Elevation of tumor necrosis factor in head injury.

Tumor necrosis factor (TNF) is a cytokine which mediates protein wasting in pathological states by promoting the catabolism of visceral tissues and skeletal muscle. The role that TNF plays in nitrogen wasting following head injury was studied by measuring TNF in the serum of 21 patients with severe head injury. Parallel measurements of TNF and urinary nitrogen excretion were performed on days 1, 3, and 5 after head injury. TNF values after head injury ranged from 65 pg/ml to 7500 pg/ml, with a mean of 1147 pg/ml, compared to control values of serum TNF of less than 38 pg/ml. The mean daily urinary nitrogen loss was 13 g/day with a range of 2.8 to 27.6 g/day, and the mean nitrogen balance was -5.8 g with a range of +4.6 to -19.1 g. While both serum TNF levels and nitrogen loss were increased after head injury, the elevation of TNF did not correlate strongly with nitrogen wasting.