25-Hydroxyvitamin D3-[D3]

25-Hydroxyvitamin D3, also known as 25(OH)D3 or calcidiol, is a vitamin D metabolite that plays an essential role in the regulation of calcium and phosphorus metabolism. It is produced in the liver by the hydroxylation of vitamin D3 (cholecalciferol) and is considered the most reliable indicator of vitamin D status in humans. 25(OH)D3 is commonly used as a biomarker for vitamin D deficiency or insufficiency. It is also used in the diagnosis and management of various bone and mineral disorders, such as osteoporosis, rickets, and hypophosphatemia. Chemically, 25(OH)D3 is a secosteroid hormone that binds to vitamin D receptors (VDRs) in a variety of tissues, including bone, intestine, kidney, and immune cells. Its biological activity is mediated through the conversion to the active metabolite, 1,25-dihydroxyvitamin D3 (calcitriol), which regulates gene expression and cellular differentiation. The recommended level of 25(OH)D3 in the bloodstream varies by age, sex, and health status. Generally, a level of 30 ng/mL or higher is considered sufficient, while levels below 20 ng/mL are indicative of deficiency. Vitamin D supplementation is commonly recommended to individuals with low levels of 25(OH)D3, although the optimal dose and duration of treatment may vary depending on the individual's needs and health status.