Plasma cyclic AMP response to intravenous parathyroid hormone in pseudohypoparathyroidism.

Highly purified bovine parathyroid hormone (PTH) was given by intravenous bolus injection to patients being investigated for disorders of mineral metabolism, and to adult volunteer controls. Plasma cyclic AMP measured basally and at 10 min gave reliable discrimination between the normal response and cases of pseudohypoparathyroidism. Infants under 3 months of age tended to have higher basal levels of cAMP and a flatter pattern of response to the dose of PTH used. This simplified test procedure in children offers considerable advantages over previous tests of PTH responsiveness which involve urine collections and multiple blood sampling. It is suitable for selective screening of individuals suspected of pseudohypoparathyroidism on the basis of their family history or physical abnormalities.