Urinary adenosine 3',5'-monophosphate (cAMP) response to antidiuretic hormone in diabetes insipidus (DI): comparison between congenital nephrogenic DI type 1 and 2, and vasopressin sensitive DI.

Urinary adenosine 3',5'-monophosphate (cAMP) excretion before and after administration of aqueous vasopressin (pitressin) and 1-deamino-8-D-arginine vasopressin (DDAVP) was measured in congenital nephrogenic and in vasopressin sensitive diabetes insipidus (VS-DI). Excretion of cAMP into the urine increased markedly in response to pitressin (676%) and to DDAVP (252%) in VS-DI. Nephrogenic diabetes insipidus (N-DI) could be divided into two categories (type 1 and type 2) in respect to urinary cAMP responsiveness. In type 1, cAMP excretion showed no definite change after stimulation with pitressin (102%) or DDAVP (127%). On the other hand, urinary excretion of cAMP was significantly elevated in response to DDAVP in familial cases of N-DI type 2 (1269%) without producing any concentrating effect on the urine. Two different defects are considered to be involved in the pathogenesis of N-DI.