Serum lysozyme in Crohn's disease. A useful index of disease activity.

Serum lysozyme concentrations were determined in patients with clinically active and inactive Crohn's disease as well as in healthy volunteers. The mean serum lysozyme concentrations (+/- SE) for each group were as follows: controls, 8.8 +/- 0.4; active Crohn's disease, 20.8 +/- 0.8; and inactive Crohn's disease, 10.4 +/- 0.7 mug per ml. The mean lysozyme level was significantly greater in active Crohn's disease as compared to normal subjects (P less than 0.001) and patients with inactive disease (P less than 0.001). Moreover, in patients with clinically severe Crohn's disease there seems to be a trend toward greater lysozyme levels, as opposed to those with mild to moderately active disease. In patients followed serially during the course of their disease, serum lysozyme levels increased with exacerbations of the illness and decreased with clinical improvement. These findings suggest that the serum lysozyme concentrations may serve as a useful index of the activity of Crohn's disease and aid in monitoring the clinical course of such patients.