a 10 year old presents with thirst and bed wetting. Investigations revealed low potassium, sodium and an alkalosis. Blood pressure is normal. What is the diagnosis?
- Bartter syndrome
- There are five gene defects known to be associated with Bartter syndrome. 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 sodium. Persons with Bartter syndrome lose too much sodium through the urine. This causes a rise in the level of the hormone aldosterone and makes the kidneys remove too much potassium from the body. This is known as potassium wasting. The condition also results in an abnormal acid balance in the blood called hypokalemic alkalosis.
This disease usually occurs in childhood. Symptoms include: ConstipationGrowth failureIncreased frequency of urinationLow blood pressureKidney stoneMuscle cramping and weakness
The diagnosis of Bartter syndrome is usually suspected 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 and there is a tendency toward low blood pressure. Other signs of this syndrome include:High levels of potassium, calcium, and chloride in the urineHigh levels of the hormones renin and aldosterone in the bloodLow blood chlorideMetabolic alkalosisThese 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.