Hyperchloremic Metabolic Acidosis with Negative Urinary Anion Gap in Turner Syndrome

Turner syndrome (TS) is associated with a higher prevalence of autoimmune disorders, including type 1 diabetes mellitus and celiac disease (CD). Gastrointestinal manifestations in such patients may lead to metabolic derangements that can mimic renal tubular acidosis (RTA), posing a diagnostic dilemma. We report a young female with TS and poorly controlled type 1 diabetes mellitus who presented with severe malnutrition, electrolyte abnormalities, and persistent hyperchloremic metabolic acidosis. Initial clinical suspicion was RTA; however, further evaluation demonstrated a negative urinary anion gap, suggesting extrarenal bicarbonate loss rather than a renal etiology. Further workup revealed a positive immunoglobulin A anti-tissue transglutaminase antibody. The patient was started on a gluten-free diet and insulin therapy was reinforced, following which clinical improvement was noticed. Given the ongoing metabolic acidosis with malnutrition, additional workup for gastrointestinal causes revealed a diagnosis of CD contributing to the clinical manifestations.