A Case of Recurrent Gestational Hypokalemia Due to an Exaggerated Physiological Response to Pregnancy: The Importance of Using Pregnancy-Specific Reference Ranges.

Hypokalemia in pregnancy can occur secondary to hemodilution of pregnancy, physiological changes during pregnancy, or other pathological conditions. It should be investigated the same way as in non-pregnancy with particular emphasis on the importance of using pregnancy-specific reference ranges when interpreting clinical laboratory test results. Here, we present a case of a woman who had late-trimester gestational hypokalemia requiring potassium supplementation affecting four consecutive pregnancies. We thought that there was accompanying hypomagnesemia and hypobicarbonatemia in previous pregnancies, so we suspected a form of renal tubular dysfunction exacerbated by pregnancy. Subsequent investigation and the use of pregnancy-specific reference ranges revealed that this was an exaggerated physiological response to pregnancy.