Estimation of protein intake using urinary urea nitrogen in patients with liver cirrhosis

Abstract

Objective. Evaluation of protein intake of patients with liver cirrhosis (LC) would facilitate optimal nutritional support. However, this has never been done based on urinary urea nitrogen (UUN). The aim of this study was to determine the usefulness of the estimated protein intake (EPI) based on UUN in patients with LC. Material and methods. Eighty-two patients with LC were enrolled in this study. The actual protein intake (API) was defined as the dietary protein intake (1.0 g/kg/day) plus supplementation of any enteral diets containing branched-chain amino acids (BCAA). We calculated EPI from UUN using the formula [(UUN (g/day) + 0.031 × body-weight (kg)) ×0.625]. We examined the correlation between EPI and API and the EPI/API ratio (EAR), and the correction based on the results. Results. A significant positive correlation was found between API and EPI (r=0.72, p<0.001). The EAR in all patients was 0.82±0.13. EPI × 1.2 was the correction needed to adjust EAR to 1. The corrected EPI was correlated with API (r=0.704, p<0.001). The corrected EAR of all 82 patients was 0.99±0.16. Conclusions. EPI calculated from UUN is a useful tool for optimal nutritional support in LC patients, and our correction greatly improves EPI accuracy.