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

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.