Objective: In this study we aimed to calculate the reference intervals of carbohydrate antigen 15-3 (CA15-3), carbohydrate antigen 19-9 (CA19-9), carbohydrate antigen 125 (CA125) and carsinoembriyogenic antigen (CEA).

Materials and Methods: 325 healthy individuals admitted to our hospital's outpatient units between 17.08.2009 - 11.09.2009 were included in the study according to Clinical and Laboratory Standarts Institute, CLSI Approved Guideline C28-A. Serum levels of CA 15-3, CA19-9, CA125 and CEA were analyzed using Immulite 2000 System (Healthcare Diagnostics Products Ltd. England), a two-site chemiluminescent enzyme immunometric assay.

Results: The mean CA 15-3 level was 22.32 ± 13.45 U/mL, mean CA19-9 level was 8.95 ± 9.10 U/mL, mean CA125 level was 7.97 ± 4.62 U/mL, mean CEA level was 2.45 ± 1.74 ng/mL. CA15-3 reference intervals were found as 8.33- 52.47 U/mL, CA19-9 reference intervals were found as 2.5-32.35 U/mL, CA125 reference intervals were found as 2.28-19.15 U/mL, CEA reference intervals were found as 0.36-6.09 ng/mL for < 50 years of age and 1.01-8.72 ng/mL for > 50 years of age.

Conclusion: The reference values found in our study were different from the values recommended by the manufacturer. We think that these values reflect our population more truly than manufacturers and should be used as reference intervals.