Serum concentrations of interleukin-6, tumour necrosis factor-alpha, and C-reactive protein in patients undergoing major operations

Abstract

Objective: To investigate the kinetics of interleukin-6 (IL-6), tumour necrosis factor-alpha (TNF-alpha) and C-reactive protein after a surgical operation.

Design: Prospective study.

Setting: Teaching hospital, Sweden.

Subjects: 28 patients undergoing cardiac operations, joint replacement, or gastric restrictive operations.

Interventions: Samples of serum were taken before operation; at 0, 6, and 12 hours; and then daily for six days.

Outcome measures: IL-6, TNF-alpha, and C-reactive protein concentrations at specified time points, and their correlation with complications and outcome.

Results: The IL-6 concentration peaked soon after operation, and that of C-reactive protein 48-96 hours later. Serum IL-6 concentrations were highest in the eight patients undergoing cardiac operations. In one patient an infective complication occurred resulting in secondary peaks of IL-6 and C-reactive protein. Three patients who developed postoperative circulatory and respiratory instability had no additional changes in cytokine concentrations. The overall concentrations of IL-6 were raised above 100 pg/ml for a mean of 36 hours after operation and those of C-reactive protein were over 100 mg/l for a mean of 106 hours (p < 0.0001). Serum TNF-alpha concentrations were low in all patients.

Conclusion: The maximum serum concentrations of IL-6 and C-reactive protein after surgical operations were comparable to those in patients with sepsis. If IL-6 and C-reactive protein analyses are used in the diagnosis of infective complications, evaluation of the results should be related to the length of time between the operation and sampling, and to the clinical findings. The shorter period during which IL-6 was raised compared with C-reactive protein indicates that IL-6 may be a more useful marker of postoperative infective complications.