Seasonal Variations in Serum Levels of 25‐Hydroxyvitamin D and Parathyroid Hormone but no Detectable Change in Femoral Neck Bone Density in an Older Population with Regular Outdoor Exposure

Abstract

The seasonal changes in serum levels of 25OHD, PTH, and ionized calcium and the positive correlation between femoral neck BMD and 25OHD indicate that regular outdoor daylight exposure during the summer could enhance calcium homeostasis and possibly bone health, even among very old people living at northerly latitudes.