Carcinoembryonic antigen (CEA) in blood in cases of pneumonia.

Serum levels of carcinoembryonic antigen (CEA) were analysed in patients with pneumonia of different etiology. Significant (p less than 0.01) increases in blood CEA levels occurred in all groups of pneumonia of bacterial etiology, i.e., pneumococcal, gram-negative or chlamydial. In viral pneumonia similar increases were observed, but the changes were not statistically significant, probably due to the small number of patients. In pneumonia of unknown etiology CEA behaved as in bacterial pneumonias. Maximal values between 5 and 15 micrograms/l CEA were common in pneumonia, the basal level usually being less than 5 micrograms/l. The severity of pneumonia, as judged by maximal erythrocyte sedimentation rate, correlated weakly with CEA levels in the bacterial group (p less than 0.05). In pneumonias of unknown etiology white blood cell counts and C-reactive protein levels correlated significantly with maximal CEA (p less than 0.01). In conclusion we have demonstrated, that in pneumonias of different etiology strongly but transiently increased blood CEA levels are the rule. The severity of pneumonia is not clearly correlated with CEA levels.