Primary Sjögren's Syndrome Presenting With Severe Hypokalemia Due to Distal Renal Tubular Acidosis: A Case Report

Primary Sjögren's syndrome is a systemic autoimmune disorder with diverse clinical manifestations. Although exocrine gland dysfunction is the hallmark, renal involvement, particularly distal renal tubular acidosis (type 1 RTA), can occur and may precede classic sicca symptoms. We report a case of a 55-year-old woman presenting with acute lower limb weakness due to severe hypokalemia. Laboratory investigations revealed normal anion gap metabolic acidosis with inappropriately alkaline urine, consistent with type 1 RTA. Further evaluation uncovered subtle sicca symptoms, parotid gland enlargement, and serologic positivity for anti-Ro/SSA and anti-La/SSB antibodies, supporting the diagnosis of primary Sjögren's syndrome. The patient responded well to potassium and bicarbonate supplementation. This case underscores the importance of considering autoimmune etiologies such as primary Sjögren's syndrome in patients with unexplained hypokalemia and tubular acidosis, even in the absence of overt sicca features.