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

Malnutrition in patients with hepatic cirrhosis is associated with abnormal fuel metabolism marked by reduced glucose oxidation and increased lipid oxidation. A low respiratory quotient (R/Q) indicates reduced glucose and increased lipid oxidation. The aim of this study was to determine if there is an association between substrate oxidation, using indirect calorimetry, and other markers of malnutrition in patients with cirrhosis awaiting liver transplantation.

Indirect calorimetry (MedGraphics) was used to determine resting energy expenditure and R/Q after an overnight fast. Anthropometric measurements including tricep skinfold thickness (TSF) and midarm muscle circumference (MAMC) were performed and expressed as a percentage of standard values. A 24-hour urinary creatinine excretion was collected to calculate creatinine height index (CHI) and serum albumin. A subjective global assessment (SGA) score was completed on each patient by a dietitian and physician. Spearman rank correlation was used for statistical comparison of R/Q to other nutritional markers.

Fifteen patients (7 men, 8 women; mean age, 52 years) were studied. Mean values include: body mass index (BMI) 27.7 kg/m2 +/- 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 median score A. There was a significant correlation (p < .05) between R/Q and serum albumin, CHI, and SGA score. There was a greater than 90% correlation of SGA estimation by a physician and dietitian.

There is good 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 nutrition assessment of patients with hepatic cirrhosis.