Hypokalemic Periodic Paralysis in a Patient With Primary Sjögren's Syndrome and Distal Renal Tubular Acidosis: A Case Report.

Introduction: Hypokalemic periodic paralysis (HPP) is a severe yet reversible neuromuscular condition precipitated by profound hypokalemia. Autoimmune disorders can exacerbate renal potassium loss resulting in abrupt muscle weakness. Primary Sjögren's syndrome (pSS), an autoimmune disease characterized by exocrine gland insufficiency, can lead to renal tubular dysfunction and episodes of HPP when distal acidification is compromised. Case presentation: A 40-year-old woman was admitted with rapidly progressive, painless quadriplegia for over 2 days. Laboratory tests revealed critical hypokalemia (1.4 mEq/L), metabolic acidosis, and alkaline urine pH, which was consistent with type 1 distal renal tubular acidosis (dRTA). Serologic studies confirmed pSS. Corrective measures included intravenous potassium chloride and sodium bicarbonate along with immunomodulation with intravenous methylprednisolone, followed by oral prednisolone. Discussion: The patient's presentation illustrates how autoimmune-mediated renal tubular dysfunction can precipitate HPP. Failure of distal acid excretion impairs potassium handling, amplifying the risk of potentially life-threatening neuromuscular collapse. Stabilization requires meticulous electrolyte repletion and treatment of the underlying autoimmunity. Restoration of serum potassium levels, acid-base balance, and targeted immunosuppression resulted in rapid clinical improvement. Conclusion: An accurate diagnosis of HPP secondary to dRTA and Sjögren's syndrome requires high clinical suspicion. Prompt recognition and intervention, including immunotherapy and balanced electrolyte replacement, can prevent profound neuromuscular complications and improve patient outcome.