Ghrelin is an important orexigenic hormone that reduces fat oxidation and increases adiposity. This study investigated plasma ghrelin levels in Chinese Uygur patients with chronic obstructive pulmonary disease (COPD). Plasma ghrelin and anabolic and catabolic factors were measured in 38 patients and 24 control subjects. COPD patients were divided into two groups based on body mass index (BMI): underweight (BMI < 20 kg/m(2), n = 18) or normoweight (BMI > or = 20 kg/m(2), n = 20). Plasma ghrelin levels were found to be significantly higher in underweight than in normoweight patients or healthy controls. Circulating tumour necrosis factor-alpha and interleukin-6 concentrations were significantly higher in underweight than in normoweight patients, whereas insulin concentrations were significantly lower. Plasma ghrelin levels correlated negatively with forced expiratory volume in 1 s (FEV(1); r = 0.35), but did not significantly correlate with FEV(1)/forced vital capacity. Plasma ghrelin levels were elevated in underweight COPD patients and were associated with cachexia and abnormal pulmonary function.