Correcting for protein in parenteral nutrition does not affect hyponatremia risk

Last Updated: 2017-12-13

By Reuters Staff

NEW YORK (Reuters Health) - Most patients receiving parenteral nutrition (PN) have hyponatremia, and PN composition does not appear to affect hyponatremia risk, according to a new study.

Hyponatremia is the most common electrolyte disorder among inpatients, and is linked to increased mortality, Dr. Emilia Gomez-Hoyos of Universidad de Valladolid in Spain and colleagues note in their report, online November 30 in the European Journal of Clinical Nutrition.

Hospitalization increases hyponatremia risk, they add, and it is possible that receiving PN does as well. However, many patients on PN have hypoproteinemia, which leads to overestimation of serum sodium levels (SNa) when indirect electrolyte methodology is used.

Dr. Gomez-Hoyos and her colleagues looked at medical records for 222 inpatients on PN (median age, 75). The most common indications for PN were gastrointestinal surgery (43%), bowel rest (26%), and bowel obstruction (14%).

When the researchers corrected SNa for serum total protein (TP), 81% of patients had hyponatremia (SNa <135 mmol/liter). When they did not correct for TP, only 43% were classified as hyponatremic.

Sixty-four percent of patients who were eunatremic at baseline developed hyponatremia while on PN, according to SNa levels corrected for TP. Without correction, 28% would be considered to be hyponatremic.

Volume, osmolarity, sodium and osmols administered were similar for the groups that did or did not develop hyponatremia, the researchers found.

"Most patients receiving parenteral nutrition present with hyponatremia," Dr. Gomez-Hoyos and colleagues write. "To correctly assess hyponatremia, direct electrolyte methodology should be used, or indirect electrolyte values corrected for total proteins. The development or absence of this electrolyte disorder is not a function of the composition of the parenteral nutrition formula, and could be induced by non-osmotic (arginine vasopressin) secretion."

Dr. Gomez-Hoyos was not available for an interview by press time.

SOURCE: http://bit.ly/2ymCXos

Eur J Clin Nutr 2017.