Highly sensitive two-site immunoradiometric assay of parathyrin, and its clinical utility in evaluating patients with hypercalcemia.

Abstract

We have developed a highly sensitive, two-site immunoradiometric assay (IRMA) for human parathyrin (PTH) that is specific for the intact, secreted, biologically active 84-amino-acid peptide. This assay has several technical advantages: it does not detect even high concentrations of inactive carboxyl-terminal fragments, results are available within 24 h, and the detection limit for intact hormone is low (1 ng/L). The assay readily measures concentrations of PTH in all healthy subjects and distinguishes these values from low or undetectable PTH values observed in clinical situations in which PTH secretion is expected to be suppressed. We found complete separation of results from 37 patients with surgically proven hyperparathyroidism and those from 23 patients with hypercalcemia associated with malignancy, the latter having PTH values at or below the lower limits of normal for this assay. The sensitivity, specificity, and rapid turnaround time of this two-site IRMA should advance the laboratory evaluation of patients with disorders of calcium metabolism.

Cica‐clamp technique: a method for quantifying parathyroid hormone secretion: a sequential citrate and calcium clamp study

“…Only when both antibodies were bound to the sanzepeptide a signal was traced, i.e. PTH was measured [8]. S-albumin, S-protein, S-creatinine, S-Na' and S-Kt were analysed on a SMAC IIautoanalyser (Technicon, Tarrytown, NY, USA).…”

The management of primary hyperparathyroidism

“…The precise concentration of PTH defining parathyroid and nonparathyroid causes of hypercalcaemia will vary depending on the assay chosen and approximates to a value in the middle of the reference range. While 90% of patients with HPT will have an elevated PTH concentration (Nussbaum et al ., 1987;Endres et al ., 1991), it should be noted that the majority of commercial assays in use today measure intact hormone [PTH(1-84)] and PTH(7-84) fragment, with the result that a value in the upper half of the reference range is inappropriate in the presence of an elevated calcium level and is highly suggestive of primary hyperparathyroidism (Lepage et al ., 1998;Gao et al ., 2001) [Evidence B]. The major causes of hypercalcaemia (defined as a calcium adjusted for albumin > 2·65 mmol/l on at least two occasions) are given in Table 1.…”

Classification of dynamical diseases by new mathematical tools: Application of multi‐dimensional phase space analyses to the pulsatile secretion of parathyroid hormone

“…Half the results were obtained with the Allegro intact PTH immunoradiometric assay system (Nichols, San Juan, Capistrano, CA, USA) which was used according to the manufacturers' specifications [22]. This assay comprises affinity-purified polyclonal antisera against human PTH-(39-84) coated in excess to a bead, a polyclonal affinity-purified anti-PTH-( 1-34) antibody radioiodinated with lZsI (tracer), and synthetic human PTH-( 1-84) standards.…”