Radioimmunoassay of Serum Parathyroid Hormone in Postmenopausal Osteoporosis

Radioimmunoassay of parathyroid hormone (PTH) in human serum was carried out using guinea pig antibody against bovine parathyroid hormone and 125I labeled highly purified bovine PTH employing dextran-coated charcoal to separate the bound and free fraction. With the use of this method, PTH was detected in the serum of about 85% of 118 normal male and female subjects of various ages. PTH in serum was definitely elevated in primary and secondary hyperparathyroidism and pseudohypoparathyroidism but was undetectable or low in idiopathic and postoperative hypoparathyroidism. In 11 patients with postmenopausal osteoporosis with compression fracture, serum PTH was significantly higher than in age-matched controls. Serum PTH increased along with the progress in the severity of vertebral bone change in X-ray picture.