Diabetes Insipidus

Some signs and symptoms associated with diabetes insipidus are:

• Feeling extremely thirsty very often
• Frequent urination, often requiring waking up through the night.
• Producing large amounts of pale urine
• Preference for cold liquids over warm liquids
• If not treated or unable to have enough water, it can cause dehydration

Infants with diabetes insipidus may present the following symptoms:

• Heavy, wet diapers
• Bed-wetting
• Trouble sleeping
• Constipation
• Delayed growth
• Fever
• Vomiting
• Weight loss

In diabetes insipidus, the body fails to balance the levels of body fluids. When kidneys filter blood, most of the fluid is reabsorbed back into the bloodstream while the waste is eliminated along with small quantities of fluid, which forms the urine.

Antidiuretic hormone, or vasopressin, is responsible for the reabsorption of the fluid. However, when the hypothalamus or pituitary gland (parts of the brain that control the release of ADH) fail to function well, levels of ADH decline. As a result, the formation of urine becomes abnormally high. Types of diabetes insipidus and the causes of each are as follows:

• Central Diabetes Insipidus: This type develops when the central nervous system-related organs are affected. When damage occurs to the pituitary gland or hypothalamus from a tumour, surgery, injury or ailment can contribute to developing central diabetes insipidus. Levels and functions of ADH are adversely affected, including its production, storage, and release. It may also be associated with inherited genetic conditions.

• Nephrogenic Diabetes Insipidus: This type occurs when the structures of the kidneys that respond to ADH fail to function. The defect may be present in inherited disorders or chronic renal disorders. Certain drugs like lithium or antiviral medications can also cause this disorder.

• Gestational Diabetes Insipidus: This condition is rare and occurs only during pregnancy. An enzyme made by the placenta during pregnancy plays a role in eliminating ADH in the mother.

Tests used to diagnose diabetes insipidus include:

• Water Deprivation Test: While being monitored by professionals, intake of fluids is stopped. During this time, the doctors measure any changes that occur in the patient's urine output, weight, and the concentration of urine (Urine Osmolality) and blood (serum Osmolality). In some cases, synthetic ADH is injected during this test. This helps doctors determine whether the cause is central diabetes insipidus or nephrogenic diabetes insipidus.
• Magnetic resonance imaging (MRI): An MRI allows for the evaluation of any abnormalities in the pituitary gland.
• Blood levels of Antidiuretic Hormone (ADH)
• Genetic testing

The treatment options for diabetes insipidus depend on the type of disease. The treatment options include:

• Central Diabetes Insipidus: Mild diabetes insipidus can be managed by increasing the intake of water, especially in young individuals. Desmopressin, a synthetic hormone, is prescribed to replace ADH. It is administered in the form of either a tablet, IV or nasal spray. The dose is adjusted as per the urine output and monitoring the electrolyte levels. If not monitored properly, intake of desmopressin can cause water retention and low sodium levels in the blood.
• Nephrogenic Diabetes Insipidus: Doctors often recommend a low-salt diet to reduce urine production by kidneys. Drugs such as hydrochlorothiazide may be prescribed to improve symptoms. If the cause of nephrogenic diabetes insiders is one of the medications, the doctor may change it to some other alternative.
• Gestational Diabetes Insipidus: Synthetic hormone administration such as desmopressin helps treat gestational diabetes insipidus.
• Primary Polydipsia: Polydipsia has no specific treatment other than lowering the intake of fluid. If the condition is associated with a mental illness, treating it may relieve the symptoms.

Some risk factors associated with diabetes insipidus are as follows:

• Family history of diabetes insipidus
• Metabolic disorders such as high blood calcium or low blood potassium levels
• Brain surgery or a significant head injury.
• Nephrogenic diabetes insipidus present since birth
• Ongoing medicines that contribute to kidney problems, such as bipolar disorder-linked medicines and diuretics

Diabetes insipidus is associated with the following complications:

• Dehydration, if severe, can cause dizziness, sluggishness, nausea, and vomiting.
• Imbalances in the electrolytes, such as sodium and potassium levels
• Weakness
• Confusion
• Muscle cramps

Reviewed by Dr Anshu Alok, Senior Consultant - Endocrinology & Diabetes on 06-Jan-2023.