Clinical Practice Guideline for the Management of Secondary Hyperparathyroidism in Chronic Dialysis Patients

Hyperparathyroidism in chronic kidney disease patients: an update on current pharmacotherapy

INTRODUCTION

Secondary hyperparathyroidism is the most common abnormalities of mineral metabolism in chronic kidney disease (CKD), which causes bone disease and vascular calcification, leading to increased risk of mortality.

AREAS COVERED

The aim of this review is to provide an overview of pharmacological therapies for secondary hyperparathyroidism, based on current understanding of the disease.

EXPERT OPINION

The initial event in the pathogenesis of secondary hyperparathyroidism is the phosphorus overload per nephron that lead to the secretion of a new phosphaturic hormone, fibroblast growth factor 23 from the bone. Such an abnormality develops very early in CKD, even without hyperphosphatemia. When hyperphosphatemia develops, phosphate binders are prescribed in many CKD patients. Non-calcium containing binders are gaining popularity because of less risk of excess calcium load; however, no specific superiority in patient-level outcomes has been fully established yet. For the direct control of parathyroid hormone secretion, cinacalcet hydrochloride has become widespread in addition to vitamin D receptor activators. As adverse events related to these therapeutic agents occur occasionally, however, and better adherence is one of the most important determinants of the benefits of the drugs, fewer adverse events as well as more potent therapeutic effects should be aimed in the development of new agents in future.

Mineral metabolic abnormalities and mortality in dialysis patients

The survival rate of dialysis patients, as determined by risk factors such as hypertension, nutritional status, and chronic inflammation, is lower than that of the general population. In addition, disorders of bone mineral metabolism are independently related to mortality and morbidity associated with cardiovascular disease and fracture in dialysis patients. Hyperphosphatemia is an important risk factor of, not only secondary hyperparathyroidism, but also cardiovascular disease. On the other hand, the risk of death reportedly increases with an increase in adjusted serum calcium level, while calcium levels below the recommended target are not associated with a worsened outcome. Thus, the significance of target levels of serum calcium in dialysis patients is debatable. The consensus on determining optimal parathyroid function in dialysis patients, however, is yet to be established. Therefore, the contribution of phosphorus and calcium levels to prognosis is perhaps more significant. Elevated fibroblast growth factor 23 levels have also been shown to be associated with cardiovascular events and death. In this review, we examine the associations between mineral metabolic abnormalities including serum phosphorus, calcium, and parathyroid hormone and mortality in dialysis patients.

Long-term treatment of hyperphosphatemia with bixalomer in Japanese hemodialysis patients

Bixalomer is a nonabsorbable polymer that binds phosphate in the gastrointestinal tract and lowers the serum phosphate level by inhibiting phosphate absorption. The safety and efficacy of long-term bixalomer treatment were assessed in Japanese hemodialysis patients with hyperphosphatemia. This was a multicenter open-label study with a 48-week treatment period. The main efficacy endpoints were the serum phosphate level and rate of achieving the target serum phosphate range (3.5-6.0 mg/dL). Bixalomer was initiated at a dose of 1.5 g/day, which was increased to a maximum of 7.5 g/day depending on the serum phosphate response. Of 248 subjects who started treatment, 179 completed the study. The mean serum phosphate level decreased over time and remained around 5.5 mg/dL from weeks 16 to 48. The target serum phosphate level was reached in >50% of subjects by week 7 and was maintained in 65.2% to 75.9% until week 48. The incidence of adverse events and adverse drug reactions was 94.4% and 29.4%, respectively. There was a potential relationship with the study drug for four serious adverse events (ischemic colitis, hemorrhagic intestinal diverticulum, esophageal ulcer, and acute cholecystitis), which occurred in one patient each. Constipation was the most common adverse drug reaction (21.0%). Most adverse events and adverse drug reactions occurred soon after starting administration, and their incidence did not increase during long-term treatment. Bixalomer did not reduce the bicarbonate level or promote metabolic acidosis. Bixalomer is clinically useful for the long-term treatment of hyperphosphatemia.

Parathyroid enlargement at dialysis initiation in patients with chronic kidney diseases

The kidney chiefly maintains homeostasis of water, electrolytes, and other solutions. When kidney function is reduced, mineral metabolism is disrupted. Mineral and bone disorder in patients with chronic kidney disease associates with increased cardiovascular risk and mortality; however, management of chronic kidney disease-mineral and bone disorder in predialysis patients remains controversial. This study investigates the association between parathyroid enlargement at dialysis initiation and hyperparathyroidism management in dialysis patients. We enrolled 72 patients at dialysis initiation in this study. Using parathyroid sonography, we categorized patients based on presence (detected group; N = 18) or absence (undetected group; N = 54) of enlarged parathyroid glands and assessed the clinical characteristics and laboratory findings. A literature review of ultrasound evaluations of secondary hyperparathyroidism was conducted. Ultrasonography revealed enlarged parathyroid glands in 18 patients (25%). Serum intact parathyroid hormone levels were high in patients with enlarged parathyroid glands; however, of the 29 patients with intact parathyroid hormone levels <240 pg/mL, four had enlarged parathyroid glands. Eight of the 29 patients with serum phosphorus and calcium levels within the optimal range had enlarged parathyroid glands. Twenty of these 29 patients were followed up at 38 ± 17 months (at least 3 months): enlarged parathyroid glands were detected in 6. During follow-up, serum intact parathyroid hormone levels were significantly higher in the detected group compared with the undetected. In conclusion, enlarged parathyroid glands are frequently detected at dialysis initiation, potentially predicting the persistence of secondary hyperparathyroidism and the need for strict management.

Prognostic utility of plasma S100A12 levels to establish a novel scoring system for predicting mortality in maintenance hemodialysis patients: a two-year prospective observational study in Japan

Background

S100A12 protein is an endogenous receptor ligand for advanced glycation end products. In this study, the plasma S100A12 level was assessed as an independent predictor of mortality, and its utility in clinical settings was examined.

Methods

In a previous cross-sectional study, plasma S100A12 levels were measured in 550 maintenance hemodialysis patients to determine the association between S100A12 and the prevalence of cardiovascular diseases (CVD). In this prospective study, the risk of mortality within a two-year period was determined. An integer scoring system was developed to predict mortality on the basis of the plasma S100A12 levels.

Results

Higher plasma S100A12 levels (≥18.79 ng/mL) were more closely associated with higher all-cause mortality than lower plasma S100A12 levels (<18.79 ng/mL; P = 0.001). Multivariate Cox proportional hazards analysis revealed higher plasma S100A12 levels [hazard ratio (HR), 2.267; 95% confidence interval (CI), 1.195–4.302; P = 0.012], age ≥65 years (HR, 1.961; 95%CI, 1.017–3.781; P = 0.044), serum albumin levels <3.5 g/dL (HR, 2.198; 95%CI, 1.218–3.968; P = 0.012), and history of CVD (HR, 2.068; 95%CI, 1.146–3.732; P = 0.016) to be independent predictors of two-year all-cause mortality. The integer score was derived by assigning points to these factors and determining total scores. The scoring system revealed trends across increasing scores for predicting the all-cause mortality [c-statistic = 0.730 (0.656–0.804)]. The resulting model demonstrated good discriminative power for distinguishing the validation population of 303 hemodialysis patients [c-statistic = 0.721 (0.627–0.815)].

Conclusion

The results indicate that plasma S100A12 level is an independent predictor for two-year all-cause mortality. A simple integer scoring system was therefore established for predicting mortality on the basis of plasma S100A12 levels.

Cinacalcet upregulates calcium-sensing receptors of parathyroid glands in hemodialysis patients

BACKGROUND

Cinacalcet hydrochloride (cinacalcet), a calcimimetic, has been shown to upregulate calcium-sensing receptor (CaSR) expression in parathyroid glands of rats with chronic renal insufficiency. However, the effect of cinacalcet on the reduced CaSR expression in human parathyroid glands remains to be elucidated.

METHODS

Four normal parathyroid glands and 71 hyperplastic parathyroid glands from 18 hemodialysis patients with refractory secondary hyperparathyroidism (SHPT) treated with (n = 10; cinacalcet group) or without (n = 8; conventional group) cinacalcet were examined immunohistochemically with a specific antibody against CaSR. The expression level of CaSR was analyzed semiquantitatively.

RESULTS

Compared with normal glands, the immunohistochemical expression of CaSR was decreased significantly in both the cinacalcet and conventional groups. In the cinacalcet group, the expression of CaSR was increased significantly compared with that in the conventional group (1.83 ± 0.14 vs. 0.87 ± 0.15, p < 0.001), even though the proportion of patients using vitamin D sterols and the mean administered dose of calcitriol equivalents were not significantly different between the two groups. The expression of CaSR was significantly decreased in the larger glands (>500 mg) compared with that in the smaller glands (<500 mg) in both groups; furthermore, it was markedly decreased in areas of nodular hyperplasia compared with diffuse hyperplasia in the cinacalcet group.

CONCLUSIONS

Our results indicate that cinacalcet upregulates the depressed expression of CaSR in hemodialysis patients with SHPT, and that insufficient expression of CaSR, especially in larger glands with advanced nodular hyperplasia, underlies the pathogenesis of SHPT in patients who are resistant to cinacalcet.

Control of mineral metabolism and bone disease in haemodialysis patients: which optimal targets?

BACKGROUND

There is a high drug treatment burden on patients receiving long-term dialysis therapy. Abnormalities of calcium and phosphate metabolism are associated with increased mortality, and attempts to correct these disturbances may improve survival.

METHODS

We prospectively evaluated the targets of the currently used Kidney Disease: Improving Global Outcomes (KDIGO) guidelines in 8377 prevalent patients receiving intermittent haemodialysis therapy in France from July 2007 to December 2009.

RESULTS

Adjusted Cox analyses showed that only one among six targets was predictive of mortality, i.e. a serum intact parathyroid hormone (iPTH) <130 pg/mL. A continuous risk analysis using fractional polynomials showed a 10% increase in hazard ratio (HR) for mortality for a serum phosphate <0.71 (2.2) and >1.98 (6.14) mmol/L (mg/dL), a non-corrected serum calcium <1.59 (6.37) and >2.41 (9.66) mmol/L (mg/dL) and a serum iPTH <100 and >1090 pg/mL.

CONCLUSION

The findings of our observational study confirm the existence of a grey zone, in which precise biochemical targets are difficult to define, with the exception of avoiding extreme values. Given the absence of intervention trials proving the clinical usefulness of phosphorus control, and pending the results of large clinical trials on the effect of optimal PTH and calcium control on hard outcomes, the present findings may help to refine future recommendations for the treatment of chronic haemodialysis patients.

A preliminary study of the potential role of FGF-23 in coronary calcification in patients with suspected coronary artery disease

OBJECTIVE

The association of fibroblast growth factor 23 (FGF-23) with vascular disease in patients with preserved renal function is not well understood. The purpose of this study was to investigate the relationship of serum FGF-23 with coronary calcification in patients without chronic kidney disease and diabetes mellitus (DM).

METHODS

A cross-sectional study was performed in 148 consecutive patients with suspected coronary artery disease who underwent 64-slice computed tomography coronary angiography for diagnosis of coronary artery disease. Patients with eGFR <60 mL/min/1.73 m(2), proteinuria, or DM were excluded. Associations of coronary calcification (evaluated by Agatston score) were examined with classical risk factors and with inflammatory markers, adipocytokines and FGF-23.

RESULTS

The median creatinine, eGFR and FGF-23 levels were 0.7 mg/dL, 74.6 mL/min/1.73 m(2), and 26 pg/mL respectively. The strongest association was found between age and Agatston score (r = 0.367, p < 0.001) in univariate logistic regression analysis. No atherogenic risk factors, including inflammatory markers and adipocytokine levels, were associated with Agatston score. Among calcium/phosphate metabolism markers, FGF-23 showed a weak but significant correlation with Agatston score (r = 0.169, p = 0.039). In multivariate linear regression analysis, age and FGF-23 (r = 0.188, p = 0.016) were independently associated with the Agatston score.

CONCLUSION

Serum FGF-23 levels were associated with coronary calcification independently of classical risk factors and of adipocytokines and inflammatory markers in patients with preserved renal function. FGF-23 may also have a direct effect on progression of coronary calcification and further studies are required to examine this issue.

Prescription patterns and mineral metabolism abnormalities in the cinacalcet era: results from the MBD-5D study

BACKGROUND AND OBJECTIVES

Prescription patterns for hemodialysis patients with secondary hyperparathyroidism have varied widely since market introduction of cinacalcet. This study examined associations between prescription patterns and subsequent laboratory values.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Using a Mineral and Bone Disorder Outcomes Study for Japanese CKD Stage 5D Patients subcohort, 1716 prevalent hemodialysis patients (4048 sets for repeated measures between January 2008 and July 2009) with an intact parathyroid hormone (iPTH) level >180 pg/ml who used intravenous vitamin D receptor activator (VDRA) without cinacalcet were selected. Prescription patterns were defined based on cinacalcet administration (starting or not) and VDRA dosage change (decreased [<-25%], stable [-25% to 25%], or increased [>25%]). Proportion differences (PDs) were determined for decreasing iPTH levels by at least one category (<180, 180-299, 300-499, and ≥500 pg/ml) and for achieving target phosphorus (3.5-6.0 mg/dl) and calcium (8.4-10.0 mg/dl) levels, adjusting for potential confounders.

RESULTS

The starting cinacalcet and increased VDRA patterns were associated with decreasing iPTH levels (PD, 0.25 and 0.13; 95% confidence intervals [95% CIs], 0.19-0.31 and 0.09-0.17, respectively); combination use had an additive association (PD, 0.34; 95% CI, 0.20-0.42). The starting cinacalcet and decreased VDRA combination was associated with simultaneously achieving target phosphorus (PD, 0.12; 95% CI: 0.04-0.20) and calcium (PD, 0.09; 95% CI, 0.01-0.17) levels.

CONCLUSIONS

Certain combinations of cinacalcet and VDRA were associated with decreasing iPTH and achieving targets for phosphorus and calcium. Combinations may prove advantageous versus VDRA alone in managing secondary hyperparathyroidism.

Serum adiponectin and bone mineral density in male hemodialysis patients

SUMMARY

Bone mineral density of the 1/3 distal radius, ultra-distal radius, and lumbar spine correlated significantly and negatively with serum adiponectin. There was a significant positive correlation between serum adiponectin and serum NTX. Thus, adiponectin may play a role in mineral and bone disorder in chronic kidney disease stage 5 dialysis (CKD 5D) patients.

INTRODUCTION

Serum adiponectin, an adipocyte-produced hormone, has been reported to correlate negatively with bone mineral density (BMD) in the general population. However, little is known about the association between adiponectin and BMD in patients with CKD.

METHODS

BMD of the 1/3 distal and ultra-distal radius, which are enriched with cortical and cancellous bone, respectively, and the lumbar spine was measured by dual X-ray absorptiometry in 114 Japanese male hemodialysis patients (age 61.0 ± 11.1 years; hemodialysis duration 6.6 ± 3.0 years; 43.9% diabetics). Serum total adiponectin, bone formation marker (bone alkaline phosphatase, BAP), and bone resorption marker (cross-linked N-telopeptide of type I collagen (NTX)) were measured.

RESULTS

The BMD of the 1/3 distal radius, ultra-distal radius, and lumbar spine correlated significantly and negatively with serum adiponectin level (r = -0.229, p = 0.014; r = -0.286, p = 0.002; r = -0.227, p = 0.013, respectively). In multiple linear regression analyses, serum adiponectin was significantly and independently associated with the BMD of the 1/3 distal radius (R(2) = 0.173, p < 0.001) and ultra-distal radius (R(2) = 0.278, p < 0.001) after adjustment of age, hemodialysis duration, body weight, %fat mass, and log [intact PTH], although it was not with the BMD of the lumbar spine. There was a significant positive correlation between serum adiponectin and serum NTX (r = 0.321, p < 0.001), although there was no significant correlation between serum adiponectin and serum BAP.

CONCLUSION

Increased levels of serum adiponectin were associated with decrease in BMD in male hemodialysis patients. Adiponectin may play a role in mineral and bone disorder, possibly in bone resorption, of patients with CKD 5D.

Potential influence of sevelamer hydrochloride on responsiveness to erythropoiesis-stimulating agents in haemodialysis patients

AIM

Vitamin D analogues, cinacalcet, and sevelamer play pivotal roles in the management of chronic kidney disease-mineral bone disorder, and are noted to have pleiotropic effects. We examined whether these agents might be associated with the responsiveness to erythropoiesis-stimulating agents (ESA).

METHODS

In this cross-sectional study including haemodialysis patients treated with ESA, we searched for clinical parameters associated with the ESA resistance index, which was calculated as the weekly ESA dose divided by the patient's haemoglobin value.

RESULTS

Among 45 patients (male: female = 28 : 17, age 68 ± 10 years, haemodialysis duration 84 ± 60 months), vitamin D analogue, cinacalcet, and sevelamer were used in 95.6%, 26.7%, and 84.4% of the patients, respectively. Univariate analysis showed significant association of the ESA resistance index with transferrin saturation rate (TSAT), vitamin D analogue dose, and sevelamer dose. In multivariate analysis, the sevelamer dose and TSAT were found to be independent determinants of the ESA resistance index.

CONCLUSION

Our preliminary data showed an independent association between sevelamer dose and the responsiveness to ESA in haemodialysis patients. Further studies are required to investigate the causal relationship between sevelamer and ESA responsiveness.

Randomized crossover study of the efficacy and safety of sevelamer hydrochloride and lanthanum carbonate in Japanese patients undergoing hemodialysis

Insufficient control of serum calcium and phosphate levels in patients undergoing hemodialysis is associated with increased mortality. As commonly used calcium-containing phosphate binders can cause arterial calcification, newly developed calcium-free phosphate binders, such as sevelamer hydrochloride (SH) and lanthanum carbonate (LC), have received much attention. We assessed the efficacy and safety of SH and LC treatment in Japanese patients undergoing hemodialysis in a prospective randomized open blinded endpoint (PROBE) crossover study. Forty-two patients were randomized to receive SH or LC for 13 weeks, with the dosages adjusted every 2 weeks, followed by treatment with the other drug for another 13 weeks. The average daily doses of SH and LC were 2971 ± 1464 mg and 945 ± 449 mg, respectively. The mean dosage ratio of SH to LC was 3.05, which was maintained throughout the treatment period. SH and LC were similarly effective at controlling serum calcium and phosphate levels in the majority of patients (78-93%). A few serious adverse events (AEs) involving the biliary system occurred during the LC treatment period, but they were not considered to be treatment-induced. Although the incidence of constipation, the most common treatment-related AE, was higher during the SH period (27% vs. 5%; P < 0.05), no difference was observed in total treatment-related AEs. This study demonstrates that SH and LC are comparable treatments for controlling serum phosphate and calcium levels, and that both compounds are safe and well-tolerated in Japanese patients undergoing hemodialysis.

Overview of regular dialysis treatment in Japan (as of 31 December 2009)

A nationwide statistical survey of 4196 dialysis facilities was conducted at the end of 2009, and 4133 facilities (98.5%) responded. The number of patients undergoing dialysis at the end of 2009 was determined to be 290 661, an increase of 7240 patients (2.6%) compared with that of 2008. The number of dialysis patients per million at the end of 2009 was 2279.5. The crude death rate of dialysis patients from the end of 2008 to the end of 2009 was 9.6%. The mean age of the new patients introduced into dialysis was 67.3 years old and the mean age of the entire dialysis patient population was 65.8 years old. Primary diseases such as diabetic nephropathy and chronic glomerulonephritis for new dialysis patients, showed a percentage of 44.5% and 21.9%, respectively. Based on the facilities surveyed, 84.2% of the facilities that responded to the questionnaire satisfied the microbiological quality standard for dialysis fluids for the Japanese Society for Dialysis Therapy (JSDT), with an endotoxin concentration of less than 0.05 EU/mL in the dialysis fluid. Similarly, 98.2% of the facilities surveyed satisfied another standard of the society of a bacterial count of less than 100 cfu/mL in the dialysis fluid. The facility survey indicated that the number of patients who were treated by blood purification by both peritoneal dialysis and extracorporeal circulation, such as hemodialysis, was 1720. Among the total number of patients, 24.8% were satisfied with the management target recommended in the treatment guidelines for secondary hyperparathyroidism. These standards are set by the JSDT, based on the three parameters, i.e. serum calcium concentration, serum phosphorus concentration, and serum intact parathyroid hormone concentration. According to the questionnaire, 9.8% of the patients were considered to have a complication of dementia.

VDRA therapy is associated with improved survival in dialysis patients with serum intact PTH ≤ 150 pg/mL: results of the Italian FARO Survey

BACKGROUND

Chronic kidney disease (CKD) patients affected by mineral bone disorders (MBD) have higher rates of all-cause and cardiovascular-related mortality. Approximately, one-third of dialysis patients have low serum parathyroid hormone (PTH) levels (≤ 150 pg/mL). However, the reason why these patients have higher mortality compared to patients with normal PTH levels has not yet been fully elucidated.

METHODS

The FARO study was performed on 2453 Italian patients followed prospectively from 28 dialysis centres over a 2-year period. Data were collected every 6 months and end points included time-to-death cumulative probability in patients with serum intact PTH (iPTH) ≤ 150 pg/mL and the effect of vitamin D receptor activation (VDRA) therapy. Kaplan-Meier curves and proportional hazards regression models stratified by PTH levels (i.e. ≤ 150 and >150 pg/mL) were used to determine cumulative probability of time-to-death and adjusted hazard ratios (HRs) for demographic, clinical and CKD-MBD treatment characteristics.

RESULTS

The cumulative probability of death was higher (P < 0.01) for patients with serum iPTH levels ≤ 150 pg/mL [25.1%, 95% confidence interval (CI): 22.1-28.5 at 18 months] versus those with serum iPTH levels within the normal range (18.0%, 95% CI: 16.1-20.1). In a model with time-dependent covariates restricted to time periods when patients had iPTH levels ≤ 150 pg/mL, lower mortality was observed in patients treated with VDRA [i.e. HR = 0.62, 95% CI: 0.42-0.92 for oral or intravenous (IV) calcitriol; HR = 0.18, 95% CI: 0.04-0.8 for IV paricalcitol] versus those not receiving any VDRA (P < 0.01) independently of other variables. Patients who received IV paricalcitol, compared with either oral or IV calcitriol, showed reduced mortality, but this was not statistically significant (HR = 0.3, 95% CI: 0.07-1.31, P = 0.11).

CONCLUSION

Results from this observational study suggest that VDRA therapy was associated with improved survival in dialysis patients, even with low serum iPTH levels.

Cost-effectiveness of cinacalcet hydrochloride for hemodialysis patients with severe secondary hyperparathyroidism in Japan

BACKGROUND

Cinacalcet effectively reduces elevated levels of parathyroid hormone (PTH) in patients with secondary hyperparathyroidism (SHPT), even those with severe disease for whom parathyroidectomy can be the treatment of choice. The objective of this study was to estimate the cost-effectiveness of cinacalcet treatment in hemodialysis patients with severe SHPT in Japan.

STUDY DESIGN

Cost-effectiveness analysis.

SETTING & POPULATION

Patients with severe SHPT (intact PTH >500 pg/mL) who were receiving hemodialysis in Japan.

MODEL, PERSPECTIVE, & TIMEFRAME

A Markov model was constructed from the health care system perspective in Japan. Patients were followed up over their lifetime. Dialysis costs were not included in the base case.

INTERVENTION

Cinacalcet as an addition to conventional treatment compared to conventional treatment alone. In both arms, patients underwent parathyroidectomy if intact PTH level was >500 pg/mL for 6 months and they were eligible for surgery.

OUTCOMES

Costs, quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratios (ICERs).

RESULTS

ICERs for cinacalcet for those who were eligible for surgery and those who were not were $352,631/QALY gained and $21,613/QALY gained, respectively. Sensitivity and scenario analyses showed that results were fairly robust to variations in model parameters and assumptions. In the probabilistic sensitivity analysis, cinacalcet was cost-effective in only 0.9% of simulations for those eligible for surgery, but in more than 99.9% of simulations for those ineligible for surgery, if society would be willing to pay $50,000 per additional QALY.

LIMITATIONS

Data for the long-term effect of cinacalcet on patient-level outcomes are limited. The model predicted rates for clinical events using data for the surrogate biochemical end points.

CONCLUSIONS

The use of cinacalcet to treat severe SHPT is likely to be cost-effective for only those who cannot undergo parathyroid surgery for medical or personal reasons.

Brachial-ankle pulse wave velocity and the cardio-ankle vascular index as a predictor of cardiovascular outcomes in patients on regular hemodialysis

Brachial-ankle pulse wave velocity (baPWV) and the cardio-ankle vascular index (CAVI) are both used to evaluate arterial stiffness. The aim of the present study is to determine whether baPWV or CAVI is superior as a marker of arterial stiffness in hemodialysis (HD) patients. Of 194 patients, 59 patients had been excluded from the study due to advanced age over 76 years old (n = 29), or abnormal ankle-brachial pressure index (ABI) (<0.90 or ≥1.30) (n = 30). We then followed the 135 patients (age: 60 ± 11 years, time on HD: 110 ± 93 months) for the 63 ± 4 (55-70) months. Thirty-two (23.7%) patients had expired, 22 of them of cardiovascular (CV) causes. There were 37 fatal and non-fatal CV events. Kaplan-Meier analysis revealed that the patients with the highest tertile of baPWV (≥16.6 m/s) had a significantly lower survival rate (P < 0.01) when compared with the second (13.4 ≤ baPWV < 16.6 m/s) and the lowest tertiles (<13.4 m/s). Cox hazards analysis after adjustment for comorbid risk factors revealed that the top tertile of baPWV was a determinant of CV death (hazards ratio [HR]: 16.9 [1.1-251.8], P < 0.05) In contrast, CAVI did not associate with CV mortality or events. These findings suggest that baPWV is superior to CAVI as a predictor of CV outcomes in patients on regular HD.

Influence of renin-angiotensin system on serum parathyroid hormone levels in uremic patients

INTRODUCTION

The aim of this study was to investigate the factors influencing serum parathyroid (PTH) levels, including medications for treating chronic kidney disease-mineral and bone metabolism disorder (CKD-MBD) in patients with end-stage renal disease.

METHODS

We enrolled 1,076 patients in nine Japanese facilities who had begun hemodialysis (HD) due to ESRD. We investigated the relationships between intact PTH (iPTH) levels and clinical parameters and medications just prior to beginning HD.

RESULTS

Significant decreases in serum iPTH levels were seen in males, in the presence of diabetes mellitus (DM), and with administration of renin-angiotensin system inhibitors (RASIs). Significant correlations were found between serum calcium and iPTH levels. In the patients administered RASIs, there was a significant decrease in serum iPTH levels with DM, male gender, and administration of active vitamin D sterols (VDs) compared with those not administered RASIs, although serum-corrected calcium levels were not different. Multiple regression analysis found gender, age, presence of DM, and serum calcium and phosphate levels to be significant contributing factors. In addition, administration of angiotensin II receptor blockers (ARBs) may also be a contributing factor to iPTH levels at the beginning HD (p = 0.050).

CONCLUSIONS

In this study, serum iPTH levels were related to administration of ARBs besides gender, age, the presence of DM and serum calcium levels. Our study suggests that the RA system involve serum iPTH levels in uremic patients.

Decreases in PTH in Japanese hemodialysis patients with secondary hyperparathyroidism: associations with changing practice patterns

BACKGROUND AND OBJECTIVES

Control of serum concentrations of calcium (Ca), phosphorus (P), and parathyroid hormone (PTH) is essential for management of secondary hyperparathyroidism (SHPT).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This is a planned interim analysis of a longitudinal cohort study. The settings are dialysis facilities in Japan. Eligible patients comprise all those who were receiving hemodialysis at one of 86 participating facilities and who have SHPT. Using data from a random sample (n = 3276) of the participants from January 2008 through June 2009, we measured changes in the percentages of patients who were within the national guideline-specified target ranges of Ca (8.4 to 10 mg/dl), P (3.5 to 6.0 mg/dl), and intact PTH (iPTH) (60 to 180 pg/ml), and changes in prescriptions of drugs targeting SHPT. We used regression models to identify factors affecting the achievement of the guideline-specified targets.

RESULTS

There were no notable changes in the percentage of patients who were within the guideline for Ca, P, or both. The percentage who were within the iPTH guideline increased from 14.5% to 43.3% (P < 0.001). There were no remarkable changes in the percentage of patients receiving vitamin D or phosphate binders. The percentage who received cinacalcet increased from 0% to 29%. Prescription of cinacalcet was associated with improvement or target-achievement for iPTH and for Ca by 16.8 percentage points (95% CI: 8.1 to 17.0) and by 12.6 percentage points (13.7 to 19.9), respectively.

CONCLUSIONS

In the routine care of hemodialysis patients, increasing use of cinacalcet was associated with better control of SHPT.

Cinacalcet treatment and serum FGF23 levels in haemodialysis patients with secondary hyperparathyroidism

BACKGROUND

Elevated fibroblast growth factor 23 (FGF23) is associated with adverse clinical outcomes and development of secondary hyperparathyroidism (SHPT) refractory to active vitamin D. Cinacalcet hydrochloride is effective in treating SHPT, but little is known as to whether treatment with cinacalcet alters these levels and whether pretreatment FGF23 levels predict response to this therapy.

METHODS

We measured serum full-length FGF23 levels in 55 haemodialysis patients, who participated and completed the 52-week, multicentre, open-label single-arm trial that examined the effectiveness of cinacalcet for treating SHPT. In the study, alteration of vitamin D dosage was not permitted except for the case in which serum calcium could not be managed by calcium carbonate adjustment alone.

RESULTS

After 12 weeks of cinacalcet treatment, FGF23 levels decreased significantly concomitantly with a significant reduction in intact parathyroid hormone (PTH) levels. These responses were sustained >52 weeks. In multivariate regression analyses, changes from baseline in serum FGF23 were associated with changes in serum calcium and phosphorus but not with intact PTH at each time point of measurements (Week-12, Week-24 and Week-52). Baseline FGF23 was not associated with the likelihood of achieving an intact PTH <180 pg/mL at the study end.

CONCLUSIONS

Cinacalcet lowers serum FGF23 in haemodialysis patients with SHPT independently of the effects of active vitamin D. Pretreatment FGF23 cannot predict treatment response to cinacalcet in this setting. The precise mechanism of FGF23 reduction by cinacalcet and its clinical impact on outcomes in patients remain to be investigated.

Clinical efficacy and cost-effectiveness of lanthanum carbonate as second-line therapy in hemodialysis patients in Japan

BACKGROUND AND OBJECTIVES

Lanthanum carbonate (LC) is a nonaluminum, noncalcium phosphate binder that is effective for hyperphosphatemia in dialysis patients. However, its efficacy and cost-effectiveness as second-line therapy have not been fully examined.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We first conducted a multicenter, open-label, 16-week clinical trial to examine the effect of additive LC in 116 hemodialysis patients who had uncontrolled hyperphosphatemia with conventional phosphorus-lowering therapy alone. Based on these clinical data, a state transition model was developed to evaluate the benefits and costs associated with LC as second-line therapy. Reduced risks for cardiovascular morbidity and mortality among patients treated with LC arise through more of the population achieving the target phosphorus levels. Uncertainty was explored through sensitivity analysis.

RESULTS

After 16 weeks of additive LC treatment, mean serum phosphorus levels decreased from 7.30 ± 0.90 to 5.71 ± 1.32 mg/dl, without significant changes in serum calcium or intact parathyroid hormone levels. A subsequent cost-effectiveness analysis showed that compared with conventional treatment, additive LC incurred an average additional lifetime cost of $22,054 per person and conferred an additional 0.632 quality-adjusted life years (QALYs). This resulted in an incremental cost-effectiveness ratio of $34,896 per QALY gained. Applying a cost-effectiveness threshold of $50,000 per QALY, a probabilistic sensitivity analysis showed that additive LC had a 97.4% probability of being cost-effective compared with conventional treatment.

CONCLUSIONS

Our results indicate that the use of LC as second-line therapy would be cost-effective among hemodialysis patients with uncontrolled hyperphosphatemia in Japan.

Mineral metabolism management in hemodialysis patients with secondary hyperparathyroidism in Japan: baseline data from the MBD-5D

BACKGROUND/AIMS

The Mineral and Bone Disorder Outcomes Study for Japanese CKD Stage 5D Patients (MBD-5D) is a multicenter, prospective observational study of hemodialysis patients with secondary hyperparathyroidism (SHPT) in Japan, where the national guideline recommends targets for serum calcium (8.4-10.0 mg/dl), phosphorus (3.5-6.0 mg/dl), and intact parathyroid hormone (PTH) (60-180 pg/ml).

METHODS

The MBD-5D involved patients who were receiving hemodialysis for more than 3 months and met at least one of the following conditions: having intact PTH levels >180 pg/ml, or receiving intravenous vitamin D receptor activators (VDRAs) or oral VDRA analog. This report describes the baseline characteristics of the study participants and examines factors associated with mineral metabolism controllability.

RESULTS

A total of 8,229 patients were registered from 86 facilities as the whole cohort, and 3,276 patients were randomly selected as the subcohort. The severity of SHPT was associated with a lower likelihood of achieving the targets for calcium and phosphorus, whereas patients with a history of parathyroidectomy were more likely to achieve these targets as compared with those who had not undergone surgery despite high PTH levels. The use of 2.5 mEq/l calcium dialysate was also associated with a higher likelihood of achieving the targets compared with the use of 3.0 mEq/l calcium dialysate.

CONCLUSION

The severity of SHPT and the use of dialysate with higher calcium concentration are associated with practical difficulty in managing mineral metabolism in dialysis patients. Further prospective follow-up is needed to confirm our findings and to examine their impact on patient-level outcomes.

Removal of autografted parathyroid tissue for recurrent renal hyperparathyroidism in hemodialysis patients

BACKGROUND

Recurrent renal hyperparathyroidism (HPT) is a serious problem after parathyroidectomy (PTx). We evaluated the frequency of graft-dependent recurrent HPT and the clinical outcomes after removal of the autograft.

METHODS

Between March 1980 and January 2009, 2660 patients underwent total PTx with forearm autograft. After resection of all parathyroid glands, 30 pieces of 1 x 1 x 3 mm parathyroid tissue from diffuse hyperplasia, if possible, were autografted into brachioradial muscle. Graft-dependent recurrence of HPT was diagnosed by a high PTH gradient and detection of swollen autografts by palpation and/or MRI or US.

RESULTS

In 248/2660 (9.3%) patients, removal of the graft was required a total of 327 times (53 patients required removal of the autograft several times). The cumulative frequency of graft-dependent recurrent HPT was 17.4% ten years after the initial PTx. Thirty-two patients underwent both resection of missed glands located in the neck or mediastinum and removal of the graft. En-bloc resection of autograft with surrounding muscle was required to avoid reoperation. When the intact PTH level dropped under 300 pg/ml, in the majority of patients renal HPT could be medically managed after the operation. The mean weight of the resected parathyroid tissue was 1583.7 mg. No specimen had histopathologically malignant features. Three patients suffered from hematoma in the wound.

CONCLUSIONS

Graft-dependent recurrent renal HPT is not negligible. However, in the majority of patients, renal HPT can be controlled by removal of the autograft noninvasively. Total PTx with forearm autograft is preferable for hemodialysis patients, especially when long-term survival is expected.

Cinacalcet effectively reduces parathyroid hormone secretion and gland volume regardless of pretreatment gland size in patients with secondary hyperparathyroidism

BACKGROUND AND OBJECTIVES

Cinacalcet is effective in reducing serum parathyroid hormone (PTH) in patients with secondary hyperparathyroidism. However, it has not been proven whether parathyroid gland size predicts response to therapy and whether cinacalcet is capable of inducing a reduction in parathyroid volume.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This 52-week, multicenter, open-label study enrolled hemodialysis patients with moderate to severe secondary hyperparathyroidism (intact PTH >300 pg/ml). Doses of cinacalcet were adjusted between 25 and 100 mg to achieve intact PTH <180 pg/ml. Ultrasonography was performed to measure the parathyroid gland size at baseline, week 26, and week 52. Findings were also compared with those of historical controls.

RESULTS

Of the 81 subjects enrolled, 56 had parathyroid glands smaller than 500 mm(3) (group S) and 25 had at least one enlarged gland larger than 500 mm(3) (group L). Treatment with cinacalcet effectively decreased intact PTH by 55% from baseline in group S and by 58% in group L. A slightly greater proportion of patients in group S versus group L achieved an intact PTH <180 pg/ml (46 versus 32%) and a >30% reduction from baseline (88 versus 78%), but this was not statistically significant. Cinacalcet therapy also resulted in a significant reduction in parathyroid gland volume regardless of pretreatment size, which was in sharp contrast to historical controls (n = 87) where parathyroid gland volume progressively increased with traditional therapy alone.

CONCLUSIONS

Cinacalcet effectively decreases serum PTH levels and concomitantly reduces parathyroid gland volume, even in patients with marked parathyroid hyperplasia.

Effectiveness of weekly percutaneous maxacalcitol injection therapy in patients with secondary hyperparathyroidism

Percutaneous injection therapy with vitamin D has been applied in the treatment of hyperparathyroidism (HPT); however, the application of percutaneous injection therapy with vitamin D lacks established guidelines regarding the volume of injected solution and the frequency of injection. We have developed an outpatient treatment regimen using percutaneous maxacalcitol injection therapy (PMIT) on a weekly basis for 4-6 weeks following dialysis without major complications. Intact parathyroid hormone decreased from 797 +/- 178 pg/mL to 253 +/- 25 pg/mL, and the parathyroid gland volume initially increased during the first week, but thereafter, it gradually decreased with weekly PMIT (wPMIT). Finally, the parathyroid gland volume decreased from 1.27 +/- 1.06 cm(3) to 0.24 +/- 0.15 cm(3) after wPMIT. The benefits of our method were confirmed on weekly ultrasonographic examinations, which detailed the gradual reduction in gland size following an initial increase after the first injection. Therefore, we conclude that our carefully implemented PMIT method would be an effective treatment against refractory secondary HPT.

Kidney bone disease and mortality in CKD: revisiting the role of vitamin D, calcimimetics, alkaline phosphatase, and minerals

Recent evidence suggests that the traditional syndromes known as renal osteodystrophy, secondary hyperparathyroidism, and vitamin D deficiency are related to mortality in persons with moderate to advanced chronic kidney disease (CKD). The so-called 'kidney bone disease', also known as 'mineral and bone disorders', is defined to include bone disorders, mineral disarrays, and vascular calcification. We have identified 14 common and clinically relevant conditions of contemporary nature that are related to the kidney bone disease, including calcitriol (active vitamin D) deficiency, 25(OH)-vitamin D deficiency, biochemical hyperparathyroidism, relatively low parathyroid hormone (PTH) level, increased serum alkaline phosphatase (hyperphosphatasemia), elevated fibroblast growth factor (FGF)-23, high turnover bone disease, adynamic bone disease, uremic osteoporosis, vascular calcification, hyper- and hypophosphatemia, and hyper- and hypocalcemia. We present a critical review of these 14 conditions with emphasis on patient survival and other pertinent clinical outcomes. We also review unresolved controversies surrounding the management of these conditions by administration of nutritional vitamin D (ergocalciferol and cholecalciferol), vitamin D receptor activators (calcitriol, alphacalcidiol, doxercalciferol), D-mimetics (paricalcitol, maxacalcitol), calcimimetics (cinacalcet), recombinant PTH (teriparatide), and receptor activator of nuclear factor-kappaB ligand modulators (denosumab); compare mortality predictability of PTH and alkaline phosphatase; and examine potential risks of bone disorders and mineral disarrays in CKD patients.

Associations between vascular calcification, arterial stiffness and bone mineral density in chronic hemodialysis patients

AIM

The aim of our study was to examine the associations between vascular calcification, arterial stiffness and bone mineral density (BMD) in chronic hemodialysis (HD) patients.

METHODS

The study subjects were 83 (70 men and 13 women) HD patients. All patients had computed tomography (CT) to determine aortic calcification index (ACI), pulse wave velocity (PWV) using a volume-plethysmographic apparatus, and BMD estimated by digital image processing (DIP).

RESULTS

Patients, 84.3% male, 38.6% diabetic, had a mean age of 59.3 +/- 11.2 years. In univariate linear regression analysis, ACI correlated positively with age (r = 0.586, P < 0.0001), dialysis vintage (r = 0.47, P = 0.002), pulse pressure (r = 0.311, P = 0.004), C-reactive protein (CRP) (r = 0.226, P = 0.0397) and PWV (r = 0.422, P < 0.0001). There was no significant association between ACI and serum markers of mineral metabolism. There was also a positive association between PWV and systolic blood pressure (P = 0.0004) or pulse pressure (P < 0.0001), and a trend towards greater PWV with increasing age (r = 0.494). In multivariate regression analysis only increasing age, pulse pressure, serum levels of albumin and CRP were significantly associated with ACI and PWV. Mean BMD on DIP was 2.7 +/- 0.4 mmAL. ACI was inversely correlated with BMD (r = -0.234, P = 0.0331).

CONCLUSIONS

Vascular calcification is closely associated with arterial stiffness in HD patients. BMD is inversely correlated with ACI, suggesting that measurement of hand BMD by DIP is a useful tool for assessment of renal bone disease in these patients.

Depressed expression of Klotho and FGF receptor 1 in hyperplastic parathyroid glands from uremic patients

Fibroblast growth factor 23 (FGF23) exerts its effect by binding to its cognate FGF receptor 1 (FGFR1) in the presence of its co-receptor Klotho. Parathyroid glands express both FGFR1 and Klotho, and FGF23 decreases parathyroid hormone gene expression and hormone secretion directly. In uremic patients with secondary hyperparathyroidism (SHPT), however, parathyroid hormone secretion remains elevated despite extremely high FGF23 levels. To determine the mechanism of this resistance, we measured the expression of Klotho, FGFR1, and the proliferative marker Ki67 in 7 normal and 80 hyperplastic parathyroid glands from uremic patients by immunohistochemistry. All uremic patients had severe SHPT along with markedly high FGF23 levels. Quantitative real-time reverse transcription PCR showed that the mRNA levels for Klotho and FGFR1correlated significantly with their semi-quantitative immunohistochemical intensity. Compared with normal tissue, the immunohistochemical expression of Klotho and FGFR1 decreased, but Ki67 expression increased significantly in hyperplastic parathyroid glands, particularly in glands with nodular hyperplasia. These results suggest that the depressed expression of the Klotho-FGFR1 complex in hyperplastic glands underlies the pathogenesis of SHPT and its resistance to extremely high FGF23 levels in uremic patients.

Critical issues of PTH assays in CKD

Measurement of bioactive parathyroid hormone (PTH) is essential for the optimal management of secondary hyperparathyroidism and its associated bone disorders in chronic kidney disease (CKD) patients. For this purpose, three generations of increasingly specific PTH assays have been developed over the last 4 decades. To date, however, only second-generation PTH assays are most widely used, although these have been shown to cross-react with large PTH fragments having a partially preserved N-structure, mostly PTH(7-84). The newly developed third-generation PTH assays are believed to be the most specific means of measuring PTH(1-84), but their clinical utility remains debatable. More recently, these latter assays have also been shown to react with a new N-form of PTH, which has been identified in patients with severe hyperparathyroidism and parathyroid carcinoma. Progressive research in this area has advanced our understanding considerably regarding the circulating molecular forms of PTH and their pathophysiological roles in bone abnormalities associated with CKD. However, developing an ideal PTH assay continues to be difficult because of key issues such as the reliability of PTH as a surrogate marker for bone turnover, practicality of employing third-generation PTH assays, and unknown biological implications of N-PTH and other PTH fragments. Further research exploring these issues is mandatory to understand and optimally manage parathyroid disorders and bone abnormalities in CKD patients.