The response of plasma arginine vasopressin to 14 h water deprivation in the elderly.

The response of plasma arginine vasopressin (AVP) to 14 h water deprivation was investigated in 30 healthy elderly individuals ranging in age from 63 to 87 years, with a mean age of 76.5 years. The mean AVP concentrations, both at normal hydration and after the water deprivation test, were significantly lower than those in the young. Moreover, the post-test mean value of Uosm/Posm in the elderly increased up to 1.55 +/- 0.52, which is lower than that in the young in whom the value was greater than 2. These results suggest that the aged are prone to incomplete diabetes insipidus. This pathological state might predispose to electrolyte imbalance in the elderly.