This test determines the level of vitamin D in the body and is recommended when disorders related to bone health and homeostasis of calcium are present. It gives the full picture of bone health and used for the diagnosis of rickets, frequent fractures, softness and weakness of bones. The active form of this vitamin (1, 25-D) directly plays crucial role in the absorption of calcium from the intestine. Deficiency of this vitamin causes severe bone weakness and deformation. Number of other diseases also relate to abnormalities in vitamin D levels and thus this test is also used in the diagnosis of heart diseases, multiple sclerosis and different types of cancers.