Lack in vitamin D reduces the absorvtion of calcium in the body, accelerates bone loss and may increase the risk of fractures due to osteoporosis. Vitamin D can be ingested by foods and specific supplements, but the main source for the vitamin is synthesis in the skin by usin sun radiation. Today, quanitification of vitamin D levels is performed using a blood test. Mostly; the physician will send the patient to check the levels and vitamin D if he suffers from osteoporosis, renal inpairment, suspected for activity of the thyroid gland; tubeculosis or sacoidosis.