Elevated carcinoembryonic antigen in patients with COVID-19 pneumonia

Coronavirus disease 2019 (COVID-19) tends to affect multiple organs and induce abnormal laboratory parameters. We designed this study to investigate the association between carcinoembryonic antigen (CEA) elevation and SARS-CoV-2 infection.

We retrospectively analyzed 177 patients with confirmed SARS-CoV-2 infection who received plasma CEA assays during hospitalization. Patients with other causes of CEA elevation were excluded. Data regarding epidemiological and demographical characteristics, clinical symptoms, laboratory tests, and outcomes were analyzed. Linear regression analysis was used to evaluate the correlation between CEA levels and inflammation severity.

171 patients were included in the final study and 32 patients (18.7%) had raised serum of CEA (> 5 ng/ml), with a median (range) age of 66 (53-86). The median [interquartile range (IQR)] CEA level was 11.4 ng/ml (8.1-21.6), which was significantly higher than the upper limit of reference range. CEA level between 5-10 ng/ml was in 11 patients, 10-15 ng/ml in 10 patients, and > 15 ng/ml in 11 patients. No correlation was found between CEA levels and lymphocyte (R² = 0.055; P = 0.10) nor CRP (R² = 0.026; P = 0.38). The median levels of CEA were 20.0 ng/ml (IQR, 14.7-23.0) in non-survivors and 10.9 ng/ml (IQR 7.5-16.1) in survivors, and the difference between two groups was statistically significant (P = 0.048).

SARS-CoV-2 infection might be another cause of CEA elevation, with nearly 20% of patients experienced transient and marked CEA increment during COVID-19 pneumonia. The false-positive results of CEA elevation might have clinical significance for patients with colorectal cancer.