[Regulation of vasopressin release in primary hypothyroidism and Addison's disease as well as in central diabetes insipidus].

The osmoregulation of arginine-8-vasopressin (AVP) was investigated in 14 patients with primary hypothyroidism, in 6 with Addison's disease, and in 21 with central diabetes insipidus (CDI). In the latter disease the effect of histamine stimulus was also evaluated. Plasma AVP was measured by radioimmunoassay (RIA). Patients with primary hypothyroidism were classified into subgroups with elevated or normal basal levels of plasma AVP. A decreased osmotic threshold was found in hypothyroid patients with augmented basal AVP levels. Patients with Addison's disease exhibited an increased basal level of plasma AVP and a decreased osmotic threshold. CDI patients according to their AVP responses on osmotic stimulus fell into two groups: CDI I gave no response at all, while CDI II responded subnormally. CDI II exhibited blunted AVP release to histamine. The AVP reactions of the CDI I patients fell into two subgroups: CDI I/A had undetectable plasma AVP, whereas histamine evoked AVP release in CDI I/B. Patients with CDI II suffer from a partial CDI, while those with CDI I/A represent a complete form of the disease and CDI I/B presumably have an osmoreceptor failure.