Vitamin D deficiency in the elderly in Athens, Greece.

Vitamin D deficiency characterized by low 25-hydroxyvitamin D [25(OH)D] levels has been found to be prevalent among the elderly in many regions of the world. To investigate the vitamin status in elderly community-living persons in Athens, we measured 25(OH)D and parathyroid hormone (PTH) in elderly persons and young blood donors during the winter and summer. The changes in these parameters in a subgroup of the elderly were studied longitudinally.