Bartter syndrome refers to a rare group of conditions that affect the kidneys. People with Bartter syndrome have a loss of potassium (hypokalemic alkalosis) and a rise in the hormone aldosterone.

See also: Aldosterone test

In some cases, Bartter syndrome may be genetic and the condition is present from before birth (congenital).

The condition is thought to be caused by a defect in the kidney's ability to reabsorb potassium. As a result, the kidneys remove too much potassium from the body. This is also known as potassium wasting.

This disease usually occurs in childhood. Symptoms include:

• Constipation
• Growth failure
• Increased frequency of urination
• Muscle cramping and weakness

The diagnosis of Bartter syndrome is usually made by finding low levels of potassium in the blood. The potassium level is usually less than 2.5 mEq/L. Unlike other forms of kidney disease, this condition does not cause high blood pressure. Other signs of this syndrome include:

• High levels of potassium, calcium, and chloride in the urine
• High levels of the hormones renin and aldosterone in the blood
• Low blood chloride
• Metabolic alkalosis

These same signs and symptoms can also occur in people who have taken too many diuretics or laxatives. Urine tests can be done to rule out these causes.

In Bartter syndrome, a biopsy of the kidney typically shows too much growth of kidney cells called the juxtaglomerular apparatus. However, this is not found in all patients, especially in young children.

Bartter syndrome is treated by keeping the blood potassium level above 3.5 mEq/L. This is done by following a diet rich in potassium.

Many patients also need salt and magnesium supplements, as well as medicine that blocks the kidney's ability to get rid of potassium. High doses of nonsteroidal anti-inflammatory drugs (NSAIDs) may also be used.

The long-term outlook for patients with Bartter syndrome is not certain. Infants who have severe growth failure may grow normally with treatment. Although most patients remain well with ongoing treatment, some develop kidney failure.

Kidney failure is a possible complication.

Call your health care provider if your child is:

• Having muscle cramps
• Not growing well
• Urinating frequently

Tolkoff-Rubin N. Treatment of irreversible renal failure. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 133.

Mitch WE. Chronic kidney disease. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 131.