Objective: To investigate the potential roles of leptin and ghrelin in malnutrition in patients with chronic obstructive pulmonary disease (COPD).
Methods: Plasma leptin, total ghrelin and active ghrelin, TNF-alpha and IL-6 levels were determined in 53 patients with COPD and 26 control subjects. Body compositions were assessed by bioelectrical impedance analysis.
Results: Plasma leptin levels were significantly lower in underweight patients than those in normal weight patients and in healthy controls [2.6 (2.0 - 4.4) vs. 6.1 (5.1 - 7.8) vs. 4.8 (3.3 - 6.1) ng/L]. The leptin level was associated positively with fat mass (r = 0.662, P = 0.000) and TNF-alpha (r = 0.431, P = 0.001) in the patients. By a stepwise multiple regression analysis, fat mass, TNF-alpha, presence of COPD, smoking and sex were found to affect leptin level (R(2) = 0.635). Both plasma total ghrelin levels and active ghrelin levels were significantly higher in underweight patients than those in normal weight patients and in healthy controls [total ghrelin: 1090 (860 - 2838) vs. 765 (651 - 941) vs. 844 (676 - 1045) ng/L; active ghrelin: 63 (50 - 97) vs. 47 (41 - 56) vs. 54 (41 - 60) ng/L]. Plasma total ghrelin and active ghrelin were associated negatively with BMI respectively (total ghrelin: r = -0.517, P = 0.000; active ghrelin: r = -0.417, P = 0.002).
Conclusions: Plasma leptin levels were decreased, while plasma total ghrelin and active ghrelin levels were elevated in underweight patients with COPD, and the levels were associated with nutritional parameters. The plasma levels of leptin and ghrelin may be a compensatory mechanism in malnutritional status of COPD. After adjustment for nutritional parameters, leptin levels were elevated in COPD patients and correlated to TNF-alpha. The result suggests that leptin may play a role in systemic inflammation of COPD.