Decreased resting energy expenditure in non-dialysed chronic kidney disease patients

Non-dialysed chronic kidney disease (CKD) patients may have altered resting energy expenditure (REE) because of the important metabolic functions of the kidneys. The aim of the present study was to evaluate whether REE in clinically stable, non-diabetic and non-dialysed CKD patients with no clinical signs of inflammation, was different from that of gender and age pair-matched healthy controls. Subjects and methods. REE in 45 patients (20 male and 25 female; age 44.9 +/- 11.7 years; mean +/- SD) and 45 healthy individuals (20 male and 25 female; age 44.6 +/- 11.5 years) was measured by indirect calorimetry after a 12-h fast. In both groups, body composition was assessed by bioelectrical impedance. Glomerular filtration rate was assessed by creatinine clearance only in the CKD patients.

The mean creatinine clearance and serum creatinine of the CKD patients were 29.1 +/- 14.6 ml/min/1.73 m(2) and 3.48 +/- 2.48 mg/dl, respectively. Body fat (BF) and lean body mass (LBM) were similar between the two groups (CKD patients: BF 28.6 +/- 11.3%, LBM 46.9+/-10.0 kg; and healthy individuals: BF 28.1 +/- 7.54%, LBM 49.5 +/- 10.5 kg). REE of CKD patients was significantly lower than that of healthy individuals (1325 +/- 206 vs 1448 +/- 258 kcal/day; P = 0.01, respectively) even after adjusting for LBM by multiple regression analysis. In fact, the presence of chronic renal insufficiency reduced REE by 103.2 kcal/day (P = 0.02; 95% confidence interval (-15.9; 190.5)).

REE of clinically stable non-dialysed, non-diabetic patients in stages 2-5 of CKD was lower than that of age and gender pair-matched healthy individuals. Although the cause of reduced REE was unclear, it may be related to decreased food intake and to metabolic disturbances inherent with deterioration of renal function. Further studies will be necessary to clarify this issue.