Water deprivation test

Baseline laboratory blood and urine samples were obtained (Table 1), and water deprivation test followed by the administration of AVP was carried out under constant medical supervision. Free fluid intake was allowed until 1 h before the test began. If the sodium level rose above 150 mmol/L or weight loss increased above 5% of their weight to time = 0, desmopressin was administered. During the test, their well‐being was monitored continuously and blood pressure, pulse, weight, and urinary output were measured hourly and plasma sodium analyzed immediately after sampling. Plasma AVP concentration was measured three times during the test.

Clinical characteristics of the probands