Substrate oxidation in patients with cirrhosis: Comparison with other nutritional markers

Background: Malnutrition in patients with hepatic cirrhosis is associated w ith abnormal fuel metabolism marked by reduced glucose oxidation and increa sed lipid oxidation. A low respiratory quotient (R/Q) indicates reduced glu cose and increased lipid oxidation. The aim of this study was to determine if there is an association between substrate oxidation, using indirect calo rimetry, and other markers of malnutrition in patients with cirrhosis await ing liver transplantation. Methods: Indirect calorimetry (MedGraphics) was used to determine resting energy expenditure and R/Q after an overnight fas t. Anthropometric measurements including tricep skinfold thickness (TSF) an d midarm muscle circumference (MAMC) were performed and expressed as a perc entage of standard values. A 24-hour urinary creatinine excretion was colle cted to calculate creatinine height index (CHI) and serum albumin. A subjec tive global assessment (SGA) score was completed on each patient by a dieti tian and physician. Spearman rank correlation was used for statistical comp arison of R/Q to other nutritional markers. Results: Fifteen patients (7 me n, 8 women; mean age, 52 years) were studied. Mean values include: body mas s index (BMI) 27.7 kg/m(2) +/- 7.3, R/Q 0.78 +/- 0.04, serum albumin 2.97 g /dL +/- 0.56, TSF 71% +/- 27%, MAMC 85% +/- 13%, CHI 75% +/- 18%, and SGA m edian score A. There was a significant con-elation (p <.05) between R/Q and serum albumin, CHI, and SCA score. There was a greater than 90% correlatio n of SGA estimation by a physician and dietitian. Conclusions: There is goo d correlation between R/Q values and serum albumin, CHI, and SGA score. BMI and anthropometric measurements may suggest normal nutrition when, in fact , indirect calorimetry (R/Q) suggests changes consistent with abnormal fuel metabolism and poor nutrition. R/Q can be a useful adjunct in the nutritio n assessment of patients with hepatic cirrhosis.