[Reference values for vitamin B12 in blood in a population of children and one of adults using the IMxRB12 method].

Unlabelled: In this study we have performed the reference values of vitamin B12 of a population of 124 children aged 0-18 years and 42 adults aged 19-55 years, assessed by the recent method IMxR B12. Abbott. The population studied included outpatients, some inpatients and groups of subjects undergoing banal examinations in the Hospital Universitario Materno-Infantil of Barcelona.

Statistics: Data were first tested for goodness-of-fit gaussian distribution by a nonparametric test, by testing skewness and kurtosis coefficients for significance and by Kolmogorov-Smirnov test. The correlation with the age groups was evaluated with Student's-t-test.

Results: We show the histograms of the data obtained and a nonparametric approach selecting the central 95th percentile range. Reference limits (5-95th percentile range) were as follows: Premature infants = 365-1568 ng/L; 1-3 years = 345-1154 ng/L; 4-6 years = 330-1236 ng/L; 7-11 years = 312-1237 ng/L; 12-18 years = 328-1185 ng/L; Adults (19-55 years) = 300-964 ng/L. There were no significant differences between both sexes. The goodness-of-fit test for a gaussian distribution showed no departure from normality except for the groups of children 12-18 years old. A simple linear regression analysis showed that age significantly affected the concentration in inverse way.

Conclusions: The importance of establishing the reference values of vitamin B12 lies in the relevance of this serum analyte to some pathophysiological conditions. Considerable racial heterogeneity exists in populations, and these racial differences profoundly affect total values of vitamin B12 so that different racial reference limits have been suggested.