Resting energy expenditure of chronic kidney disease patients: Influence of renal function and subclinical inflammation

Background: The resting energy expenditure (REE) of patients with chronic kidney disease (CKD) might be influenced by the degree of renal function and by a subclinical inflammatory condition. The aim of this study is to evaluate the impact of these 2 variables on the REE of patients with CKD. Methods: A cross-sectional study was performed on 91 nondialyzed and nondiabetic patients with CKD with no clinical signs of inflammation. Patients were divided into quartiles of creatinine clearance (CrCl) and tertiles of C-reactive protein (CRP) level. REE was measured by means of indirect calorimetry, and the presence of a subclinical inflammatory condition was assessed by means of serum CRP concentration. Results: CrCl interquartile ranges calculated were: quartile 1 (CrCl :5 18 mL/min [less than or equal to0.30 mL/s]; n = 24); quartile 2 (CrCl, 19 to 29 mL/min [0.31 to 0.48 mL/s]; n = 22); quartile 3 (CrCl, 30 to 42 mL/min [0.49 to 0.70 mL/s]; n = 23), and quartile 4 (CrCl greater than or equal to 43 mL/min [greater than or equal to0.71 mL/s]; n = 22). Nonadjusted REE and REE adjusted for sex, age, and lean body mass did not differ among the 4 CrCl quartiles. The following ranges were calculated for CRP tertiles: tertile 1 (CRP less than or equal to 0.14 mg/dL; n = 30), tertile 2 (CRP, 0.15 to 0.49 mg/dL; n = 31), and tertile 3 (CRP greater than or equal to 0.50 mg/dL; n = 30). The nonadjusted REE in CRP tertile 3 was significantly greater than those in tertiles 1 and 2. REE adjusted for sex, age, and lean body mass was greater in CRP tertile 3 than tertile 1, a difference equivalent to 123.7 kcal/d (P = 0.003; 95% confidence interval, 42.9 to 204.5). A borderline difference was observed between CRP tertiles 3 and 2. When analyzing the entire group, REE did not correlate with either serum creatinine level or CrCl, and a borderline correlation between REE and log of CRP was observed (r = 0.19; P = 0.07). Conclusion: This study suggests that REE is not influenced by degree of renal function, but it may be elevated during a condition of subclinical inflammation.