Hypokalemic paralysis in a patient with Sjögren’s disease: a rare emergency

Renal tubular acidosis (RTA) is the most common renal manifestation in Sjögren’s disease (SjD), typically subclinical but occasionally presenting with severe hypokalemia. A 59-year-old woman with SjD, treated with hydroxychloroquine and pilocarpine, was admitted with sudden quadriparesis, hypotonia, and muscle weakness. Tests showed severe hypokalemia (K + : 1.6 mEq/L), normal anion gap metabolic acidosis, and alkaline urine. ECG revealed U-waves and ventricular bigeminy. Electrolyte replenishment normalized potassium within 48 hours, resolving ECG abnormalities and improving muscle strength. After transfer to the rheumatology department, she developed slurred speech, borderline hypokalemia, and metabolic acidosis. Brain MRI confirmed central pontine myelinolysis (CPM). Kidney biopsy verified RTA due to tubulointerstitial nephritis. Treatment with methylprednisolone (40 mg/day) and cyclophosphamide pulses normalized acid-base status and led to neurological recovery. In SjD, autoimmune-mediated tubulointerstitial inflammation impairs hydrogen ion secretion, causing metabolic acidosis and potassium wasting. Hypokalemic paralysis from RTA is a rare, life-threatening complication. CPM, typically linked to sodium fluctuations, may also relate to SjD activity and metabolic disturbances, requiring heightened clinical suspicion for early detection and management, especially as RTA is often subclinical but can manifest with significant electrolyte imbalances.