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

Abstract

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