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- Title
Amino terminal cleavage of PTH(1–84) to PTH(7–84) is regulated by serum calcium concentration via calcium-sensing receptor in hemodialysis patients.
- Authors
Koshikawa, Masao; Nishiguchi, Kensuke; Yorifuji, Soshi; Shimazu, Keiji; Takaori, Koji; Mori, Keita; Eguchi, Eriko; Okada, Kikuo; Tanaka, Atsuo; Kuwahara, Takashi
- Abstract
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. Ionized-calcium (iCa), iPTH, and whole PTH (wPTH) were measured at the start of HD sessions on HD patients. Patients were divided into four groups by presence (+) or absence (−) of vitamin D (VD) and calcimimetics (CM). PTH(7–84)/PTH(1–84) ratios of the four groups [VD(−)CM(−), VD(+)CM(−), VD(−)CM(+) and VD(+)CM(+)] were 0.735, 0.799, 0.844, and 1.156, respectively. In VD(−)CM(−) and VD(+)CM(−) groups, iCa and PTH(7–84)/PTH(1–84) ratio showed equilateral correlation ( r = 0.634, p < 0.001 and r = 0.360, p < 0.01, respectively). In calcimimetics-treated group, iCa and PTH(7–84)/PTH(1–84) ratio did not show correlation. Whereas in the absence of calcimimetics cleavage of N-terminal PTH was regulated by serum calcium concentration, this regulation was abolished in the presence of calcimimetics. This suggests that cleavage of N-terminal PTH is regulated by calcium concentration via a calcium-sensing receptor and that calcimimetics may have a novel effect to reduce PTH level.
- Subjects
HYPERPARATHYROIDISM; KIDNEY diseases; PARATHYROID hormone; HEMODIALYSIS; VITAMIN D; PATIENTS
- Publication
Clinical & Experimental Nephrology, 2010, Vol 14, Issue 3, p233
- ISSN
1342-1751
- Publication type
Article
- DOI
10.1007/s10157-010-0264-5