Supplementary Material for: The Diagnostic Challenge of Potassium-Wasting and Hypertension in Pregnancy: Lessons from a Geller Syndrome Workup

Background:
Hypokalemia in pregnancy is usually attributed to benign causes, yet persistent hypokalemia with hypertension raises concerns for rare renal potassium-wasting disorders. Among these, Geller syndrome, a rare mineralocorticoid receptor mutation that can be activated by progesterone, can precipitate severe hypokalemia and hypertension unique to pregnancy, due to heightened receptor sensitivity. This case underscores the need to recognize and systematically evaluate potassium-wasting syndromes in pregnancy to optimize outcomes and inform clinical decision-making.

Case Presentation:
We present a 33-year-old woman, G6P2, at 21w6d weeks of gestation, presented with abdominal pain, marked hypokalemia (2.6 mEq/L), and systolic blood pressures in the 150s. She reported no previous history of hypertension or diuretic use and had no significant family history. Initial assessment excluded common etiologies, such as pre-eclampsia, prompting an expanded renal workup. Laboratory findings revealed profound renal potassium-wasting, evidenced by a trans-tubular potassium gradient of 11 and a urine potassium-to-creatinine ratio of 45, alongside low aldosterone levels, normal cortisol and thyroid function. She experienced persistent hypokalemia despite aggressive repletion which led to suspicion of Geller syndrome. Continued potassium supplementation, dietary guidance, and fetal delivery eventually led to stable potassium levels.

Conclusion:
This case highlights the diagnostic complexities of addressing refractory hypokalemia and hypertension in pregnancy, advocating for the consideration of rare etiologies like Geller syndrome. Although negative in this instance, the suspicion of Geller syndrome informed a meticulous diagnostic approach, underscoring the importance of a comprehensive evaluation and genetic counseling in similar presentations. Such awareness can enhance clinicians’ diagnostic frameworks, equipping them to identify and manage rare syndromes if needed. By expanding the differential diagnosis for persistent hypokalemia and hypertension in pregnancy, this case underscores the potential for improved maternal-fetal outcomes through informed and targeted management strategies.

Keywords:
Hypokalemia, Hypertension in Pregnancy, Electrolyte Imbalance, Geller Syndrome, Mineralocorticoid Receptor Mutation, Potassium Wasting Disorders, Genetic Testing in Nephrology