Heterogeneity of carboxyl-terminal parathyroid hormone circulating forms in patients with hyperparathyroidism due to end stage renal disease.
OBJECTIVE
To study carboxyl-terminal (COOH) parathyroid hormone (PTH) circulating forms in patients with hyperparathyroidism due to end stage renal disease (ESRD).


METHODS
An immunometric assay that recognizes both intact and COOH PTH forms was developed. The assay, in conjunction with an intact assay, was used to measure PTH in serum samples obtained from 25 patients with hyperparathyroidism due to ESRD. Samples were also submitted to gel filtration chromatography in a Superdex((R)) 30 1.6 x 60 cm column, and the PTH content in the elution tubes, measured using both assays.


RESULTS
Values from 39.000 to 232.300 ng/mL (mean +/- sd = 101.680 +/- 45.330 ng/mL) were found using the COOH assay (PTH 39-84 was used as standard). Values obtained by the intact PTH assay ranged from 318 to 3.307 ng/mL (1.769 +/- 693 ng/mL) with a correlation between assays of 0.462 (p = 0.02). The elution profile obtained using the COOH assay showed a preponderance of forms with MW ranging from 8.500 to 4.500 daltons. The profiles obtained from the 25 patients were very similar.


CONCLUSIONS
In patients with hyperparathyroidism due to ESRD circulating PTH levels contain a broad range of molecular forms including COOH with MW ranging from 8.500 to 4.500 daltons. These forms are not recognized by the standard intact PTH assays. The correlation of these findings to the clinical aspects of bone disease in ESRD patients remains to be studied.
Vieira
José Gilberto H
JG
Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brasil. jose.vieira@fleury.com.br
Kunii
Ilda S
IS
Ohe
Monique N
MN
Carvalho
Aluizio B
AB
D002850:Chromatography, Gel / Q000379:methods; D015200:Fluoroimmunoassay / Q000379:methods; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000097:blood* / Q000209:etiology; D007676:Kidney Failure, Chronic / Q000150:complications*; D010281:Parathyroid Hormone / Q000097:blood / Q000737:chemistry*; D010446:Peptide Fragments / Q000097:blood / Q000737:chemistry*
D010281:Parathyroid Hormone; D010446:Peptide Fragments; C023443:carboxyl-terminal parathyroid hormone