Antenatal Bartter syndrome is a phenotypic variant of Bartter syndrome (see this term) presenting antenatally with maternal polyhydramnios, pre-term delivery and postnatally with polyuria, and nephrocalcinosis. Hypokalemic alkalosis, increased levels of plasma renin and aldosterone, low blood pressure and vascular resistance to angiotensin II are characteristically associated. Genotypically they comprise Type 1 and Type 2 Bartter syndrome