Hypokalaemia in Type-4 Renal Tubular Acidosis: A Rare Presentation

Abstract

Proximal/Type-2 Renal Tubular Acidosis (RTA) occurs due to impairment of bicarbonate absorption in the proximal tubule and is mainly characterised by hypokalaemia and metabolic acidosis. There are various causes of proximal RTA like genetic, cystinosis, Wilson’s disease, drugs and toxins, vitamin D deficiency, hyperparathyroidism, amyloidosis. Vitamin D deficiency is one of the uncommon causes and is more common in elderly. Hereby, authors present a case report of a diabetic and hypothyroid 30-year-old female, who presented with chronic limb weakness, myalgia and bilateral leg swelling. After detailed history taking, clinical examination and laboratory investigations, she was diagnosed with nephrotic syndrome and proximal RTA associated with vitamin D deficiency. She had hypokalaemia with acidosis initially and was managed with diuretics, Angiotensin Converting Enzyme (ACE) inhibitors, vitamin D and potassium supplementation, after which, she developed hyperkalaemia with acidosis. She was evaluated for hyperkalaemic RTA and its common causes and was diagnosed with hyperkalaemic RTA associated with diabetes. Thus, treatment of type-2 RTA due to vitamin D deficiency, led to unmasking of underlying type-4 RTA due to diabetic nephropathy.

Keywords

• angiotensin converting enzyme inhibitors
• diabetes mellitus
• vitamin d deficiency