RESUMO
STUDY OBJECTIVE: To evaluate the association between involuntary weight loss and serum concentrations of tumor necrosis factor (TNF)-alpha 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-alpha were measured by using enzyme-linked immunosorbent assay. The TNF-alpha 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-alpha 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-alpha. Whether TNF-alpha 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-alpha can prevent or reverse involuntary weight loss and its associated morbidity and mortality.
