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Kidney Week

Abstract: PO1151

Extreme Hyponatremia with Serum Sodium Less Than 100 mEq/L: A Case Report and Review of the Literature

Session Information

Category: Fluid, Electrolyte, and Acid-Base Disorders

  • 902 Fluid, Electrolyte, and Acid-Base Disorders: Clinical


  • Basil, Kirti, UMass Memorial Medical Center, Worcester, Massachusetts, United States
  • Ralto, Kenneth M., UMass Memorial Medical Center, Worcester, Massachusetts, United States

Hyponatremia is the most common electrolyte abnormality in hospitalized patients and is associated with increased mortality, hospital length of stay and cost. Rapid overcorrection of hyponatremia can increase the risk of osmotic demyelination syndrome (ODS) which can have debilitating and often fatal consequences. Extreme hyponatremia with serum sodium concentration less than 100 mEq/L is rare, but is associated with high a rate of morbidity and mortality.

Case Description

A 52-year-old woman presented with a one-week history of weakness and fatigue. She was cachectic and had signs of severe hypovolemia and malnutrition. Her serum sodium concentration was less than 100 mEq/L on three separate samples. She did not have any focal neurological deficits or any witnessed seizures. Additionally, she was found to have oliguric acute kidney injury and critical hyperkalemia. She was treated with aggressive volume expansion with subsequent increase in serum sodium concentration and resolution of AKI and hyperkalemia. Desmopressin and 5% dextrose infusion were used to prevent rapid overcorrection of hyponatremia and minimize the risk for ODS. Her sodium level was corrected at the recommended rate of 6 mEq/L per day. She was discharged with serum sodium concentration of 136 mEq/L on hospital day 16 and did not have any long-term neurological sequelae.


Extreme hyponatremia with serum sodium concentration less than 100 mEq/L is a rare but critical situation. Review of the previously published cases found that the main risk factors are female gender, age greater than 40 years, malnutrition, alcohol use, thiazide use or SIADH due to antidepressant use. Serum osmolality should be used to estimate serum sodium concentration and guide the rate of correction if the precise sodium value below 100 mEq/L cannot be determined. Careful management is required due to the high risk of ODS in these patients and proactive administration of desmopressin is recommended to avoid overcorrection. Continuous venovenous hemofiltration with hypotonic replacement fluid is an effective strategy for patients with extreme hyponatremia who also require renal replacement therapy for AKI and/or critical hyperkalemia.