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In Bartter syndrome, the kidneys excrete excessive amounts of electrolytes (potassium, sodium, and chloride), resulting in electrolyte abnormalities in the blood.
Bartter 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. In affected people, the kidneys excrete excessive amounts of sodium, chloride, and potassium. The loss of sodium and chloride leads to excessive urine production and thus 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 low blood potassium (hypokalemia) and loss of acids in the blood that causes blood pH to be alkaline (metabolic alkalosis–see Acid-Base Balance: Alkalosis).
Symptoms and Diagnosis
Children with Bartter 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. Abnormally low blood pressure (hypotension) may occur.
The diagnosis of Bartter syndrome in young children is based on a physical examination and on the characteristic abnormalities of electrolytes in blood and urine. Abnormal results are confirmed by finding high levels of certain hormones (renin, aldosterone) on blood tests. However, similar findings may occur when children with certain eating disorders, such as bulimia nervosa, self-induce vomiting and misuse diuretics.
Treatment
Many of the consequences of Bartter 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, angiotensin-converting enzyme (ACE) inhibitors, or nonsteroidal anti-inflammatory drugs (NSAIDs), such as indomethacin. Drinking adequate amounts of fluids is necessary to compensate for the excessive fluid losses.
Last full review/revision December 2006 by Peter C. Brazy, MD
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