Congenital hypokalemia with hypercalciuria in preterm infants: a hyperprostaglandinuric tubular syndrome different from Bartter syndrome.

A congenital hypokalemic tubular disorder is described with many features resembling Bartter syndrome. Additional features include prenatal onset with polyhydramnios and premature labor; failure to thrive; episodes of fever, vomiting, diarrhea, and renal electrolyte and water wastage; hypercalciuria; nephrocalcinosis; and osteopenia. Unlike Bartter syndrome, there is no defect in tubular reabsorption of chloride. Urinary levels of prostaglandin E2 and 7 alpha-hydroxy-5,11-diketotetranorprosta-1,16-dioic acid are selectively elevated, indicating marked stimulation of renal and systemic PGE2 production. Chronic suppression of PGE2 activity by indomethacin corrects most of the abnormalities, and there is an immediate decompensation of the disease on indomethacin withdrawal. We conclude that these preterm infants have a distinct variety of hypokalemic tubular disorders rather than a variant of Bartter syndrome, because renal and systemic hyperprostaglandinism ranks high in the pathogenic chain of events, and the suppression of PGE2 hyperactivity is associated with significant improvement in the development (and probably in the prognosis) of the affected children.