Bartter syndrome

Bartter syndrome is a rare inherited kidney disorder that disrupts the normal reabsorption of salt in the thick ascending limb of the loop of Henle, a segment of the kidney's filtering tubules. The faulty salt transport forces the kidneys to waste sodium, potassium, and chloride, which the body partly compensates for by producing more of the hormones that regulate blood pressure and fluid balance; the result is a distinctive pattern of low blood potassium, an alkaline blood pH, and blood pressure that stays normal or low despite the hormonal activity. Genetic mutations in several different genes can cause the condition, each affecting a different protein involved in salt transport along the nephron, which has led physicians to classify Bartter syndrome into five genetic types, from mutations in the sodium-potassium-chloride cotransporter gene SLC12A1 in type 1 to mutations in the calcium-sensing receptor gene CASR in type 5. A related but generally milder inherited salt-wasting disorder, Gitelman syndrome, affects a different part of the same kidney tubule system. The syndrome is named for the American endocrinologist Frederic Bartter, who together with Pacita Pronove first described it in 1960, with additional case reports following in 1962.