Marker of vitamin D status in healthy children: Free or total 25-hydroxyvitamin D?

Objective: To assess if serum free 25-hydroxyvitamin D (25OHD) is a better indicator of vitamin D status than total 25OHD in healthy children.

Methods: Cross-sectional prospective clinical study was designed. We measured serum free 25OHD concentrations and its correlation with calculated free 25OHD, total 25OHD, intact parathyroid hormone (PTH), and vitamin D binding protein (DBP) in children.