Tumor necrosis factor-α and involuntary weight loss in elderly, community-dwelling adults

Abstract

Study Objective. To evaluate the association between involuntary weight loss and serum concentrations of tumor necrosis factor (TNF)-α in elderly, community-dwelling adults. Design. Cross-sectional, single-time point investigation. Setting. Two primary care ambulatory clinics. Subjects. Ambulatory adults aged 70 years or older with involuntary weight loss of 2.27 kg (5 lbs) or more, or with stable weight (± 0.91 kg [2 lbs]) for the 3 months before enrollment. Measurements and Main Results. Ten subjects with weight loss (mean ± SD -4.9 ± 2.6 kg) and 25 subjects with stable weight (+ 0.06 ± 0.55 kg) were enrolled. The latter group was recruited to serve as a comparison group to the weight-loss group. Subjects donated a venous blood sample and were administered the Mini Nutritional Assessment at a single clinic visit. Serum concentrations of TNF-α were measured by using enzyme-linked immunosorbent assay. The TNF-α concentrations were significantly higher in subjects with weight loss (mean ± SD 19.3 ± 24.9 pg/ml) than in subjects with stable weight (mean ± SD 1.1 ± 2.0 pg/ml, p<0.01). No relationship was found between the TNF-α concentration and the degree of weight loss expressed as a percentage of total body weight. Conclusion. Older adults with involuntary weight loss had increased circulating concentrations of TNF-α. Whether TNF-α plays a causal role in involuntary weight loss among older adults is unclear; however, this finding is consistent with those in other disease states associated with cachexia. Further research is necessary to clarify this relationship and to determine if pharmacotherapeutic interventions targeted at TNF-α can prevent or reverse involuntary weight loss and its associated morbidity and mortality.