Diabetes insipidus a disease in which the secretion of or response to the pituitary hormone vasopressin is impaired, resulting in the production of very large quantities of dilute urine, often with dehydration and insatiable thirst. defect in the hypothalamus (thirst center) could be the most probable cause of primary DI. Meningitis or a brain tumor could interfere with the synthesis, transport, or release of antidiuretic hormone (ADH) and cause central DI. Lithium therapy affects the renal response to ADH and results in nephrogenic DI, or drug-related DI.