Antidiuretic hormone (ADH; vasopressin) is a hormone produced in the hypothalamus of the brain. It concentrates the urine by triggering the kidneys to reabsorb water into the blood stream rather than excreting water into the urine. Nephrogenic diabetes insipidus involves a defect in the kidney tubules (the portion of the kidneys that causes water to be excreted or reabsorbed). The specific kidney defect is usually a partial or complete failure of special receptors located on or within the kidney tubules to respond to ADH, the hormone that transmits the instruction to concentrate the urine to the inside of the cells. Excessive amounts of water are excreted with the urine, producing a large quantity of very dilute urine. There is little or no response to vasopressin, even though the blood level of this hormone is higher than normal. If thirst mechanisms are normal and adequate fluids are consumed, there are no significant effects on the fluid and/or electrolyte balance of the body. If inadequate fluids are consumed, the high urine output may cause dehydration and high blood sodium. Nephrogenic DI is a rare disorder. It may be present at birth as a result of a sex-linked defect (congenital nephrogenic DI) that usually affects men, although women can pass the gene on to their children. Most commonly, nephrogenic diabetes insipidus is an acquired disorder. Factors that can bring on the disorder include drugs (lithium, demeclocycline, amphotericin B), electrolyte disorders (high calcium or low potassium levels), and urinary obstruction. | 
Diabetes, Renal Disease
