Gitelman Syndrome in Pregnancy

Introduction: Gitelman syndrome (GS) is a rare genetic disorder of the distal convoluted tubule caused by loss-of-function mutations in the SLC12A3 gene, which encodes the thiazide-sensitive NaCl co-transporter. Impaired sodium and chloride reabsorption leads to hypokalemia, hypomagnesemia, hypocalciuria, and secondary activation of the renin-angiotensin-aldosterone system. Symptoms include fatigue, muscle cramps, salt cravings, and postural hypotension. In pregnancy, increased GFR and plasma volume can worsen symptoms, making electrolyte balance critical. While outcomes are often favorable, poorly controlled disease can threaten maternal and fetal health. Case Description: A 31-year-old G1P0 woman at 12 weeks’ gestation was referred for electrolyte abnormalities. She reported persistent nonbloody vomiting and had a history of hyperprolactinemia and prior unexplained electrolyte issues. Labs showed K 2.5 mmol/L, Mg 1.0 mg/dL, Na 134 mmol/L, and Cr 0.35 mg/dL. EKG showed incomplete RBBB with T-wave inversions. Fetal ultrasound was reassuring. She was treated with IV magnesium sulfate and potassium chloride and admitted. Hospital management included oral magnesium and IV/PO potassium. Ongoing losses raised concern for renal wasting. A 24-hour urine collection showed high potassium, sodium, and magnesium with low calcium, supporting Gitelman syndrome, later confirmed by genetic testing. She was discharged on high-dose oral and outpatient IV magnesium. Electrolytes remained unstable due to GI intolerance. At 23 weeks, she was readmitted. Amiloride was started and increased to BID, improving control. At 36 weeks, she developed severe IUGR and delivered via C-section at 37 weeks. Postpartum, amiloride was stopped for breastfeeding. Labs improved, and genetic counseling was advised for the infant. Discussion: GS poses unique challenges in pregnancy. When oral and IV supplementation fail, amiloride, may be effective. It is FDA category B with no known teratogenicity. This case supports its cautious use when benefits outweigh risks and highlights the need for multidisciplinary care. Comparison of Management Strategies for Gitelman Syndrome in Pregnancy: - Author/Year Treatment Strategy Gestational Age at Initiation Medications Used Maternal Outcome Fetal Outcome Notes Liu et al., 2023 Oral K/Mg supplementation only First trimester Potassium chloride, magnesium oxide Persistent electrolyte imbalance Intrauterine growth restriction (IUGR) in some cases GI intolerance limited therapy effectiveness Rashid et al., 2022 Oral K/Mg + IV supplementation First trimester IV magnesium sulfate, oral K/Mg Suboptimal control Adverse fetal outcome (stillbirth) Highlighted importance of early and aggressive intervention Wang et al., 2005 Oral K/Mg + Amiloride Early second trimester Amiloride, oral and IV K/Mg Improved electrolyte control Healthy term infant Amiloride well-tolerated Current Case (2025) High-dose oral K/Mg + IV + Amiloride Mid-second trimester (23 weeks) Amiloride 5–10 mg/day, KCl 20 mEq (12 tabs TID), MgO 400 mg (12 tabs TID), IV K/Mg Improved control; postpartum stability Viable infant at 37 weeks, severe IUGR Amiloride improved tolerance and stabilization where oral therapy failed De Arriba et al., 2012 Oral + IV + Spironolactone Second trimester Spironolactone, K/Mg Improved electrolytes Healthy female child of 3 kg Limited use due to anti-androgenic concerns in male fetuses