in serum levels of phosphate contributed to decreases in PWV In patients receiving CAPD, VC and AS might be the result of higher systolic blood pressure and increased serum levels of phosphate.

Insufficient bilateral femoral subtrochanteric fractures in a patient receiving imatinib mesylate

We present a case of insufficient bilateral femoral subtrochanteric fractures in a patient who was treated with imatinib mesylate, an anticancer drug, for 1 year after a diagnosis of chronic myelogenous leukemia (CML). A 60-year-old woman presented with bilateral thigh pain for 6 months. A plain radiograph revealed bilateral progressive insufficient fractures on the subtrochanteric areas of the femurs. MRI of the femurs revealed incomplete stress fractures and no evidence of bone metastasis on either femur. Bone densitometry showed normal T-scores around the hip joint and spine. The patient had normal serum levels of calcium, vitamin D derivatives, and thyroid hormones. Serum phosphate levels were decreased, and parathyroid hormone levels were increased. Serum osteocalcin and urinary N-telopeptide of collagen cross-links (NTx) were both decreased. A bone biopsy demonstrated normocellular marrow without leukemic cells. A histomorphometric evaluation of her bones revealed reduced bone turnover despite secondary hyperparathyroidism. The serum markers for bone metabolism and histomorphometric evaluations in this patient suggest that the drug may have an effect on bone metabolism. These effects could be seen for both bone formation and resorption: this could result in impaired bone mineralization, a severely suppressed bone turnover rate, insufficient fractures, and bone necrosis, which are sometimes seen with long-term use of bisphosphonates. To our knowledge, this is the first case of an insufficient bilateral femoral shaft fracture that is potentially related to the use of imatinib mesylate in a patient with CML. Careful examination of bone metabolism should be performed in patients with CML because imatinib mesylate treatment is a lifelong process.

Left-shifted relation between calcium and parathyroid hormone in obesity

BACKGROUND

A condition resembling secondary hyperparathyroidism (HPT), including raised levels of PTH and normal levels of serum calcium, has been reported in obesity. A plausible reason may be vitamin D deficiency, but conflicting data have been reported.

OBJECTIVE

Our objective was to investigate calcium homeostasis in obese individuals with emphasis on the function of the parathyroid glands.

DESIGN AND INTERVENTION

Morbidly obese patients (mean body mass index=46.6+/-6) were examined for their status of calcium homeostasis. A subset was thoroughly investigated with calcium-citrate (CiCa) clamping.

PATIENTS

Of 108 morbidly obese patients, 11 underwent CiCa clamping as well as 21 healthy volunteers of normal weight and 15 with primary HPT (pHPT). Large patient cohorts of normal individuals and pHPT patients were also used as comparisons.

OUTCOME MEASURES AND RESULTS

All obese individuals had normal serum calcium and creatinine levels. Mean levels of 25-OH-vitamin D3 in serum were low, 53 nmol/liter (reference range 75-250 nmol/liter). Mean intact plasma PTH was 5.1 pmol/liter (reference range 1.1-6.9 pmol/liter). There was a significant positive correlation between PTH and duration of obesity. CiCa clamping in obese subjects revealed a remarkably high sensitivity for calcium and a left-shifted relation between plasma calcium and PTH (set point) compared with the normal population. CiCa clamping in pHPT patients demonstrated a right-shifted PTH-Ca curve.

CONCLUSION

Although vitamin D levels in the obese individuals were low, few displayed overt signs of secondary HPT. The CiCa clamping implied a disturbance in the calcium homeostasis comparable to early renal insufficiency, with a left-shifted Ca-PTH curve and a lower set point compared with the normal population.

Vitamin D in kidney disease: pathophysiology and the utility of treatment

Vitamin D physiology has gained more importance and publicity than any of its counterparts in the water- and fat-soluble vitamin groups combined. This is partly because vitamin D deficiency is still widely prevalent in the developed world and the beneficial effects are thought to extend beyond the regulation of calcium and phosphorus homeostasis alone. Vitamin D deficiency becomes even more important in the various stages of chronic kidney disease (CKD); CKD itself is also on the increase. How vitamin D physiology is altered in CKD and how the various treatment modalities can alter the morbidity and mortality associated with CKD is the topic of discussion for this article.

Survey of attitudes of physicians toward the current evaluation and treatment of chronic kidney disease-mineral and bone disorder (CKD-MBD)

We aimed in this study to determine the opinion of the medical directors of dialysis centers in the Kingdom of Saudi Arabia (KSA) about the updates of strategies for evaluation and treatment of chronic kidney disease-mineral and bone Disorder (CKD-MBD). A questionnaire was sent to medical directors of 174 dialysis centers in the KSA between July and November 2009. The questionnaire was opinion based and comprised the prevalence of the CKD-MBD, strategies of therapy and indications of cinacalcet, a new therapy in the CKD patients. A total of 154 medical directors of the 174 (88.5%), who are the therapeutic decision-makers for 10100 (89%) dialysis patients, answered the questionnaire. There were 84 respondents (54%) who believed that the parathormone (PTH) blood levels initially increase at a glomerular filtration rate (GFR) < 30%. There were 80 (53%) respondents who believed that changes of phosphorus (PO4) and calcium (Ca) blood levels are initially observed at GFR < 30 mL/min. The majority of respondents, 115 (77%), 116 (80%), 95 (66%), and 134 (90%) currently have observed increased prevalence of vascular calcifications, adynamic bone disease, PTH > 500 pmol/L, and elevated Ca blood levels, respectively, only in the minority of advanced CKD. However, 88 (58%) respondents observed increased prevalence of elevated PO4 blood levels in the majority of new dialysis and advanced CKD patients. There were 137 (89%) respondents who believed from the current published evi-dence that CKD-MBD may result in increased morbidity (e.g. fractures) and mortality (e.g. cardiovascular) in advanced CKD and new dialysis patients. However, only 41 (27%) respondents follow the PTH levels in their patients every 2-3 months, while 81(53%) follow it every 6 months. There were 127 (83%), 129 (84%), 114 (75%) respondents who would start vitamin D (vit D) in dialysis and CKD patients for hypocalcemia, high PTH, and vit D 1,25 deficiency, respectively. However, only 51 (34%) respondents would start vit D therapy for vit D 25 deficiency. There were 98 (75%), 73 (57%) 74 (59%), and 88 (68%) respondents who claimed that they could achieve control of calcium levels alone, control of PO4 levels alone PTH levels alone , and all parameters of CKD-MBD in > 50% of their patients, respectively. There were 126 (82%) and 126 (82%) respondents who agreed to the indications of the cinacalcet that include refractory secondary hyperparathyroidism of dialysis patients to vit D and diet and phosphate binders together, and when surgical parathyroidectomy is contraindicated or fail in this population, respectively. However, 127 (83%) and 139 (91%) respondents disagreed to the indications that include indiscriminate prescription to all CKD patients or off label to some early CKD patients, respectively. We conclude that the medical directors of the active dialysis centers in Saudi Arabia are well aware of the morbidity and mortality caused by the CKD-MBD in addition to the indications of vit D and phosphate binders and cinacalcet therapy. However, the study suggests inadequate assessment of the prevalence, patterns of CKD-MBD, and results of intervention in the CKD patients such as treatment of vit D 25 deficiency, and knowledge of the availability of cinacalcet for the treatment of CKD-MBD. More local studies and guidelines are required to disseminate information about the current patterns of CKD-MBD for better approach to the management of this disorder in the kidney centers in this country.

Calcium-sensing receptor as a potential modulator of vascular calcification in chronic kidney disease

Secondary hyperparathyroidism plays an important role in the mineral and bone disorders that are associated with cardiovascular events in chronic kidney disease patients. Secondary hyperparathyroidism is partially due to decreased calcium-sensing receptor expression in parathyroid glands in these patients. Calcimimetics have been demonstrated to be particularly useful to control parathyroid hormone (PTH) oversecretion and concomitantly reduce serum Ca2+ and phosphorus levels in dialysis patients. However, recent findings highlight the role of calcium-sensing receptor allosteric coactivators as inhibitors of the development of vascular calcification. Calcimimetics could prevent the vascular calcification process by controlling not only PTH overfunction, hypercalcemia and hyperphosphatemia, but also by directly modulating vascular calcium-sensing receptors. In this review, the authors describe the recently demonstrated role played by calcium-sensing receptor and its modulation by calcimimetics on uremia-induced vascular calcification.

[Pathophysiology of secondary hyperparathyroidism: the role of FGF23 and Klotho]

Secondary hyperparathyroidism is a complex metabolic alteration secondary to chronic kidney disease (CKD). Reduction of 1,25(OH)2D3 synthesis is the first derangement, followed by an increase in PTH, and, lastly, calcium and phosphate modifications. Vitamin D is a hormone whose actions take place through a specific receptor, the vitamin D receptor (VDR), which is ubiquitous. Accordingly, heterogeneous biological effects can be added to the classical effects on mineral bone metabolism. In the pathophysiology of secondary hyperparathyroidism, an important role is also played by alterations of calcium transport, which is under the control of two receptors: VDR and CaSR (calcium-sensing receptor). The expression of these receptors is reduced during CKD. Recent findings have allowed to identify a new hormonal system, the FGF23-Klotho axis, that integrates the old and simple, but now inadequate, PTH-Vit D axis. FGF23 is a circulating factor produced by osteocytes that inhibits renal phosphate reabsorption and 1-alpha-hydroxylase activity. As such, FGF23 is involved in phosphate homeostasis and its serum levels increase along with the progression of CKD. Interestingly, FGF23 has very low affinity for its receptor and requires the activity of Klotho, an anti-aging gene, to become active. These new actors allow us to identify a bone-kidney axis, whose real physiological importance is still under evaluation.

Renal secondary hyperparathyroidism in dogs

The parathyroid glands secrete parathyroid hormone (PTH), which is important for maintaining calcium homeostasis. Parathyroid gland hyperplasia and subsequent hyperparathyroidism can occur secondary to chronic renal failure in dogs, resulting in significant alterations in calcium metabolism. Renal secondary hyperparathyroidism is a complex, multifactorial syndrome that involves changes in circulating levels of calcium, PTH, phosphorus, and 1,25-dihydroxycholecalciferol (calcitriol). An increased PTH level can have deleterious effects, including soft tissue mineralization, fibrous osteodystrophy, bone marrow suppression, urolithiasis, and neuropathy. Dietary phosphorus restriction, intestinal phosphate binders, and calcitriol supplementation may slow the progression of renal disease and decrease PTH concentrations in animals with secondary hyperparathyroidism; however, the prognosis for these animals is guarded to poor.

Relationship between plasma fibroblast growth factor-23 concentration and bone mineralization in children with renal failure on peritoneal dialysis

CONTEXT

Fibroblast growth factor (FGF)-23 is produced in bone, and circulating levels are markedly elevated in patients with end-stage kidney disease, but the relationship between plasma levels of FGF-23 and bone histology in dialysis patients with secondary hyperparathyroidism is unknown.

OBJECTIVE

The aim of the study was to evaluate the correlation between plasma levels of FGF-23 and bone histology in pediatric patients with end-stage kidney disease who display biochemical evidence of secondary hyperparathyroidism.

DESIGN

We performed a cross-sectional analysis of the relationship between plasma FGF-23 levels and bone histomorphometry.

SETTING

The study was conducted in a referral center.

STUDY PARTICIPANTS

Participants consisted of forty-nine pediatric patients who were treated with maintenance peritoneal dialysis and who had serum PTH levels (1st generation Nichols assay) greater than 400 pg/ml.

INTERVENTION

There were no interventions.

MAIN OUTCOME MEASURE

Plasma FGF-23 levels and bone histomorphometry were measured.

RESULTS

No correlation existed between values of PTH and FGF-23. Bone formation rates correlated with PTH (r = 0.44; P < 0.01), but not with FGF-23. Higher FGF-23 concentrations were associated with decreased osteoid thickness (r = -0.49; P < 0.01) and shorter osteoid maturation time (r = -0.48; P < 0.01).

CONCLUSIONS

High levels of FGF-23 are associated with improved indices of skeletal mineralization in dialyzed pediatric patients with high turnover renal osteodystrophy. Together with other biomarkers, FGF-23 measurements may indicate skeletal mineralization status in this patient population.

Immunomodulatory effects of secondary hyperparathyroidism on circulating CD4+ and CD8+ T-lymphocytes in chronic renal failure patients

The immunomodulatory effects of parathyroid hormone (PTH) in patients with end stage renal disease (ESRD) is controversial. This study was carried out to investigate the effect of PTH levels on the circulating CD4+, CD8+ T cell counts (%) in patients with chronic renal failure (CRF) on regular hemodialysis ((HD). The study included 22 patients with serum levels of PTH < 300 pg/ml (group 1), 18 patients with PTH > 300 pg/ml (group II) and 10 age and sex matched normal controls (group III). Chemiluminescence and flowcytometry assays were performed for determination of serum PTH levels and T cell subset counts respectively. The mean (%) of total lymphocyte, CD4+, CD8+ and CD4\CD8 ratio of group I were (81.68+/- 9.38), (52.00+/-6.24), (27.13+/- 6.31) and (1.99+/-0.42) respectively, as compared to (73.83+/-13.30), (46.05+/-8.59), (23.05+/-4.63) and (2.03+/-0.41) respectively in group II. Values of group I and II were significantly (P<0.001) lower than controls (88.50 +/- 6.02), (63.30 +/- 6.44), (36.80 +/- 6.44) and (1.76+/-0.36) respectively. In group II, the reduction was significantly (P<0.001) prominent in patients with high PTH levels, with significant inverse correlations (P<0.001) between PTH and % of total lymphocyte (r= -0.93), CD4+ (r= -0.74) and CD8+ % (r=-0.69). In conclusion, increased level of PTH in CRF patients on hemodialysis is associated with lymphopenia and reduction in CD4+ & CD8+ subsets of T cells. Monitoring circulating PTH levels in such patients can restore their immune competence.

Parathyroidectomy improves the quality of sleep in maintenance hemodialysis patients with severe hyperparathyroidism

Sleeping disorders are very common in patients with chronic kidney disease on dialysis (CKD5D) and are an emerging risk factor able to predict mortality. Parathyroid hormone (PTH) although considered a pivotal uremic toxin has rarely been associated with sleep disorders in uremia. In a study from our laboratory PTH concentrations failed to distinguish patients with sleep disorders from those without. In a study performed by Chou et al a 97% prevalence of insomnia was found in patients undergoing hemodialysis requiring parathyroidectomy. Surgery reduced PTH and increased sleeping hours within 3 months. The aim of this study was to study the effects of parathyroidectomy on the sleep disorders of insomniacs on maintenance hemodialysis. The study was performed in 16 insomniac patients on maintenance hemodialysis who successfully underwent surgery with autotransplantation of autologous parathyroid tissue (40 mg) under the skin of the forearm. Patients (5 F and 11 M) were studied from 1 month before surgery to 1 year after. Sleep disorders were assessed by means of a 27-item questionnaire--Sleep Disorder questionnaire (SDQ)--that identified sleeping disorders according to Diagnostic and Statistical Manual of Mental Disorders - IV Edition (DSM-IV) criteria. The Charlson Comorbidity Index (CCI) was also measured along with systolic and diastolic blood pressure, Hb, PTH, Ca, P. A 95.5% prevalence of sleep disorders was found pre operatively. Patients slept 4.90+/-1.2 hours, Ca averaged 10.09+/-0.54 mg/dL, Phosphate 5.5+/-1.93, CCI 9.8+/-1.1, PTH 1498+/-498 ng/mL. After 1 year follow-up 2 out 16 patients had normal sleep, 6 out 16 patients had subclinical sleep disorders and 8 remained insomniacs (p=0.008, Mc Nemar Test for paired data, insomniacs vs. no disturbance + subclinical disorders). Sleeping hours increased up to 6.0+/-1.24 (p<0.05), PTH was normalized, the Charlson Comorbidity Index was reduced (p<0.05) as were plasma calcium and phosphate (p<0.01). The study indicates that insomnia in patients with severe hyperparathyroidism on maintenance hemodialysis is ameliorated by parathyroidectomy.

The role of IGF-I and IGFBP-1 status and secondary hyperparathyroidism in relation to osteoporosis in elderly Swedish women

IGFBP-1 showed a strong inverse relation to the BMD values. The IGF-I values had a significant positive relation to the BMD values at all sites with the exception of the lumbar spine. The use of loop diuretics was a more important cause of secondary hyperparathyroidism than vitamin D status.

INTRODUCTION

Our aim was to investigate among elderly women the relationship to osteoporosis of calcium-regulating hormones and insulin-like growth factor-I (IGF-I) and insulin-like growth factor binding protein-1 (IGFBP-1).

METHODS

A population-based cross-sectional study of 350 elderly women (mean age 73 years). Measurements of bone mineral density (BMD) of the left hip, lumbar spine and heel and risk markers for osteoporosis were studied.

RESULTS

The BMD values showed significant inverse relationship with the values of IGFBP-1 at all sites of measurement and significant positive relationship with the values of IGF-I at all sites with the exception of the lumbar spine. There was no significant association between the values of BMD and the values of 25-hydroxy vitamin D (25(OH)D). The use of loop diuretics was strongly and significantly associated with elevated levels of PTH >65 pg/ml (OR 4.4, P < 0.001).

CONCLUSIONS

The anabolic growth factor IGF-I and its modulating binding protein IGFBP-1 showed a stronger association with the BMD values than the calcium regulating hormones 25(OH)D and PTH. In this study the use of loop diuretics was a more important cause of secondary hyperparathyroidism than vitamin D status.

[The incidence of tertiary hyperparathyroidism after renal transplantation]

INTRODUCTION

Tertiary hyperparathyroidism (3 degrees HPT) is a condition characterized by autonomous secretion of parathyroid hormone (PTH) which develops as a consequence of secondary hyperparathyroidism in patients with chronic renal failure. Severe cases of 3 degrees HPT are treated with parathyroidectomy (Ptx). The purpose of this study was to uncover the incidence of 3 degrees HPT and frequency of Ptx after renal transplantation (Tx). Furthermore, we wanted to identify parameters that predicted the development of 3 degrees HPT and the prognosis.

MATERIALS AND METHODS

The study included 189 consecutive patients who underwent Tx at Odense University Hospital from 1/1/2000 to 12/31/2004. We defined 3 degrees HPT as at least one elevated measurement of P-PTH concurrent with elevated S-Ca2+. Elevated S-Ca2+ was defined as at least 5 consecutive, elevated measurements from 14 days to six months after Tx.

RESULTS

A total of 59 patients (39%) developed 3 degrees HPT after Tx and 13 (22%) of these underwent Ptx. Diabetes mellitus type-1 (DM type-1) significantly increased the risk of 3 degrees HPT. The median duration from Tx to Ptx was 223 (33-911) days. In non-Ptx patients, the median duration of hypercalcemia due to 3 degrees HPT was 37 months.

CONCLUSION

3 degrees HPT occurred in approximately 1/3 of the patients and DM-type-1 increased the risk. Without Ptx regression of 3 degrees HPT was seen even after several years' duration.

Sca-1+ Hematopoietic Cell–based Gene Therapy with a Modified FGF-2 Increased Endosteal/Trabecular Bone Formation in Mice

This study assessed the feasibility of using an ex vivo stem cell antigen-1-positive (Sca-1(+)) cell-based systemic fibroblast growth factor-2 (FGF-2) gene therapy to promote endosteal bone formation. Sca-1(+) cells were used because of their ability to home to, and engraft into, the bone marrow cavity. The human FGF-2 gene was modified to increase protein secretion and stability by adding the bone morphogenic protein (BMP)-2/4 hybrid signal sequence and by mutating two key cysteines. Retro-orbital injection of Sca-1(+) cells transduced with a Moloney leukemia virus (MLV)-based vector expressing the modified FGF-2 gene into sub-lethally irradiated W(41)/W(41) recipient mice resulted in long-term engraftment, more than 100-fold elevation in serum FGF-2 level, increased serum bone-formation markers, and massive endosteal bone formation. In recipient mice showing very high serum FGF-2 levels (>2,000 pg/ml), this enhanced endosteal bone formation was so robust that the marrow space was filled with bony tissues and insufficient calcium was available for the mineralization of all the newly formed bone, which led to secondary hyperparathyroidism and osteomalacia. These adverse effects appeared to be dose related. In conclusion, this study provided compelling test-of-principle evidence for the feasibility of using an Sca-1(+) cell-based ex vivo systemic FGF-2 gene therapy strategy to promote endosteal bone formation.

Direct injection of calcitriol or its analog improves abnormal gene expression in the hyperplastic parathyroid gland in uremia

AIMS

In this study, we investigated the effects of direct injection (DI) of calcitriol or maxacalcitol into the hyperplastic parathyroid gland (PTG) on altered gene expression related to the advanced status of secondary hyperparathyroidism (SHPT).

METHODS

Sprague-Dawley rats were 5/6-nephrectomized (uremic) or sham-operated (normal). In each uremic rat, one of the bilateral PTG was treated by DI of calcitriol (PTG(CAL)) or maxacalcitol (PTG(OCT)), and the other gland was treated with control solution (PTG(CONT)). The PTG were evaluated for levels of expression of various mRNA and immunohistochemical staining of proliferating cell nuclear antigen (PCNA).

RESULTS

Significant differences in levels of expression of mRNA and PCNA were confirmed between the uremic and normal groups. In PTG(CAL) and PTG(OCT), expressions of almost all mRNA and PCNA were significantly improved; both agents were able to normalize the abnormalities of the uremic PTG, in contrast to the baseline and individual PTG(CONT). However, the difference in effect between PTG(CAL) and PTG(OCT) was only small.

CONCLUSION

Our results suggest that very high concentrations of calcitriol or maxacalcitol in the PTG improve abnormal gene expression and proliferation activity of parathyroid cells, and might explain the better control of SHPT using the DI technique.

Bone growth during daily or intermittent calcitriol treatment during renal failure with advanced secondary hyperparathyroidism

Calcitriol is a standard therapy for secondary hyperparathyroidism in chronic renal failure. We evaluated whether the effect of daily or intermittent calcitriol administration is more efficient in enhancing bone growth in renal failure with advanced secondary hyperparathyroidism in weanling 5/6 nephrectomized rats loaded with phosphorus to induce severe secondary hyperparathyroidism. The animals were treated daily or three times weekly with calcitriol for 4 weeks but the total weekly dose of calcitriol was the same. Although calcitriol increased the serum calcium, it did not lower parathyroid hormone (PTH) or improve tibia and body length. Animals with renal failure and advanced secondary hyperparathyroidism had decreased PTH/PTHrP, which was accompanied by an increase in the cyclin kinase inhibitor p57(Kip2). Calcitriol treatment upregulated the PTH/PTHrP receptor but also increased inhibitors of cell proliferation such as p21(Waf1/Cip1), IGFBP3, and FGFR3. Calcitriol also enhanced markers of chondrocyte differentiation, such as IGF1, Vitamin D receptor, FGF23, and bone morphogenetic protein-7. Receptor activator of nuclear factor-kappabeta ligand levels improved with calcitriol treatment but without changes in osteoprotegerin suggesting an enhancement of osteo/chondroclastogenesis and mineralization. Overall, both daily and intermittent calcitriol had similar effects on endochondral bone growth in phosphorus-loaded rats with renal failure.

[Resistance to vecuronium bromide induced muscle relaxation in a patient with chronic renal failure and secondary hyperparathyroidism]

We report resistance to vecuronium bromide (Vb) induced muscle relaxation for general anesthesia in a patient with chronic renal failure (CRF) and secondary hyperparathyroidism (HPT). An 81-year-old man (body weight : 52 kg) diagnosed with bladder carcinoma was scheduled for a total cystectomy. In the operating room, standard monitors were applied except for a nerve stimulator. After epidural catheter had been secured, anesthesia was induced with propofol 80 mg and Vb 5 mg. In spite of administration of these drugs and supplying 5% sevoflurane for 4 minutes, spontaneous respiration was observed. Then, propofol 50 mg and Vb 3 mg were added and lidocaine aerosol 8% was sprayed topically to oropharyngolaryngeal structures. No movement of the vocal cord was observed through the laryngoscope and the patient was intubated smoothly, but the patient did cough and move a little. The surgery was concluded uneventfully. Although the total amount of Vb administration was 14 mg in 3 hr anesthesia time, he was awake rapidly and extubated sooner than expected. We suspect that resistance to Vb has been caused in part by secondary HPT and it appears necessary to take care when administering Vb in CRF patients with secondary HPT, especially at the induction of general anesthesia.