Vitamin D is responsible for the absorption of calcium, magnesium and phosphate by your body. Consequently, it is responsible for healthy bones and teeth. It is a fat-soluble secosteroid. Since one of its major sources is sunlight, it is often referred as the "sunshine vitamin". There are two types of Vitamin D: Vitamin D2 and Vitamin D3. It is Vitamin D3 that you naturally get from the sunlight.
You get Vitamin D2 from different food sources such as eggs, certain seafoods, butter, oily fish, and fish oil. Vitamin D Test is done to measure the level of 25(OH)D in your blood, which stands for 25 hydroxyvitamin D, which is formed with a combination of Vitamin D2 and Vitamin D3. You need a Vitamin D test if you are showing symptoms of Vitamin D deficiency that may include pain in the joints, bone weakness or bone softness, bone malformation (especially among children) and easily caused fractures.