Vitamin D is a vital element which maintains strong bones and helps the body to absorb calcium throughout the entire life. Vitamin D is obtained from various sources like eggs, fish, dairy products or suns UV rays. Vitamin D passes through several processes in the body. The first transformation occurs in the life where the body converts it to a chemical known as Hydroxyvitamin D. The Vitamin D 25-Hydroxy total test is the best test to monitor the level of vitamin D in the blood. The test determines whether the body possesses the high or low level of vitamin D. The test is also an important indicator of rickets and osteoporosis.