Amino terminal cleavage of PTH(1–84) to PTH(7–84) is regulated by serum calcium concentration via calcium-sensing receptor in hemodialysis patients

Background Secondary hyperparathyroidism is one of the critical complications of end-stage renal disease patients. Conventionally intact parathyroid hormone (iPTH) was used to assess secondary hyperparathyroidism, but this assay measures both PTH(1–84) (full-length parathyroid hormone) and PTH(7–84) (amino (N)-terminal-cleaved parathyroid hormone). PTH(7–84) is biologically inactive or antagonistic for PTH. In this study, we examined the relationship between serum calcium concentration and PTH(7–84)/PTH(1–84) ratio and the effect of calcimimetics on the ratio in hemodialysis (HD) patients.