Low circulating leptin levels in protein-energy malnourished chronically ill elderly patients

Objective. To evaluate serum leptin, a fat cell-derived protein, levels in relation to the malnutrition often observed in chronic disease. Design. A comparison of circulating leptin concentrations in malnourished chronically ill elderly and in age-matched controls. Setting. A university-affiliated teaching hospital in Stockholm, Sweden. Subjects. Nineteen protein-energy malnourished elderly patients (74 +/- 1 years) with various chronic nonmalignant diseases and 18 healthy controls (72 +/- 1 years). Main outcome measures. Serum leptin levels measured by radioimmunoassay technique, nutritional status as expressed by body mass index (kg m(-2)), triceps skin fold, arm muscle circumference and serum albumin, and serum orosomucoid concentrations indicating inflammatory status. Results. Patients and controls displayed body mass indexes of 17.4 +/- 0.7 and 25.0 +/- 1.1 (P < 0.001), respectively. Triceps skin fold (TSF) measurements revealed a pronounced fat depletion in the patients, being 8.5 +/- 0.9 and 22.3 +/- 1.5 mm (P < 0.001) in female and 6.1 +/- 0.7 and 10.8 +/- 0.8 mm (P < 0.001) in male patients and controls, respectively. Patient serum leptin concentrations were less than half of the corresponding concentrations in the controls, 4.3 +/- 1.1 and 9.3 +/- 1.3 ng mL(-1) (P < 0.01), respectively. The highest leptin concentrations were registered in female controls, 12.1 +/- 1.6 ng mL(-1). The serum leptin levels in the controls correlated with TSF (r = 0.74; P < 0.001). No such correlation was found in the patients. Conclusions. Serum leptin levers were low and did not seem to be directly associated with fat and muscle depletion in elderly patients with chronic illness, whereas they appeared to be positively correlated to body fat in healthy elderly.