Bartter's syndrome involves a group of symptoms and signs:

• Enlargement of certain kidney cells
• Alkalosis associated with reduced potassium (hypokalemic alkalosis)
• Increased production of the hormone aldosterone (see the aldosterone test)

There is no elevation of blood pressure with Bartter's syndrome, which usually occurs with kidney disease.

The exact cause of Bartter's syndrome is not known. In some cases, it 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, an excessive amount of potassium is excreted from the body. This is also known as potassium wasting.

This disease usually occurs in childhood. Symptoms include muscle cramping and weakness, constipation, increased frequency of urination, and growth failure.

The diagnosis of Bartter's syndrome is usually made by finding low levels of potassium in the blood. The potassium level is usually less than 2.5 mEq/L. Other signs of this syndrome include:

• Normal blood pressure
• Low blood chloride
• Metabolic alkalosis (blood is more alkaline that normal)
• High blood levels of the hormones renin and aldosterone (both are involved in the regulation of potassium by the kidney)
• High levels of potassium and chloride in the urine

These same signs and symptoms can also occur in people who have taken excessive amounts of diuretics or laxatives. Urine tests can be done to exclude these causes.

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

Bartter's syndrome is treated by keeping the blood potassium level above 3.5 mEq/L. This is achieved through a diet rich in potassium. Some patients also require salt and magnesium supplements.

The long term prognosis for patients with Bartter's syndrome is not certain. Infants who experience severe growth failure typically grow normally with treatment. Studies are being done to see if these children have decreased mental functioning, which can occur if potassium levels are abnormal for too long. While 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 not growing well, is urinating frequently, and is having muscle cramps.