Treatment of severe hyponatremia with continuous renal replacement therapy: A case and review of corrective strategies

Treatment of severely hyponatremic patients with continuous renal replacement therapy (CRRT) presents a unique challenge given the lack of commercial options for hypotonic replacement solutions or dialysate. We report the case of a 55-year-old male who presented with profound, symptomatic hyponatremia in the setting of acute kidney injury (AKI). The patient was found to have a serum sodium concentration of 97 mEq/L because of free water retention that occurred during severe AKI from viral gastroenteritis and rhabdomyolysis. Continuous veno-venous hemofiltration (CVVH) was required for AKI complicated by hyperkalemia, metabolic acidosis, and uremia. To prevent overcorrection of serum sodium, replacement fluids customized to natremic status had to be prepared. Conventional replacement fluid was modified on a daily basis to create hypotonic solutions with successively higher sodium concentrations. Over the course of a week, serum sodium successfully improved in a controlled and safe fashion. This case incorporates and reviews the variety of methods that have been used to safely manage severe hyponatremia with CRRT.