Mean 25-hydroxyvitamin D (25(OH)D)) values and characteristics of the twins as a function of season. SnellmanGreta MelhusHåkan GedeborgRolf BybergLiisa BerglundLars WernrothLisa MichaëlssonKarl 2013 <p>Mean 25-hydroxyvitamin D levels are adjusted for the twin-ship dependence.</p><p>*Results are based on the 40 (20%) participants who had measurable levels of 25-hydroxyvitamin D<sub>2</sub>.</p>