Vasopressin-resistant diabetes insipidus

Vasopressin-resistant diabetes insipidus (also known as nephrogenic diabetes insipidus) is a rare form of diabetes insipidus that is not responsive to the action of vasopressin, a hormone that regulates the body's water balance.

Causes

Vasopressin-resistant diabetes insipidus is usually caused by mutations in the AVPR2 gene, which provides instructions for making a protein that is involved in water balance. This protein, called the vasopressin V2 receptor, is found in the kidney where it binds to vasopressin. When the receptor is activated, it triggers a series of chemical reactions that help the kidneys reabsorb water back into the body. Mutations in the AVPR2 gene disrupt the normal function of the vasopressin V2 receptor, leading to the production of large amounts of dilute urine, a characteristic feature of diabetes insipidus.

Symptoms

The main symptom of vasopressin-resistant diabetes insipidus is excessive urination (polyuria), which can lead to dehydration. Other symptoms may include excessive thirst (polydipsia), fatigue, and weakness. In severe cases, if the condition is not properly managed, it can lead to life-threatening complications such as hypernatremia (high sodium levels in the blood) and dehydration.

Diagnosis

The diagnosis of vasopressin-resistant diabetes insipidus is based on a series of tests, including a water deprivation test, a vasopressin challenge test, and genetic testing. The water deprivation test involves withholding fluids and measuring changes in body weight, urine output, and urine concentration. The vasopressin challenge test involves administering vasopressin and measuring the response in urine concentration. Genetic testing can confirm the diagnosis by identifying mutations in the AVPR2 gene.

Treatment

The treatment of vasopressin-resistant diabetes insipidus involves managing the symptoms and preventing complications. This may include drinking sufficient fluids to match urine output, taking medications that reduce urine production, and treating the underlying cause, if known. In some cases, a diet low in salt and protein may be recommended to reduce urine output.

See also

• Diabetes insipidus
• Vasopressin
• AVPR2
• Polyuria
• Polydipsia

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