Question

Diabetes insipidus is due to
A. Hypo-secretion of pituitary hormone
B. Hyper-secretion of pituitary hormone
C. Excess of insulin
D. Deficiency of insulin

Answer 1

Hint: The term diabetes is a Greek word referring to a lot of urine production. There are two types of diabetes which are diabetes mellitus and diabetes insipidus. Diabetes insipidus varies from diabetes mellitus (Type 1 and Type 2).

Complete answer:
Diabetes insipidus occurs due to the abnormal value of the antidiuretic hormone (ADH) or because of its mutated receptor. Neurosecretory cells of the hypothalamus secrete ADH and are stored in the posterior pituitary. ADH regulates water reabsorption by increasing the water permeability in the distal convoluted tubule (DCT) and collecting duct of the nephron. The kidney responds by retaining more water which decreases urine output. If the ADH level decreases or the receptor for ADH fails to bind available ADH it causes a disease known as diabetes insipidus. Increased level of ADH causes over the hydrated condition. When blood insulin decreases blood glucose level increases this condition is insulin-dependent diabetes mellitus. Diabetes mellitus is categorized into two types i.e. Type 1 insulin-dependent diabetes mellitus and Type 2 insulin-independent diabetes mellitus.
When blood insulin increases blood glucose level decreases this condition is hypoglycemia. Treatment involves drinking sufficient water and fluids to avoid dehydration. Diabetes insipidus occurring during the time of pregnancy is known as gestational diabetes insipidus.

So, the correct answer is Option A, i.e., Hypo-secretion of the pituitary hormone.

Note: Nephron is the functional unit of the kidney. The ADH acts on two target tissues: the kidneys and smooth muscle in blood walls. Diabetes insipidus if left untreated a person may pass 30 liters of urine a day which will lead to severe dehydration and eventually coma condition. ADH is sometimes also referred to as vasopressin.