Endocrine Abstracts

Introduction: Pseudohypoaldosteronism type 2 (PHA2), also known as Gordon syndrome is a rare inherited form of low-renin hypertension associated with hyperkalaemia and hyperchloremic metabolic acidosis in patients with a normal glomerular filtration rate (GFR). PHA2 is the result of mutations in a family of serine-threonine kinases called with-no-lysine kinases (WNK) 1 and WNK4. These enzymes regulate electron channels in the aldosterone sensitive distal nephron, resulting in disrupted electron balance. PHA2 is a genetically and phenotypically heterogeneous entity, associated with high sensitivity to thiazides.

Case report: A 57 year old patient with anamnesis of treatment-naïve hypertension and foramen ovale apertum enclosed with occluder was admitted to the hospital for surgery due to adrenal mass – a typical adenoma found on abdominal CT 5 years ago with the diameter of 1.7 cm. Laboratory test results excluded Cushing syndrome, but primary hyperaldosteronism was not suspected due to persisting hyperkalaemia. Abdominal CT scan was repeated to evaluate the growth dynamics of the adrenal mass, revealing an enlarged left adrenal gland with a hypodense (9 HU) vascular mass 4.1 cm in diameter. Pre-operative testing revealed several laboratory abnormalities: hyperkalaemia 5.6 mmol/l (3.5–5.1) and hyperchloraemia 106 mmol/l (95–105), low plasma renin <0.5 μU/ml (4.4–46.1), normal aldosterone 95.8 pg/ml (25.2–392.0), normal GFR 100.5 ml/min, acidic urine pH 4.8 and decreased potassium excretion 23 mmol per day (25–125). Considering the findings of low renin hypertension with hyperkalaemia and normal GFR the diagnosis of PHA2 was established. The patient was started on antihypertensive treatment with thiazide diuretic and underwent left adrenalectomy. Histology conformed to hormonally inactive adrenocortical adenoma, Weiss score 2.

Conclusions: The current case demonstrates the challenges of differential diagnosis of low renin hypertension depicting the characteristic findings of PHA2. It should be noted that upon correct diagnosis this form of low renin hypertension is easily treatable with thiazide diuretics.