A Vitamin D Advanced (D2, D3 & D Total) blood test measures the levels of various forms of 25-hydroxy Vitamin D (25-OH D2, 25-OH D3, and D Total) in the body. This test serves as a valuable indicator for conditions such as osteoporosis (bone weakness), rickets (bone malformation), and osteomalacia (bone softening). Additionally, it aids in diagnosing and monitoring the functioning of the parathyroid gland, which is essential for vitamin D metabolism due to the parathyroid hormone (PTH).
Vitamin D, a fat-soluble essential nutrient, exists in two primary forms: Vitamin D3 (Cholecalciferol), derived from animal sources, and Vitamin D2 (Ergocalciferol), derived from plant sources. Both perform similar functions. The main sources of Vitamin D3 are certain foods, dietary supplements, and exposure to ultraviolet B (UVB) radiation from sunlight, while Vitamin D2 comes from plant-origin products, supplements, and mushrooms. In the liver, both forms are converted into 25-hydroxy D2 or D3, respectively. The levels of 25-hydroxy Vitamin D in the blood are considered the best parameter for assessing the body's vitamin D status.
According to a study by the National Center for Biotechnology Information (NCBI), vitamin D deficiency is highly prevalent across all age groups in India. Low vitamin D levels can lead to numerous disorders, such as an increased risk of fractures, muscle weakness, lethargy, immune system dysfunction, and a higher risk of chronic diseases like diabetes. A Vitamin D Advanced (D2, D3 & D Total) test can help identify vitamin D deficiency and, in some cases, determine if there is an excess of vitamin D in the body (often due to excessive supplements).
The Vitamin D Advanced (D2, D3 & D Total) test provides a more detailed assessment of vitamin D status by evaluating Total 25-OH D as well as 25-OH metabolites of vitamin D2 and vitamin D3 using the highly specialized LC-MS/MS technique. In contrast, a routine Vitamin D (25-OH) test measures only the Total 25-OH D (D2+D3) and does not differentiate between the two forms. Measuring vitamin D by the LC-MS/MS method is considered the gold standard for vitamin D evaluation, as it is a highly specialized and sensitive method capable of differentiating between various forms of vitamin D, 25 (OH) D, and their substrates, D2 and D3. Moreover, LC-MS/MS can detect very small amounts of vitamin D and its byproducts.