Clinical significance of serum concentration of parathyroid hormone in patients on hemodialysis

Lee, Eun Young; Han, Byoung Geun; Chung, Choon Hee; Kim, Jin Soo; Choi, Seung Ok

Abstract

BACKGROUND
Secondary hyperparathyroidism is a common complication of chronic renal failure. The only reliable method for distinguishing patients with high turnover from those with low turnover bone disease is bone histomorphometric study, but its clinical utility is restricted. Because of its invasive nature, efforts have been made to predict indirectly the type and severity of this metabolic bone disease by serologic assays. This study was undertaken to evaluate the determinants and clinical significance of intact parathyroid hormone(iPTH) in end-stage renal disease patients on regular hemodialysis.
METHODS
Ninety-eight patients on regular hemodialysis patients were included in this study. Laboratory data included blood urea nitrogen, serum creatinine, albumin, calcium, phosphate, alkaline phosphatase and iPTH. Serum iPTH was checked by immunoradiometric assay. We also evaluated age, sex and underlying renal diseases.
RESULTS
The mean age was 50.3+/-13.8 years, duration of dialysis 42.7+/-40.1 months, duration of follow-up 38.3+/-10.9 months. Thirty patients had an iPTH level more than three times of normal (> or =195 pg/mL). Patients with iPTH level of > or =195 pg/mL had longer duration of dialysis, younger age, lower incidence of diabetes, higher serum creatinine, albumin, alkaline phosphatase, lower calcium and arterial HCO3- concentration. In patients with iPTH level of <195 pg/mL, there was significant correlation between serum iPTH and calcium level(r=-0.43, p<0.001), whereas there was no significant correlation in those with iPTH level of > or =195 pg/mL.
CONCLUSION
In patients with iPTH level of > or =195 pg/mL (three times of normal level), normal calcium-parathyroid feedback mechanism are not maintained. Serum iPTH level seems to be affected by nourishment, age, acidosis and the presence of diabetes.