Bioassay of parathyrin: Analytical characteristics and clinical performance in patients with hypercalcemia

G. G. Klee, C. M. Preissner, I. W. Schloegel, P. C. Kao

Research output: Contribution to journalArticle

11 Scopus citations

Abstract

This new bioassay for parathyrin (PTH) in plasma (bio-PTH) combines immunoextraction on affinity columns [goat anti-hPTH (1-44) conjugated to Sepharose 4B] and a receptor assay involving an osteosarcoma cell line. The mean extraction efficacy ranges from 87% (as determined with immunopurified 125I-labeled PTH) to 62% for hPTH bioactivity. The assay is standardized with synthetic hPTH (1-84) and can detect as little as 0.9 pmol/L of PTH in 2 mL of plasma. In 100 healthy adults, the 95% reference interval for bio-PTH was <0.9 to 6.1 pmol/L (median, 2.0 pmol/L) In 185 patients with surgically confirmed hyperparathyroidism, bio-PTH concentrations ranged from 1.0 to >120 pmol/L (median 12.9 pmol/L); 80% of values were >6.1 pmol/L. In 50 patients with both preoperative and postoperative determinations, the mean (± SD) concentrations of calcium in serum were 113 ± 10 and 89 ±6 mg/L, respectively; the median bio-PTH concentrations were 13.6 and 2.0 pmol/L, respectively. In 22 patients with nonparathyroid-mediated hypercalcemia, the concentration of bio-PTH ranged from <0.9 to 5.3 pmol/L (median, 1.8 pmol/L). This bio-PTH assay is slightly less sensitive than our GP235 immunoreactive PTH (iPTH) immunoassay for detecting hyperparathyroidism (Clin Chem 1982;28:69-74); however, the bioassay is more specific and detected some cases missed by the iPTH assay. Overall, 95% of the hyperparathyroid patients had an increased test result for either the bio-PTH or the iPTH assay.

Original languageEnglish (US)
Pages (from-to)482-488
Number of pages7
JournalClinical Chemistry
Volume34
Issue number3
StatePublished - 1988

ASJC Scopus subject areas

  • Clinical Biochemistry

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    Klee, G. G., Preissner, C. M., Schloegel, I. W., & Kao, P. C. (1988). Bioassay of parathyrin: Analytical characteristics and clinical performance in patients with hypercalcemia. Clinical Chemistry, 34(3), 482-488.