Total, bioavailable and free 25-hydroxyvitamin D levels as functional indicators for bone parameters in healthy children.

In healthy children, total, bioavailable, and free 25OHD levels comparably reflected lifestyle factors. In normal-weight children, the con-25OHDBioA and con-25OHDFree, but not m-25OHDFree levels, reflected bone mass, as did the 25OHDTotal level.