Diabetes insipidus is characterized by a deficiency in which hormone?

Diabetes insipidus is primarily characterized by a deficiency in antidiuretic hormone (ADH), also known as vasopressin. ADH is produced in the hypothalamus and released from the posterior pituitary gland. Its main function is to regulate the body's retention of water by increasing the permeability of the kidney tubules, thus allowing more water to be reabsorbed back into the bloodstream.

When there is a deficiency of ADH, either due to insufficient production (as seen in central diabetes insipidus) or a lack of response in the kidneys (as seen in nephrogenic diabetes insipidus), the body cannot adequately concentrate urine. This leads to excessive urination (polyuria) and increased thirst (polydipsia) as the body attempts to compensate for the loss of water.

In contrast, the other hormones listed—prolactin, insulin, and cortisol—do not directly influence the mechanisms of water retention or regulation of urine concentration in the same manner as ADH. Prolactin is primarily involved in lactation and reproductive functions, insulin regulates glucose metabolism, and cortisol plays a role in stress responses and metabolic functions, but none of them directly affects water balance in the kidneys like ADH