pediatrics
Bartter Syndrome and Gitelman Syndrome
Diagnosis
Serum and urine electrolyte levels Exclusion of similar disorders Genetic testing Bartter syndrome and Gitelman syndrome should be suspected in children with characteristic symptoms or incidentally noted laboratory abnormalities, such as Metabolic Alkalosis and Diagnosis is by exclusion of other disorders: Primary and secondary aldosteronism can often be distinguished by the presence of hypertension and normal or low plasma levels of renin (see table). Surreptitious vomiting or laxative abuse can often be distinguished by low levels of urinary chloride (usually<20 mmol/L). Surreptitious diuretic abuse can often be distinguished by low levels of urinary chloride and by a urine assay for diuretics. A 24-hour measurement of urinary calcium or the urine calcium/creatinine ratio may help distinguish the two syndromes; the levels are typically normal to increased in Bartter syndrome and low in Gitelman syndrome. Definitive diagnosis, including identification of disease subtypes, is through genetic testing, which is now becoming more widely available. Children of carriers have a 25% chance of being affected by a recessive form, so asymptomatic siblings should be screened for electrolyte derangements, primarily hypokalemia and metabolic alkalosis, as well as hypomagnesemia. Parents of an affected child can consider consulting a genetic counselor regarding prenatal and preimplantation genetic screening for subsequent pregnancies. 