Circulating 1-84 PTH and large C-terminal PTH fragment levels in uremia.
BACKGROUND
The so-called "intact parathyroid hormone (iPTH)" assay detects large C-terminal PTH fragments that are lacking several N-terminal amino acid residues in addition to 1-84 PTH molecules.


METHODS
Blood samples were obtained from 65 predialysis patients (male, 35; female, 30) and 109 dialysis patients (male, 73; female, 36). The plasma 1-84 PTH levels were determined by a specific immunoradiometric assay (IRMA).


RESULTS
The ratio of 1-84 PTH/iPTH did not show a significant correlation with glomerular filtration rate (GFR) among patients with a GFR of more than 80 ml/min, while it showed a positive correlation with GFR among patients with a GFR of less than 80 ml/min. The ratio of 1-84 PTH/iPTH demonstrated a significant tendency to decrease in the order of patients with normal renal function (0.928 +/- 0.182), those with renal dysfunction (0.836 +/- 0.186; P < 0.05 vs patients with GFR > 80 ml/min [i.e., normal renal function]), and those with maintenance hemodialysis (0.618 +/- 0.123; P < 0.01 vs patients with GFR > 80 ml/min). The plasma levels of 1-84 PTH and conventional iPTH showed a close correlation in dialysis patients. Neither 1-84 PTH levels nor secondary parameters calculated from them showed a better correlation with bone metabolic markers than iPTH levels.


CONCLUSIONS
Circulating large C-terminal PTH fragment levels are increased in uremic patients. However, this noninvasive study failed to demonstrate the superiority of the specific 1-84 assay compared with the conventional iPTH assay to evaluate bone metabolism.
Division of Clinical Nephrology and Intensive Care Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan. jjkaz@med.niigata-u.ac.jp
Junichiro James
JJ
Kazama
Tsukasa
T
Omori
Isei
I
Ei
Kyoko
K
Ei
Mizue
M
Oda
Hiroki
H
Maruyama
Ichiei
I
Narita
Fumitake
F
Gejyo
Takashi
T
Shigematsu
Masafumi
M
Fukagawa
D000328:Adult; D000368:Aged; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D015675:Osteocalcin / Q000097:blood; D010281:Parathyroid Hormone / Q000097:blood*; D010446:Peptide Fragments / Q000378:metabolism*; D011869:Radioligand Assay; D006435:Renal Dialysis; D013223:Statistics as Topic; D014511:Uremia / Q000097:blood*
D010281:Parathyroid Hormone; D010446:Peptide Fragments; D015675:Osteocalcin