Distal Renal Tubular Acidosis due to Primary Sjögren's Syndrome: Presents as Hypoakalemic Paralysis with Hypokalemia-Induced Nephrogenic Diabetes Insipidus.

Classic distal renal tubular acidosis (dRTA) is characterized by inability to acidify the urine maximally (to <pH 5.5) in the presence of systemic acidosis. dRTA is found in 5% of patients with Sjögren's syndrome. The major clinical renal manifestation of patients with Sjögren's syndrome is tubulointerstitial involvement, leading to dRTA, impaired concentrating ability, hypercalciuria, and less frequently proximal tubular defects. Nephrogenic diabetes insipidus (DI) is characterized by reduced responsiveness to vasopressin, leading to hypotonic polyuria and consequent hypernatremia. The common causes of acquired nephrogenic DI include drugs, hypercalcemia, hypokalemia, sickle cell anemia, polycystic kidney disease, obstructive nephropathy, and other tubulointerstitial diseases. Our patient was a 32-year-old female presenting with acute flaccid paralysis requiring ventilator support. On investigation, she had nonanion gap metabolic acidosis with urine pH of 7.0 and hypokalemia with hypernatremia. During hospital course, the patient developed hypotonic polyuria and hypernatremia which failed to respond to vasopressin but corrected with potassium replacement and intravenous free fluids. On further investigation, antinuclear antibody was positive with strong positive anti-Ro antibody which pointed to diagnosis of Sjögren's syndrome. With potassium correction, patient's weakness and polyuria improved, and the patient was discharged on oral potassium and bicarbonate supplements.