SubscribeVitamin D is crucial to the overall health and well being of humans and animals, having important functions in calcium homeostasis and bone metabolism.
Sunlight exposure to skin may provide adequate levels of vitamin D; however, there are numerous reports of vitamin D insufficiency or deficiency. 25-OH D is regarded as the best measurement of overall vitamin D status.
1,25-dihydroxyvitamin is the most biologically active vitamin D metabolite. 25-OH D has higher affinity for Vitamin D binding protein (VDBP) than 1,25 dihydroxyvitamin D; whereas, 1,25 dihydroxyvitamin D has higher affinity for the vitamin D receptor (VDR) than does 25-hydroxy vitamin D.
HPLC and immunoassays allow the determination of vitamin D status, as measured by 25-OH D, and 1,25 (OH)2D. Future studies will determine the amount of vitamin D necessary for optimal health and well-being.