Hyponatremia, mg vs. mEq Gone Terribly Wrong: A Cautionary Tale

Introduction: We present a case of a rapid hyponatremia correction due to an improper medication dose conversion calculation. Hyponatremia, a common electrolyte disorder, remains a nephrologist nightmare as it can lead to osmotic demyelination syndrome (ODS). Management of hyponatremia remains challenging and involves an understanding of the relationship between, weight, osmolality, tonicity, and different unit measures. Case Description: 59-year-old female > 50% total body surface area burns complicated by tracheoesophageal fistula s/p complex repair, recurrent aspiration pneumonia, severe malnourishment, chronic hyponatremia, thought due to SIADH managed with salt tabs, presented due to malfunction NG tube, and was found to be hyponatremic at 119 mmol/L. After endoscopic NG tube placement, she was restarted on diet and Salt tabs, 3 tabs q 8 hours (EMR order Thermotabs/chloride 287 mg Sodium 180 mg, Potassium 15mg (540 mg of sodium equal to 72 mEq in 24 hour) with slow improvement on her serum sodium. However, given NG tube clogging issues, the night team changed her tablets into a liquid formulation 540 mEq q8 hr (EMR order liquid sodium chloride 4 mEq/ml). The[SA1] conversion unfortunately was done assuming milligrams and mEq were the same with the patient mistakenly getting 23 times the intended amount of sodium through the NG tube in liquid form, that caused a sodium correction[SA2] from 123 to 145 mmol/L in the next few hours. CT brain showing subarachnoid hemorrhage. MRI brain the next day also showed T2/FLAIR hyperintensity in the pons concerning for myelinolysis. Discussion: Electrolytes dosing errors are well-known and associated with high morbidity and mortality. In general, when a system fails to prevent an adverse outcome, poor communication is almost always a contributing factor. We also identified that a non-standardized sodium formulation’s units in EMR orders (tablets registered in milligrams, while liquid formulations with their concentration mEq/ml) contributed to the adverse event. Our systems heavily rely on the provider’s knowledge, increasing the risk of human error. We hope that standardizing EMR listing of electrolytes replacements to include the mEq content for each formulation and automatically calculate the total prescribed dose will aid in avoiding future errors.