Urinary 3',5'-cyclic adenosine monophosphate in relation to serum and urinary calcium in acromegaly and primary hyperparathyroidism.

A comparison of the interrelations between serum and urinary calcium values and the urinary excretion of cAMP in acromegaly (No. of subjects: 26), patients with primary hyperparathyroidism (n = 18) and control subjects (n = 42) is presented. The cAMP excretion was greatest in primary hyperparathyroidism, but acromegalics also exhibited higher values for this parameter than controls. A positive correlation was found between serum calcium values and cAMP in primary hyperparathyroidism, while acromegalics showed no correlation between these parameters. In controls there was a negative correlation between serum calcium and cAMP. Serum calcium levels corrected for variations in total protein concentrations were elevated both in acromegaly and primary hyperparathyroidism, mostly in the latter. Acromegalics and patients with primary hyperparathyroidism exhibited an increase in 24 h calcium excretion. While there was a negative relationship between urinary calcium excretion and cAMP in acromegaly, a positive correlation between these parameters as found in primary hyperparathyroidism. Controls showed a negative correlation between urinary calcium values and cAMP. It is concluded that the role of the parathyroids in the regulation of calcium metabolism in acromegaly is different from that of both normal controls and primary hyperparathyroidism. It is postulated that an active form of Vitamin D plays a major role in the regulation of calcium metabolism in acromegaly.