Diabetes insipidus, nephrogenic, recessive type

Diabetes Insipidus, Nephrogenic, Recessive Type

Diabetes insipidus, nephrogenic, recessive type is a rare genetic disorder characterized by the kidney's inability to concentrate urine, leading to excessive urination and thirst. This condition is a form of nephrogenic diabetes insipidus (NDI), which is distinct from central diabetes insipidus that involves a deficiency of the hormone vasopressin.

Pathophysiology

In nephrogenic diabetes insipidus, recessive type, the kidneys fail to respond to antidiuretic hormone (ADH), also known as vasopressin. This hormone normally acts on the kidneys to promote water reabsorption, thus concentrating the urine. In this condition, mutations in the aquaporin-2 (AQP2) gene or the vasopressin V2 receptor (AVPR2) gene lead to a lack of response to ADH, resulting in the production of large volumes of dilute urine.

Genetics

The recessive form of nephrogenic diabetes insipidus is typically associated with mutations in the AQP2 gene, which is located on chromosome 12. This gene encodes the aquaporin-2 water channel, which is essential for water reabsorption in the kidney's collecting ducts. Mutations in this gene can lead to a loss of function of the water channel, preventing the kidney from concentrating urine.

Clinical Presentation

Patients with nephrogenic diabetes insipidus, recessive type, often present in infancy or early childhood with symptoms such as:

• Polyuria (excessive urination)
• Polydipsia (excessive thirst)
• Dehydration
• Failure to thrive

These symptoms result from the body's inability to retain water, leading to dehydration and electrolyte imbalances.

Diagnosis

Diagnosis of nephrogenic diabetes insipidus involves:

• Clinical evaluation of symptoms
• Water deprivation test to assess the kidney's ability to concentrate urine
• Genetic testing to identify mutations in the AQP2 or AVPR2 genes

Management

Management of nephrogenic diabetes insipidus focuses on maintaining adequate hydration and electrolyte balance. Treatment options may include:

• Adequate fluid intake to prevent dehydration
• Low-salt and low-protein diet to reduce urine output
• Medications such as thiazide diuretics and nonsteroidal anti-inflammatory drugs (NSAIDs) to reduce urine volume

Prognosis

With appropriate management, individuals with nephrogenic diabetes insipidus, recessive type, can lead relatively normal lives. However, ongoing monitoring and treatment are necessary to prevent complications such as dehydration and electrolyte imbalances.

Also see

• Diabetes insipidus
• Nephrogenic diabetes insipidus
• Central diabetes insipidus
• Antidiuretic hormone
• Aquaporin