Mining the Age-Dependent Reference Intervals of B Vitamins from Routine Laboratory Test Results

OBJECTIVE: To describe the reference intervals of folate, vitamin B12, vitamin B6, and vitamin B1 by sex and age. METHODS: The study was performed by gathering data on 55,811 subjects from 57 medical centers. Groups were categorized based on age and grouped according to statistical significance values. The reference values for the different groups were determined using the Bhattacharya and Hoffmann methods. RESULTS: Vitamin B1 and B6 values and folate (vitamin B9) levels between the sexes were statistically significantly increased in the group aged 0 to 10 years. Likewise, we witnessed a similar increase in vitamin B12 levels in the group aged 0 to 5 years. However, low vitamin B6 levels (P <.001) were detected in nongeriatric patients (aged 0-60 years), and the reference intervals (3.4-41.9 µg/L) also were significantly different from those in the geriatric group (aged 61-100 years; 2.0-29.4 µg/L). CONCLUSION: A lower vitamin B6 reference limit allows detection of subclinical vitamin deficiency more precisely in the geriatric group; respective reference intervals should be revised accordingly.