Abbreviations:
CLIA, chemiluminescence immunoassays
HPLC, high-performance liquid chromatography
F, female
M, male
25(OH)D, 25 hydroxyvitamin D levels
Funding: This study did not receive any specific grants from any funding agencies in the public, commercial, or not-for-profit sector.
Conflict of interest: The authors declare that they have no conflict of interest.