Vitamin D: a 14-year retrospective study at a clinical laboratory in Brazil

This study aimed to assess vitamin D (25OHD) levels in individuals who underwent an examination at a private laboratory (between latitudes 14° and 22° south) over 14 years, stratified by sex, age, and epidemiological profiles, and determine variations in the number of tests performed over the years.

All records of 25OHD tests performed at a private clinical laboratory in Brazil were analyzed. This retrospective cross-sectional study included patients stratified by sex (female or male), age range (0-17, 18-40, 41-59, and ≥ 60 years), and year of testing. The final sample size was 193,725 patients. Categorical variables are presented as absolute and relative frequencies and numerical variables as means ± standard deviation. Comparisons between groups were performed using the equality of proportions test.

The number of tests performed steeply increased since 2010. More tests were performed in female individuals (73.3%) and individuals aged 41-59 years (32.2%). Most samples (68.0%) demonstrated sufficient vitamin D status. Women had a higher incidence of vitamin D deficiency than men (33.1% and 26.6%, respectively; p < 0.001). Individuals aged ≥ 60 years had the highest incidence of vitamin D deficiency (68.4%), while individuals aged 0-17 years had the lowest (32.2%) (p < 0.001).

Despite increased testing and attention given to vitamin D in recent years, our study demonstrates high levels of deficiency in a country with geographical conditions favorable to its production.