Bartter's syndrome, also known as is hypokalemic alkalosis with hypercalciuria, is a rare inherited disorder characterized by growth deficiency, potentially resulting in short stature; muscle weakness; cramps; and/or loss of potassium from the kidneys (renal potassium wasting). In some cases, affected individuals may exhibit mental retardation. Individuals with Bartter's Syndrome have a disturbance in their acid-base ratio (i.e., an accumulation of base or loss of acid) associated with
a loss of potassium (hypokalemic alkalosis). Low amounts of potassium may result from overproduction of a certain hormone (aldosterone) that is essential in controlling blood pressure and regulating sodium and potassium levels (hyperaldosteronism).
Bartter's syndrome is usually hereditary and is caused by a recessive gene; thus, a person with the disorder has inherited two recessive genes for the disorder, one from each parent. The abnormal gene causes the kidney to excrete excessive amounts of sodium, chloride, and potassium. The loss of sodium and chloride leads to mild dehydration, which causes the body to produce more renin and aldosterone. The increase in aldosterone increases potassium and acid secretion in the kidneys, leading to hypokalemia and metabolic alkalosis.
Clinical features present in infancy or childhood and include anorexia, failure to thrive, polydipsia, polyuria and muscle weakness. Mental retardation may be a feature. It usually occurs in children and growth retardation is frequently associated. Aetiology is unknown. Inheritance is autosomal recessive. Children with Bartter's syndrome grow slowly and appear malnourished. They may have muscle weakness and excessive thirst, may produce large amounts of urine, and may be mentally retarded. The loss of sodium and chloride leads to chronic mild dehydration.
The diagnosis of Bartter's syndrome in young children is based on a physical examination and low levels of potassium, sodium, and chloride in the blood. However, similar findings occur when children with certain eating disorders, such as bulimia nervosa, self-induce vomiting and misuse diuretics.
Many of the consequences of Bartter's syndrome can be prevented by taking potassium supplements and a drug that reduces excretion of potassium into the urine, such as spironolactone (which also blocks the action of aldosterone), triamterene, amiloride, propranolol, or nonsteroidal anti-inflammatory drugs (NSAIDs), such as indomethacin. Drinking adequate amounts of fluids is necessary to compensate for the excessive fluid losses.