PLASMA LEPTIN CONCENTRATIONS AND ENERGY-EXPENDITURE IN HEART-FAILURE PATIENTS

Leptin, the protein encoded by the obese gene, is a newly described ho rmone implicated in the regulation of energy balance. To examine the p ossible role of leptin in the energy dysregulation that frequently acc ompanies chronic heart failure, we examined plasma leptin concentratio ns and energy expenditure in 18 heart failure patients (aged 71 +/- 6 years) and 46 healthy elderly controls (66 +/- 6 years). Plasma leptin concentrations were measured by radioimmunoassay, daily energy expend iture by doubly labeled water, and body composition by dual-energy x-r ay absorptiometry. Fat mass was lower (P < .01) in heart failure patie nts compared with healthy controls, whereas fat-free mass did not diff er between groups. Plasma leptin concentrations were not different bet ween heart failure patients and healthy controls (5.1 +/- 4.2 v 6.8 +/ - 4.4 pg/mL) and remained similar after statistical control for fat ma ss (6.0 +/- 3.1 v 7.1 +/- 3.2 pg/mL). Plasma leptin was related to fat mass in heart failure patients (r = .92, P < .01) and healthy control s (r = .69, P < .01). Free-living daily and physical-activity energy e xpenditures were lower (P < .01) in heart failure patients compared wi th healthy controls. Plasma leptin concentrations were related to both daily (r = .67, P < .01) and resting (r = .67, P < .01) energy expend iture in heart failure patients, but not in healthy controls (r = .09 and r = .33, respectively). In conclusion, we found an association bet ween plasma leptin concentrations and energy expenditure in heart fail ure patients, but not in healthy controls. Thus, leptin may participat e in the regulation of energy expenditure and body energy stores in he art failure patients. Copyright (C) 1997 by W.B. Saunders Company.