Distal renal tubular acidosis and nephrocalcinosis as the initial manifestations of primary Sjögren’s syndrome in adolescence

Abstract

Renal tubular acidosis (RTA) is an uncommon cause of metabolic acidosis in adolescents. We report the case of a 15-year-old girl with primary Sjögren’s syndrome (SS) who presented with distal RTA, manifesting as flank pain and nephrocalcinosis. Laboratory evaluation revealed hypokalemia, normal anion gap metabolic acidosis, and alkaline urine, whereas imaging confirmed medullary nephrocalcinosis. Autoimmune serology and labial gland biopsy established the diagnosis of primary SS. The patient responded well to oral potassium supplementation and alkali therapy, with marked clinical improvement. This case underscores the importance of considering autoimmune etiologies in adolescents presenting with unexplained RTA and nephrocalcinosis, as early recognition and treatment can prevent long-term renal complications.