Pseudohypoparathyroidism: defective excretion of 3',5'-AMP in response to parathyroid hormone.
Urinary excretion of cyclic adenosine 3',5'-monophosphate (3',5'-AMP) was tested in normal subjects and patients with pseudohypoparathyroidism, idiopathic hypoparathyroidism, surgical hypoparathyroidism, and pseudopseudohypoparathyroidism under basal conditions and after a 15 min infusion of purified parathyroid hormone. Basal excretion of the nucleotide was less than normal in the patients with hypocalcemic disorders and greater than normal in pseudopseudohypoparathyroidism. Parathyroid hormone caused a marked increase in excretion of 3',5'-AMP in all subjects except those with pseudohypoparathyroidism; nine patients with this disorder did not respond to the hormone and four showed a markedly deficient response. Radioimmunoassay showed that parathyroid hormone circulated in increased amounts in plasma from patients with pseudohypoparathyroidism and became undetectable when serum calcium was increased above 12 mg/100 ml. Suppression of parathyroid hormone secretion by induction of hypercalcemia did not alter the deficient response to exogenous hormone. The results indicate that: (a) parathyroid hormone circulates in abnormally high concentrations in pseudohypoparathyroidism and secretion of the hormone responds normally to physiological control by calcium; (b) testing urinary excretion of 3',5'-AMP in response to infusion of purified parathyroid hormone appears to be an accurate and sensitive index for establishing the diagnosis of pseudohypoparathyroidism; and (c) the metabolic defect of the disorder can be accounted for by a lack of or defective form of parathyroid hormone-sensitive adenyl cyclase in bone and kidney.
D000227:Adenine Nucleotides / Q000652:urine*; D000262:Adenylyl Cyclases / Q000378:metabolism; D001842:Bone and Bones / Q000201:enzymology; D002118:Calcium / Q000097:blood; D000242:Cyclic AMP / Q000652:urine; D007668:Kidney / Q000201:enzymology; D010281:Parathyroid Hormone; D011547:Pseudohypoparathyroidism / Q000175:diagnosis / Q000378:metabolism; D011863:Radioimmunoassay
D000227:Adenine Nucleotides; D010281:Parathyroid Hormone; D000242:Cyclic AMP; D000262:Adenylyl Cyclases; D002118:Calcium