[A case of congenital nephrogenic diabetes insipidus accompanied by hypertension]

Congenital nephrogenic diabetes insipidus is a rare disorder in which the kidney is insensitive to the antidiuretic hormone, vasopressin. In most cases, a mutation in the vasopressin type 2(V2) receptor gene is the genetic cause of the disease. So far, few cases of congenital nephrogenic diabetes insipidus with hypertension have been reported. We report one male case of congenital nephrogenic diabetes insipidus accompanied by hypertension. The patient was a 24-year-old man who had suffered from polyuria and polydipsia since infancy and had been found to have hypertension at about 16 years. He was admitted to hospital in May 2000 for investigation of polyuria and hypertension with a high plasma level of renin activity of 10.4 ng/ml/hr. On physical examination, the blood pressure was 150/90 mmHg and the daily urinary output was 18.5 l. There was no change in urine volume and urine osmolality after an intramascular injection of vasopressin and water deprivation. The blood pressure and plasma renin activity were increased from 127/73 mmHg to 146/87 mmHg and from 4.9 ng/ml/hr to 6.1 ng/ml/hr, respectively, by a 4-hour dehydration test. He was found to have a C-to-T transition at nucleotide position 675 by sequencing analysis of the V2 receptor gene. After administration of hydrochlorothiazide, both the blood pressure and urine volume were reduced. Consequently, it was suggested that activation of the renin-angiotensin system by dehydration, at least in part, contributed to high blood pressure in this case.