How much does body mass index affect serum carcinoembryonic antigen concentration?

BACKGROUND As the effect of obesity on serum carcinoembryonic antigen (CEA) concentration and mass is uncertain, we designed the study in context of Chinese healthy males with no clinical evidence of any cancer. METHODS Of note, 1,915 healthy males were retrospectively collected, with ages ranging from 18 to 84 years. Two equations, a body surface area (BSA)-based and a hematocrit-based, were applied, respectively, for plasma volume and CEA mass calculation. Multivariate linear and logistic regression models were used to detect the associations of CEA concentration, and the two estimates of CEA mass with body mass index (BMI); possible confounding factors, including age, leucocyte count, and smoking status, were adjusted. RESULTS CEA concentration significantly decreased with increasing BMI (P < 0.001); however, CEA mass remained consistent or increased by using the BSA- or hematocrit-based equation. A screening level of CEA 5.0 ng/mL in normal-weight men was found to correspond to 4.52 ng/mL in overweight and obese men. CONCLUSIONS CEA may be affected in obese individuals by several factors, including but not limiting to hemodilution, inflammatory conditions, and insulin resistance. The relationship between CEA concentration and BMI might be highly dependent on which factor or factors have been predominant. IMPACT The BMI status of participants should be taken into account during assessment of serum CEA levels in healthy males.