DETERMINATION OF INDIRECT REFERENCE INTERVALS AND VITAMIN B12 STATUS OF OUTPATIENTS IN ORDER TO RESPOND TO INQUIRIES FROM PRIMARY CARE PHYSICIANS.

Objectives: Vitamin B12 deficiency is still an important nutritional problem worldwide. There is no consensus on the Reference Intervals (RIs) for vitamin B12. In order to establish vitamin B12 RIs, we used the database of primary health care and estimated region specific intervals. Materials and Methods: Vitamin B12 results were collected from our laboratory information system between January 2014 and July 2014. We excluded the results of the individuals who have megaloblastic and microcytic anemia. After outliers detection and exclusion, we estimated the reference intervals of the "1-12, 13-18, 19-44, 45-64, and 65+" age-groups according to the IFCC Method. The statistical differences were examined between groups. Results: The reference limits and 90% confidence intervals (CIs) (n=14 748, 3790 male, ages: 1-96; 10958 female, ages: 1-115) were estimated as 97 (95-99) - 422 (420-424) pmol/L. The reference intervals with the 90%CIs were estimated as 127 (117-144) - 570 (521- 599) and 96 (94-98) - 418 (418-422) pmol/L for 1-12 age-group (n=345) and for 13+ age group (n=14 403), respectively. Conclusion: Both the lower and upper limits of the estimated reference intervals were found lower than the reference limits recommended by the manufacturer. Our findings revealed that the RIs of vitamin B12 should be given for 1-12 and 13+ age groups separately. The big data obtained from laboratories should be used for determination of its population health status. Since our population is composed of the outpatients, the estimated VitB12 reference intervals may establish basic information for examination of our population for the VitB12 deficiency. [ABSTRACT FROM AUTHOR]