Gitelman syndrome and in vitro fertilization-embryo transfer: advancing preconception care in nephrology.

We report a case of a pregnant patient with Gitelman syndrome (GS) who conceived by in vitro fertilization-embryo transfer (IVF-ET). A 39-year-old woman was referred for hypokalemia, with a serum potassium level of 2.2 mEq/L. She had difficulty conceiving spontaneously. Because of her age, her hypokalemia could be exacerbated by pregnancy. We provided preconception care and managed her pregnancy by frozen-thawed embryo transfer with careful monitoring of the K levels. However, her serum K level dropped to 2.5 mEq/L at 8 weeks of gestation. It was expected that her K demand would increase with pregnancy; hence, she required hospitalization and a 1.5-fold increase in replacement dose to maintain her K levels. At 11 weeks of gestation, her serum K level rose to 3.0 mEq/L. The baby was born adequately sized after 38 weeks of gestation via vaginal delivery. The patient's K levels were stable during the postpartum period. Genetic testing revealed three heterozygous missense variants in SLC12A3 that were consistent with GS. In conclusion, preconception care and cooperation between internal medicine and obstetrics led to an excellent and successful delivery of an IVF fetus in an older patient with GS. There are no guidelines for electrolyte disorders in pregnancy, and only a few studies have reported on GS during pregnancy, including detailed postpartum assessments.