Case Study: Distal renal tubular acidosis is an uncommon condition with complex pathophysiology that can present with life-threatening electrolyte abnormalities. We describe a case of 55-year-old woman with previous episodes of severe hypokalemia, severe muscle weakness, nausea and fatigue. She admitted at other hospitals with life- threatening condition due to severe hypokalemia (1.2-1.5) four times. However she only received potassium replacement therapy and doctors could not reveal the real cause of hypokalemia. She suffer from symptoms of dry eye and dry mouth also her mother has Sjögren’s syndrome so she started to take mycophenolate mofetil 1000 mg q.d and methylprednisone 5 mg q.d (started with 32 mg) for the Sjögren’s syndrome since 2016. Initial evaluation revealed hyperchloremic, no anion gap metabolic acidosis ( chloride 121.7 mmol/l, AG-12mEq/L, PH-7.29, HCO3-10.9 mmHg) severe hypokalemia (1.9 mmol/l), GFR-46 ml/min/1.73 m2 . Furthermore, persistent alkaline urine and a positive urinary anion gap (urine pH-7.0, UAG +25.9 mEq/L), suggestive of distal renal tubular acidosis. We performed kidney biopsy it revealed chronic tubulointerstitial nephritis. We started to treat potassium replacement therapy and bicarbonate supplementation. Now, she have been taking sodium bicarbonatis 800 mg b.i.d, potassium replacement therapy for 4 years, also she receive mycophenolate mofetil 500 mg b.i.d and methylprednisone 5 mg q.d according to rheumatologists advice. Her serum potassium, PH level normalized even tough her renal function failed to improve and remained steady with an estimated glomerular filtration rate of 47-55 ml/min/1.73 m2. Conclusions: Idiopathic hypokalemia should be carefully evaluated to prevent adverse complications, to uncover trigger of it as well as to prevent the progression of chronic kidney disease. As we think, kidney failure stabilized by avoiding long lasting distal renal tubular acidosis and severe hypokalemia. Repeated episodes of unexplained hypokalemia could be an important clue for diagnosis.