CT-Measured Psoas Muscle Density as a Predictive Factor for Hypophosphatemia Associated with Refeeding.

BACKGROUND Initiation of parenteral nutrition (PN) after a period of starvation can be complicated by refeeding syndrome (RFS). RFSs is associated with electrolyte abnormalities including hypomagnesemia, hyponatremia, and most commonly hypophosphatemia. Risk factors associated with the development of RFS include recent weight loss, low BMI, and electrolyte deficiencies, however, these associations are not strong. We hypothesized that a validated measure of nutritional risk, CT-measured psoas muscle density, can be used to predict the development of hypophosphatemia associated with RFS. METHODS A retrospective analysis of surgical patients initiated on PN with an abdominal CT scan within the past three months was conducted. CT-measured psoas muscle density was assessed as a predictive variable for the development of electrolyte abnormalities. Daily electrolyte and clinical outcome measures were recorded. RESULTS 109 patients were stratified based on Hounsfield unit area calculation (HUAC). The lowest 25th percentile of patients had HUAC < 25. Low HUAC was associated with a significant percent decrease in phosphate levels from baseline to PN day 3 (p<0.01), and significant difference in serum phosphate value on PN day 3 (p<0.01). The low muscle density quartile also experienced longer days on the mechanical ventilator (p = 0.01) compared to patients with a higher psoas muscle density. CONCLUSION Psoas muscle density predicted the development of hypophosphatemia in patients initiated on PN. This measurement may aid in identifying patients at highest risk of experiencing RFS. A MPHU < 25 HU may prompt additional precautions including additional phosphate replacement and slower initiation of PN. This article is protected by copyright. All rights reserved.