pediatrics
Bartter Syndrome and Gitelman Syndrome
Pathophysiology
Bartter syndrome and the more common Gitelman syndrome result from Derangedsodium chloridereabsorption In Bartter syndrome, the defect is in the ascending thick limb of the loop of Henle. In Gitelman syndrome, the defect is in the distal tubule. In both syndromes, the impairment ofsodium chloridereabsorption causes mild volume depletion, which leads to increases in renin and aldosterone release, resulting in potassium and hydrogen losses. In Bartter syndrome, there is increased prostaglandin secretion as well as a urinary concentrating defect due to impaired generation of the medullary concentration gradient. In Gitelman syndrome, hypomagnesemia and a low urinary calcium excretion are common. In both disorders, sodium wasting contributes to a chronic mild plasma volume contraction reflected by a normal to low blood pressure despite high renin and angiotensin levels. The features at clinical presentation vary ( see Table: Some Differences Between Bartter Syndrome and Gitelman Syndrome ). 