Determination of indirect reference intervals of vitamin B12 for outpatients admitted to primary healthcare centers

Abstract

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 obtained from a primary healthcare organization and estimated region-specific intervals. Vitamin B12 results were collected from our laboratory information system (LIS) between January 2014 and July 2014. We excluded the results of the individuals who had megaloblastic and microcytic anemia. After outlier detection and exclusion, we estimated the RIs of the "1-12, 13-18, 19-64 and 65 +" age groups according to the International Federation of Clinical Chemistry (IFCC) method. Statistical differences were examined between groups. The reference limits and 90% confidence intervals (CIs) (n = 14,748, 3790 male, age: 1-96; 10,958 female, age: 1-115) were estimated with 90% CIs as 106 (104-107)-393 (391-395) pmol/L. We also estimated the reference limits of the "1-12, 13-18, 19-64 and 65 +" age groups to be 127-459, 108-398, 106-384 and 104-426 pmol/L, respectively. There was no difference between genders in all age groups. Both the lower and upper limits of the estimated RIs were found to be lower than the reference limits recommended by the manufacturer. Our findings revealed that the RIs of vitamin B12 should be given for the "1-12, 13-18, 19-64 and 65 +" age groups separately. The big data obtained from laboratories should be used for the determination of its population health status. As our population is composed of outpatients, the estimated vitamin B12 RIs may establish the basic information for the examination of our population for vitamin B12 deficiency. © 2020 Esin Avci et al., published by De Gruyter, Berlin/Boston.