ParathyroidHormone Assay inPrimaryHyperparathyroidism: Experiences witha RadioimmunoassayBased on

A radioimmunoassay is described for parathyroid hormone in human serum, in which commercially available reagents are used almost exclusively. This assay can be done by any laboratory with experience in radloimmunoassay. Thirty-two of thirty-three pa-tients with surgically proven primary hyperparathy-roidism had detectable concentrations of parathyroid hormone in their serum, and concentrations of the hormone exceeded the normal range in 24 of them. Significant positive correlations were found between pre-operative serum calcium, pre-operative serum parathyroid hormone, and the weight of parathyroid tissue removed at operation. These three parameters were also significantly correlated with severity of the skeletal changes as assessed by semiquantitative histological methods. Additional Keyphrases: indexes to hyperparathyroidism #{149}diagnostic aid #{149}calculous disease #{149}parathy-roid adenoma e normal values Several variables are used to assess the severity of primary hyperparathyroidism: serum calcium (1, 2), serum immunoreactive parathyroid hormone (3, 4), quantitation of skeletal lesions (5, 6), measurement of urinary excretion of cyclic AMP (7), and estima-tion of plasma ionic calcium (8). We recently corre-lated the first three of these with one another and with the weight of abnormal parathyroid tissue re-moved from 33 patients at operation or autopsy. Our results are reported in this paper, and the value of pre-operative parathyroid hormone (PTH) assay and skeletal biopsy is assessed. Patients and Methods Primary hyperparathyroidism was diagnosed in 33 patients by criteria previously outlined (9). Patients were included only if their pre-operative serum calci-um was at least 10.8 mg/dl, if their serum creatinine was 3.0 mg or less per deciliter, and if at least 121 mg of parathyroid tissue were removed surgically o