endocrine and metabolic disorders
ArginineVasopressin Deficiency (Central Diabetes Insipidus)
Diagnosis of ArginineVasopressin Deficiency
Patients with acute excessive water drinking are able to concentrate their urine during water deprivation. However, because chronic water intake diminishes medullary tonicity in the kidneys, patients with long-standing polydipsia are not able to concentrate their urine to maximal levels during water deprivation, a response similar to that of patients with partial argininevasopressin deficiency. However, unlike argininevasopressin deficiency, patients with primary polydipsia show no response to exogenous vasopressin after water deprivation. This response resembles that of argininevasopressin resistance, except that basal vasopressin levels are low compared with the elevated levels present in argininevasopressin resistance. After prolonged restriction of fluid intake to ≤ 2 L/day, normal concentrating ability returns within several weeks.