Two cases of hereditary diabetes insipidus (DI) are described, with an autopsy finding in one. The patients were brothers and 7 other relatives had symptoms of DI. The transmission of the disease in this family seemed to be an autosomal dominant trait with incomplete penetration. Both patients had the incomplete type of DI, which is diagnosed by the response of plasma AVP and the change in Uosm/Posm to 14 h water deprivation.The post-mortem examination in Case 1 showed that there was no atrophy of the supraoptic nucleus and paraventricular nucleus, but immunohistochemical studies

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 \ m=+-\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.It is well known that the elderly are susceptible to dehydration and easily develop electrolyte imba¬ lance. Various changes due to an aging process in the renal, cardiovascular, and endocrine systems have been investigated. However, little information is available concerning the effect of age on the supraoptico-neurohypophyseal system, except for data derived from experimental studies conducted mainly in rats (Friedman et al. 1956).Recently, Helderman et al. (1978) and Rowe et al. (1982) have reported an age-related increase in osmoreceptor sensitivity and an age-related failure of volume-pressure mediated vasopressin release.In this paper, we describe the response of plasma AVP to 14 h water deprivation in 30 healthy elderly individuals and young controls. Materials and MethodsTen males and 20 females were admitted to the study.Their age range was 63 to 87 years; the mean age was 76.5 years. They were carefully selected from 45 people living in a home for the aged. Those with hepatic, cardiac, and renal diseases were excluded by physcial examination and laboratory tests. None of the subjects was taking any medication. Smoking was prohibited for 12 h prior to and during the study. The nature and purpose of the study was explained to all subjects, and 14 h water deprivation was conducted from 6.00 p.m. to 8.00 a.m. on the following day. The subjects fasted during this period. Samples of venous blood were drawn for determination of AVP, osmolality, sodium, potas¬ sium, and plasma renin activity (PRA), before and after the test. Urine was collected at the same times for measurement of osmolality and electrolytes. Serum and urinary sodium and potassium were measured by a flame photometer. Model 205 Hitachi Ltd. PRA was deter¬ mined by CIS kit (France). Plasma AVP was determined by a radioimmunoassay developed in our laboratory (Sato et al. 1975). Antibodies against AVP were pro¬ duced by repeated injections for 6 months with complete Freund's adjuvant into rabbits of synthetic lysine vaso¬ pressin (Sandoz Pharmaceutical Corp.), which was coupled with bovine serum albumin by toluene diisocyanate. The antibodies obtained were highly specific for AVP showing little cross-reaction with oxytocin. The sensitivity of the assay was 0.5 µ /ml. The findings on young controls in this paper are those from a 14 h water deprivation test (Sato et al. 1976)