Hyperkalemic Renal Tubular Acidosis as Manifestation of Primary Adrenal Insufficiency: A Case Report and Review of the Pathophysiology

Abstract

Hyperkalemic renal tubular acidosis (RTA), or type 4 RTA in adults, typically is an acquired condition characterized by non-anion gap metabolic acidosis that mostly suggests a dysfunction in the secretion of potassium, ammonium, and hydrogen ions of kidney tubules. It should be considered in hyperkalemic patients with moderately decreased glomerular filtration rate (GFR). This condition can be caused by hypoaldosteronism or impaired function of the cortical collecting duct. We present a case of a 45-year-old male who came to the emergency department with a chief complaint of nausea. A hyponatremia, hyperkalemia with normal anion gap metabolic acidosis, and mildly reduced glomerular filtration rate (GFR) were shown in his laboratory findings, suggesting a condition of hyperkalemic renal tubular acidosis caused by adrenal insufficiency. These findings have been confirmed by low serum cortisol, elevated adrenocorticotropic hormone (ACTH), low aldosterone levels, and an imaging result of adrenal mass. After receiving steroid replacement therapy, the patient steadily improved.