Rapid correction of severe hyponatremia can result in osmotic demyelination syndrome. Patients with severe hyponatremia and renal failure requiring dialysis pose a therapeutic challenge since the use of conventional intermittent hemodialysis will result in a rapid correction of the serum sodium level. We report the case of a 52-year-old woman with extreme hyponatremia and severe acute kidney injury, who was successfully treated with continuous venovenous hemodialysis using a modified dialysate solution with a low sodium concentration that was adjusted on a daily basis.