What is nephrogenic diabetes insipidus (NDI)?
Nephrogenic diabetes insipidus is when the kidneys cannot react to a hormone that balances fluids. This causes excessive urination and thirst.
NDI is caused by problems with a hormone called antidiuretic hormone or ADH. ADH is created in a part of the brain called the hypothalamus and stored in the pituitary gland. ADH is released when dehydration or loss of fluid occurs. When it is released, it causes the kidneys to hold water, resulting in a reduction in urine.
When an individual has nephrogenic diabetes insipidus, ADH is released but the kidneys do not respond to it correctly. Oftentimes, the kidneys’ ADH sensors are absent or faulty, and the ADH streams by without effect. The kidneys don’t retain enough water. Instead, they discharge diluted urine as though no ADH were present.
Symptoms and causes of nephrogenic diabetes insipidus
The most common signs and symptoms of nephrogenic diabetes insipidus include extreme thirst and excessive urination.
Depending on the seriousness of the condition, urine output can reach 16 quarts (about 15 liters) per day. Typically, a healthy adult will urinate fewer than 3 quarts (about 3 liters) per day.
In some individuals, extreme dehydration can occur. Extreme fluid loss can also cause electrolyte imbalances. Symptoms of electrolyte imbalances include unexplained weakness, lethargy, muscle pain, and irritability. Other signs may include nocturia (getting up at night to urinate) and bed-wetting.
Babies and children who have NDI may have the following symptoms:
- Unexplained fussiness;
- Trouble sleeping;
- Slow growth;
- Loss of weight.
In newborn babies, nephrogenic diabetes insipidus is usually caused by genetics.
In adults with NDI, genetics is not the cause. Electrolyte abnormalities or medications can cause this condition.
Causes of NDI in adults include:
- Lithium, a medication taken for bipolar disorder. Up to 20% of individuals taking lithium will develop nephrogenic diabetes insipidus.
- Other drugs, including demeclocycline (Declomycin), orlistat (Alli, Xenical), and ofloxacin (Floxin).
- Extreme levels of calcium in the blood (hypercalcemia).
- Low levels of potassium in the blood (hypokalemia).
- Kidney disease, particularly polycystic kidney disease.
To counteract dehydration, individuals with nephrogenic diabetes insipidus must drink sufficient amounts of water when they feel thirsty. Newborn babies, children, and elderly individuals must be given water regularly. Individuals who drink enough water will not become dehydrated, but a few hours without water can lead to severe dehydration. A diet that is low in salt and protein may also help.
If diet changes do not help to decrease urine output, a specialist may prescribe medications. Desmopressin is an engineered type of ADH that can treat non-genetic NDI.
NSAIDs and thiazide diuretics can also help to treat nephrogenic diabetes insipidus. Diuretics and NSAIDs increase the amount of sodium and water that are reabsorbed by the kidney, leading to a reduction in urine volume. Diuretics can help to control how much water is discharged from the body through urine.