Gordon, You're Bananas! A Case of Resistant Hyperkalemia

Introduction: Gordon syndrome, also known as familial hyperkalemic hypertension or pseudohypoaldosteronism type II, is a type IV renal tubular acidosis (RTA) and presents during adolescence or young adulthood. Its pathology is due to gene mutations that affect electrolyte transporters in the renal distal tubules and can be difficult to clinically identify from other common diagnoses. In this case, we highlight Gordon syndrome as an alternative diagnosis for a patient with suspected acute heart failure exacerbation nonresponsive to standard treatments. Case Description: A 30-year-old male with a history of hypertension presents for worsening dyspnea and leg edema. His family history was significant for early onset hypertension. On exam, he was tachycardic, hypertensive, and had diffuse lung crackles and severe edema. Labs indicated hyperkalemia, NAGMA, and elevated BNP. A transthoracic echocardiogram and renal ultrasound were unremarkable. Repeated furosemide and potassium binder doses had inadequate responses, triggering other renal workup. Loop diuretics were discontinued in favor of thiazide diuretics, and he improved, discharging home with instructions to obtain outpatient genetic testing for Gordon syndrome. Labs were significant for an elevated renin, low aldosterone, and normal metanephrine and normetanephrine. Two months later, he was re-evaluated for intermittent edema after being compliant with a thiazide, and his symptoms and laboratory abnormalities were primarily resolved. Discussion: Gordon syndrome, although rare, can resemble more prevalent disorders like heart failure, but can be differentiated by distinct lab results and early onset hypertension. This patient’s volume status and hyperkalemia were also unresponsive to standard heart failure treatments, and in the setting of unremarkable renal and adrenal workup, his ongoing NAGMA, hyperkalemia promoted investigation into a type 4 RTA. His renin was elevated, likely from furosemide administration and its activation of the renin-angiotensin-aldosterone system. His aldosterone however remained suppressed, and he responded well once transitioned to thiazides, which coincides with Gordon syndrome’s pseudohypoaldosterone nature and its sensitivity to that drug class. Recognizing these diagnostic hallmarks in the early stages can expedite accurate diagnosis and the initiation of appropriate treatment, thereby improving patient care outcomes.