Bartter's syndrome in pregnancy: review of potassium homeostasis in gestation.

A 26-year-old G3P2 Hispanic female presented with acute urinary retention and profound hypokalemia (serum potassium 1.6 mEq/L) during her 13th week of pregnancy. Placement of an indwelling bladder catheter resulted in immediate urine output of 1700 mL. Potassium was administered aggressively and urinary retention resolved. She reported the use of herbal products containing licorice and corn silk tea (zea maize extract). She was taking no medication other than prenatal vitamins and had no known prior medical problems. Despite discontinuance of the herbal supplement and tea and aggressive oral potassium replacement, severe asymptomatic hypokalemia persisted. Twenty-four-hour urine studies and blood chemistry determinations, subsequently, were consistent with Bartter's syndrome. At the time of hospital discharge, she was receiving 480 mEq of oral potassium daily. Potassium-sparing diuretics were not prescribed, because successful pregnancy outcomes have been reported in patients with Bartter's syndrome and Gitelman syndrome without normalization of potassium levels. Hypokalemia (2.5-3.0 mEq/L) persisted throughout an otherwise uncomplicated pregnancy with delivery of a healthy child at 35 weeks of gestation.