Intravenous vitamin D therapy reduces PTH-(1-84)/large C fragments ratio in chronic hemodialysis patients.
BACKGROUND
Renal osteodystrophy is one of the major complications in patients with chronic renal failure. Large C-PTH fragments are secreted from the parathyroid glands and exert antagonistic actions against PTH-(1-84). The PTH-(1-84)/large C-PTH fragments ratio reflects both biosynthesis and processing of PTH; however the alteration of the ratio under vitamin D therapy has not been investigated.


METHODS
Seventeen hemodialysis patients with intact PTH levels of >300 pg/ml were enrolled. Calcitriol or maxacalcitol were administered intravenously for 78 weeks. Intact PTH, PTH-(1-84), and the PTH-(1-84)/large C-PTH fragments ratio were measured at 0, 13, 26, 52 and 78 weeks.


RESULTS
Intact PTH and PTH-(1-84) levels, which were 492.0 +/- 115.7 and 303.4 +/- 105.4 pg/ml, respectively, at baseline, significantly decreased at the end of the study to 268.9 +/- 121.9 (p < 0.0001) and 190.7 +/- 106.9 pg/ml (p = 0.0008), respectively. In contrast, large C-PTH fragments, which were 152.7 +/- 53.5 pg/ml at baseline, did not significantly change at 78 weeks (144.5 +/- 72.2 pg/ml, p = 0.7612). Consequently, the PTH-(1-84)/large C-PTH fragments ratio was significantly reduced from 2.25 +/- 1.31 to 1.47 +/- 0.89 (p = 0.0004).


CONCLUSIONS
The PTH-(1-84)/large C-PTH fragments ratio reflects the change of PTH biosynthesis, processing and secretion from the parathyroid glands, and it may be a beneficial marker to evaluate the overall biological PTH action and predict bone turnover status in hemodialysis patients under intravenous vitamin D therapy.
Kihara
Takashi
T
Department of Medicine and Clinical Science, Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan. takashi_net@hotmail.com
Ichikawa
Haruo
H
Morimoto
Hisanori
H
Yano
Ai
A
Akagi
Shigeru
S
Nakao
Kazushi
K
Kohmoto
Hiroko
H
Wada
Jun
J
Kumagai
Isao
I
Makino
Hirofumi
H
D000135:Acid Phosphatase / Q000097:blood; D000469:Alkaline Phosphatase / Q000097:blood; D050071:Bone Density Conservation Agents / Q000008:administration & dosage*; D016723:Bone Remodeling / Q000187:drug effects; D002117:Calcitriol / Q000008:administration & dosage* / Q000031:analogs & derivatives; D002118:Calcium / Q000097:blood; D012080:Chronic Kidney Disease-Mineral and Bone Disorder / Q000097:blood / Q000188:drug therapy; D005260:Female; D006801:Humans; D007275:Injections, Intravenous; D007527:Isoenzymes / Q000097:blood; D008297:Male; D008875:Middle Aged; D015675:Osteocalcin / Q000097:blood; D010281:Parathyroid Hormone / Q000031:analogs & derivatives* / Q000097:blood; D010446:Peptide Fragments / Q000097:blood; D010758:Phosphorus / Q000097:blood; D006435:Renal Dialysis; D000071681:Tartrate-Resistant Acid Phosphatase; D014815:Vitamins / Q000008:administration & dosage*
D050071:Bone Density Conservation Agents; D007527:Isoenzymes; C470125:PTH protein, human; D010281:Parathyroid Hormone; D010446:Peptide Fragments; D014815:Vitamins; D015675:Osteocalcin; D010758:Phosphorus; D000469:Alkaline Phosphatase; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase; D002117:Calcitriol; C051883:maxacalcitol; D002118:Calcium