Vitamin D, also known as “calciferol,” is a fat-soluble vitamin that we can get from sunlight, certain foods, and supplements. The Vitamin D from these sources isn’t active right away; it needs to go through two steps in the body to be usable. First, it is changed in the liver into a substance called 25-hydroxyvitamin D, or “calcidiol.” Then, in the kidneys, it’s converted into the active form of vitamin D called 1,25-dihydroxyvitamin D, or “calcitriol.” Vitamin D helps your body absorb important minerals, like calcium and phosphate, from your diet, which is necessary to keep the right levels of these nutrients in your body. It’s important to note that sunlight can only help produce Vitamin D if there’s already enough Vitamin D in your body. The best way to measure how much Vitamin D you have is by looking at the level of 25(OH)D in your blood. This reflects the Vitamin D you’ve made in your body from sun exposure as well as what you’ve taken in through food and supplements. Vitamin D is responsible for nurturing our teeth and bones. It is also very important for our muscles, nerves and immune system to work properly and effectively. It is a vital nutrient for everyone. This test is performed to check the levels of Vitamin D in your body to balance the nutrient and to help in diagnosing any conditions in case of Vitamin D deficiency.