Critical Governance Issue of Parathyroid Hormone Assays and its Selection in the Management of Chronic Kidney Disease Mineral and Bone Disorders

Agreement of Parathyroid Hormone Status Measured by Intact and Biointact Parathyroid Hormone Assays among Chronic Kidney Disease Patients and Its Correlation with Bone Turnover Parameters

Background

This study aimed to determine the agreement between intact parathyroid hormone (iPTH) and biointact parathyroid hormone (bio-PTH) assays and to correlate them with bone markers.

Methods

This cross-sectional study included 180 patients with chronic kidney disease (CKD) stages 3b, 4 and 5D. We measured their iPTH, bio-PTH, 25-hydroxyvitaminD (25(OH)D), C-terminal telopeptide collagen (CTX), procollagen 1 intact N-terminal propeptide (P1NP), calcium, phosphate and alkaline phosphatase (ALP).

Results

Higher iPTH than bio-PTH concentrations were seen in CKD stages 3b, 4 and 5D (58[62] versus 55[67] pg/mL, 94[85] versus 85[76] pg/mL and 378[481] versus 252[280] pg/mL, respectively). Both PTH assays showed good agreement among all the subjects, with an intraclass correlation coefficient of 0.832 (P-value < 0.001). The Passing-Bablok showed that the equation for the bio-PTH was PTH = 0.64 iPTH + 15.80, with r = 0.99. The Bland-Altman plots showed increased bias with an increasing PTH concentration. Both PTH assays showed a high positive correlation with CTX and P1NP, a moderate correlation with phosphate, a low correlation with ALP and calcium, and a negligible correlation with phosphate and 25(OH)D.

Conclusion

The iPTH and bio-PTH assays were in agreement, but their bias increased with the PTH concentration. The unacceptable large bias indicates that the two assays cannot be used interchangeably. They had a variable correlation with the bone parameters.

Impact of adherence to CKD-MBD guidelines on mortality among Japanese dialysis patients: an ecological study

INTRODUCTION

This study evaluated the association between prefecture-level achievement of chronic kidney disease-mineral and bone disorder (CKD-MBD) parameter targets and mortality in Japanese dialysis patients.

MATERIALS AND METHODS

We conducted an ecological study of all prefectures in Japan using data from the Japanese Society of Dialysis Therapy and National Vital Statistics between 2016 and 2017. We calculated adherence rates to recommend target ranges for CKD-MBD parameters, including phosphate, corrected calcium, and parathyroid hormone (PTH), and explored associations of these rates with prefecture-specific standardized mortality rates (SMRs) among the general population and among prevalent dialysis patients using bivariate association analysis and structural equation modeling.

RESULTS

Prefecture-level adherence to the target phosphate range was significantly and negatively associated with prefecture-specific SMRs in men (standardized estimate (β) = - 0.61, p < 0.001) and women (β = - 0.41, p < 0.001). However, prefecture-level adherence to the target corrected calcium range was significantly and negatively associated with prefecture-specific SMRs only in men (β = - 0.28, p = 0.01). Meanwhile, prefecture-level adherence to the target PTH range was significantly and positively associated with prefecture-specific SMRs in men (β = 0.23, p = 0.04). Prefecture-level SMRs of females in the general population had a significant impact on prefecture-level SMRs of female dialysis patients (β = 0.27, p = 0.03). The models explained 52% of variance in SMR for men and 33% for women.

CONCLUSION

A higher prefecture-level achievement rate of the target phosphate range recommended by the Japanese CKD-MBD guidelines was associated with a lower prefecture-specific SMR in the Japanese dialysis population.

The Correlation between Estimated Glomerular Filtration Rate and Parathyroid Hormone Levels in Predialysis-chronic Kidney Disease Adult Patients at Sanglah General Hospital, Bali, Indonesia

BACKGROUND: Chronic kidney disease (CKD) is a structural or functional kidney disease for more than 3 months. In predialysis CKD patients, the serum parathyroid hormone levels increase progressively since the early stages of the disease to maintain phosphate homeostasis. Glomerular filtration rate (GFR) has been widely accepted to assess renal function. The GFR assessment is used to determine the CKD stadium. AIM: This study aims to analyze the correlation between GFR and parathyroid hormone levels in predialysis CKD patients undergoing treatment at Sanglah General Hospital Denpasar. METHODS: A cross-sectional observational study was conducted among predialysis CKD patients undergoing treatment at Sanglah General Hospital Denpasar who met the inclusion and exclusion criteria. The inclusion criteria were adult patients (≥18 years) who were accepting to participate in the study. Exclusion criteria were patients with predialysis CKD after thyroidectomy and/or parathyroidectomy and liver disease. The parathyroid hormone levels, blood urea nitrogen, creatinine, and GFR were examined and analyzed by SPSS version 17 for Windows. RESULTS: A total of 77 patients with predialysis CKD in this study obtained a median of e-GFR of 21.09 (4.72–75.80) mL/min/1.73 m2. The median level of parathyroid hormone was 82.07 pg/mL (15.83–716.60 pg/mL). Spearman’s correlation analysis results obtained a strong and significant negative correlation between the e-GFR value and parathyroid hormone levels (r = −0.540; p = 0.000). CONCLUSION: The parathyroid hormone levels assessment could be used as a recommendation in evaluating the CKD progressivity among predialysis adult patients at Sanglah General Hospital, Bali, Indonesia, due to the strong significant correlation.

Serum sirtuin 1 is independently associated with intact PTH among patients with chronic kidney disease

Background

Sirtuin 1 is involved in the pathogenesis of age-related diseases.

Purpose

The aim of the study was to assess the clinical and diagnostic value of serum sirtuin 1 concentration in patients with CKD.

Patients and Methods

The serum sirtuin 1 level was evaluated using ELISA kit in 100 CKD patients stratified for five stages and in a control group of 24 healthy volunteers.

Results

Serum sirtuin 1 concentration was higher in the CKD group compared with the control group (p<0.05). Sirtuin 1 correlated with conventional CKD biomarkers and eGFR equations, intact parathyroid hormone (iPTH) and age (all p<0.05). Statins, AT₁ receptor antagonists and β-blockers use were associated with decreased sirtuin concentration (p<0.05). Sirtuin 1 was able to distinguish CKD from control group with high sensitivity and specificity (93% and 87%, respectively; AUC=0.954). Surprisingly, after adjustment only iPTH concentration was an independent predictor of sirtuin 1 level.

Conclusion

The association between sirtuin 1, eGFR equations and iPTH indicates its possible usefulness as a kidney function marker. In terms of iPTH being the only independent predictor of circulating sirtuin 1 it can be considered as an indirect cardiovascular risk biomarker regardless of renal function and provide additional information for patient management. Alternatively, sirtuin 1 is recognized as protective against vascular disease, and we demonstrated a positive correlation with iPTH, which may be related to accumulation of (7-84)-PTH having opposite biological effects to full-length PTH. Further studies are needed to explore the interplay between sirtuin 1, PTH and CKD-related vascular calcification as well as to assess its prognostic value in observational studies.

The path to the standardization of PTH: Is this a realistic possibility? a position paper of the IFCC C-BM

Parathyroid hormone (PTH) determination is of greatest importance for patients suffering from parathyroid gland disorders and for the follow-up of bone turnover in patients suffering from chronic kidney disease (CKD). Two generations of PTH assays are simultaneously present on the market for PTH quantification. As these assays are not yet standardized, this results in a significant level of confusion in the care of CKD patients. One key objective of the IFCC Committee for Bone Metabolism is to improve this situation. In this position paper, we will highlight the current state of PTH testing and propose a pathway to ultimately overcome issues resulting from PTH assay variability.

Comparison of Second- and Third-Generation Parathyroid Hormone Test Results in Patients with Chronic Kidney Disease

BACKGROUND In patients with chronic kidney disease (CKD), secondary hyperparathyroidism is assessed by measuring serum parathyroid hormone (PTH) levels. Well-established, recommended, second-generation intact parathyroid hormone (iPTH) tests are typical; rarely are more recent third-generation PTH 1-84 assays used. The agreement between results of the 2 tests in patients with CKD has not been sufficiently defined. MATERIAL AND METHODS This study aimed to compare Roche second- and third-generation PTH assays by establishing a quantitative relationship between the results of assays in patients with CKD and assessing degree of their correlation with kidney function and calcium-phosphate and bone metabolism parameters. In 205 patients with stages 3 to 5D CKD and 30 healthy controls, we measured levels of iPTH and PTH (1-84), creatinine, urea, cystatin C, calcium, inorganic phosphate, magnesium, alkaline phosphatase, bone alkaline phosphatase, osteocalcin, and ß-CrossLaps. RESULTS The third-generation PTH assay results were more than 40% lower than those obtained with the second-generation test in patients undergoing dialysis and approximately 30% lower in patients in the pre-dialysis period. PTH concentrations determined with both assays were almost to the same extent correlated with calcium-phosphate and bone metabolism parameters, and renal function indices. Formulas have been developed enabling 2-way conversion of PTH results determined with both the second- and third-generation PTH assays: For dialyzed patients, PTH (1-84)=0.5181iPTH+18.0595. Serum osteocalcin, ß-CrossLaps, and total calcium were independent predictors of PTH levels. CONCLUSIONS Correcting for the established quantitative differences, the second-and third-generation PTH tests can be used interchangeably, given the almost identical pathophysiological correlations of their results with calcium-phosphate and bone metabolism parameters.

Rapid electrochemical device for single-drop point-of-use screening of parathyroid hormone

Aim: Novel electrochemical point-of-use biosensing device for rapid assessment of parathyroid hormone (PTH) levels has been developed. Materials & methods: The analytical nanobiosensor was designed by integrating unique high density semiconducting nanostructured arrays on a flexible sensing surface. Surface modification technique was tailored for enhancing the interaction of nanostructure–biological interface to capture the target PTH level. Results & conclusion: We demonstrate a rapid nanobiosensor to detect PTH in human serum, plasma and whole blood with a limit of detection of 1 pg/ml and a clinically relevant dynamic range from 1 to 1000 pg/ml. This is the first demonstration of detecting PTH as a point-of-use device devoid of sample pretreatment suitable in a surgical setting with high specificity to PTH.

Secondary Hyperparathyroidism: Pathogenesis and Latest Treatment

The classic pathogenesis of secondary hyperparathyroidism (SHPT) began with the trade-off hypothesis based on parathyroid hormone hypersecretion brought about by renal failure resulting from a physiological response to correct metabolic disorder of calcium, phosphorus, and vitamin D. In dialysis patients with failed renal function, physiological mineral balance control by parathyroid hormone through the kidney fails and hyperparathyroidism progresses. In this process, many significant genetic findings have been established. Abnormalities of Ca-sensing receptor and vitamin D receptor are associated with the pathogenesis of SHPT, and fibroblast growth factor 23 has also been shown to be involved in the pathogenesis. Vitamin D receptor activators (VDRAs) are widely used for treatment of SHPT. However, VDRAs have calcemic and phosphatemic effects that limit their use to a subset of patients, and calcimimetics have been developed as alternative drugs for SHPT. Hyperphosphatemia also affects progression of SHPT, and control of hyperphosphatemia is, therefore, thought to be fundamental for control of SHPT. Currently, a combination of a VDRA and a calcimimetic is recognized as the optimal strategy for SHPT, and for other outcomes such as reduced cardiovascular disease and improved survival. The latest findings on the pathogenesis and treatment of SHPT are summarized in this review.

Parathyroid Hormone Fragments: New Targets for the Diagnosis and Treatment of Chronic Kidney Disease-Mineral and Bone Disorder

As a common disorder, chronic kidney disease (CKD) poses a great threat to human health. Chronic kidney disease-mineral and bone disorder (CKD-MBD) is a complication of CKD characterized by disturbances in the levels of calcium, phosphorus, parathyroid hormone (PTH), and vitamin D; abnormal bone formation affecting the mineralization and linear growth of bone; and vascular and soft tissue calcification. PTH reflects the function of the parathyroid gland and also takes part in the metabolism of minerals. The accurate measurement of PTH plays a vital role in the clinical diagnosis, treatment, and prognosis of patients with secondary hyperparathyroidism (SHPT). Previous studies have shown that there are different fragments of PTH in the body's circulation, causing antagonistic effects on bone and the kidney. Here we review the metabolism of PTH fragments; the progress being made in PTH measurement assays; the effects of PTH fragments on bone, kidney, and the cardiovascular system in CKD; and the predictive value of PTH measurement in assessing the effectiveness of parathyroidectomy (PTX). We hope that this review will help to clarify the value of accurate PTH measurements in CKD-MBD and promote the further development of multidisciplinary diagnosis and treatment.