[Selenium in serum and plasma: epidemiology and reference values].

OBJECTIVE: To review and analyze the literature on selenium (Se) levels in human serum and plasma; to describe some variations; to obtain reference values for the countries of Europe and Latin America, and to provide an information framework for future studies on the subject.
METHODS: Scientific literature was reviewed to gather information on selenium serum or plasma levels in people identified as "healthy." The LILACS, SciELO, and PubMed Medline databases were consulted. The search for information could be from any date (up to January 2010) and in any language. Weighted arithmetic means and standard deviations were calculated.
RESULTS: For Europe, 161 reports published between 1972 and 2009 were found, covering 49,869 healthy adults, 28 countries, and 8 regions. Serum/plasma Se levels ranged from 48.2 to 124.00 µg/L. Weighted values for Europe were 85.19±14.58 (CI 95% for the weighted average, 85.124-85.256). The averages by country, region, and measurement technique were statistically different, with significant differences associated with sex and age. Twenty-three of the studies involved individuals under 19 years of age in 10 European countries. The weighted values for this population were 74.21±9.50 µg/L (CI 95%, 73.95-74.46). Only 11 studies from Latin America were available. Serum/plasma Se was 91.51±18.78 Ìg/L in adults; 93.25±39.20 in children under 15; and 130±30 in newborns less than 25 hours old.
CONCLUSIONS: Se serum/plasma levels in Europe showed statistically significant differences by sex and age. Se levels were higher in Latin American adults and children than in Europeans, but the Latin American data are based on few people. The technique for measuring Se in serum/plasma appears to have a significant influence. Properly planned and designed population studies should be conducted in Latin America in order to establish regional reference values for Se in serum and plasma.