Mechanisms of diabetes insipidus

Diabetes insipidus (DI) is part of a group of hereditary or acquired polyuria and polydipsia diseases. It is a rare disease that causes frequent urination. The large volume of urine is diluted, mostly water. To make up for lost water, a person with DI may feel the need to drink large amounts and is likely to urinate frequently, even at night, which can disrupt sleep and, on occa­sion, cause bedwetting.

Two very different mechanisms can cause diabetes insipidus:
• Inadequate release of antidiuretic hormone (ADH, also called arginine vasopressin or AVP) from the hypothalamus (central diabetes insipidus) and
• Inadequate response of the kidney to ADH (nephrogenic diabetes insipidus).

DI can occur at any age, but is mostly found in adults. The disease affecting only about 1 in 25,000 people.

DI should not be confused with diabetes mellitus (DM), which results from insulin deficiency or resistance leading to high blood glucose, also called blood sugar. DI and DM are unrelated, although they can have similar signs and symptoms, like exces­sive thirst and excessive urination. DI can be caused by two fundamentally different defects: Inadequate/impaired secretion of AVP from the posterior pituitary gland and impaired/insufficient renal response to ADH. AVP, a neurohypophyseal nonapeptide, regulates body water and osmotic homeostasis.

DM is far more common than DI and receives more news coverage. DM has two main forms, type 1 diabetes and type 2 diabetes.

Arginine vasopressin (AVP) is an antidiuretic hormone (ADH) is a hormone released from the rear most part of the pituitary gland (the posterior pituitary). This gland is located at the base of the brain, and is about 3 to 5 centimeters behind the bridge of the nose. The AVP system maintains water balance based on serum osmolality and arterial blood volume via the vasopressin-2-receptor. AVP circulates in the bloodstream and acts on the kidneys to reduce the amount of water that is passed out in urine.
Mechanisms of diabetes insipidus