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.