If you are suddenly feeling pain in bones and muscle without too much strenuous activity, you should go for a vitamin D3 test. Vitamin D3 is Cholecalciferol which is the more active form of vitamin D. The test is also known as Cholecalciferol test. The Cholecalciferol converts into Calcidiol in liver and calcidiol convert into the Calcitriol hormone. The test measures levels of activated vitamin D or Caitriol in blood. Your doctor will specifically order vitamin D3 blood test to confirm Vitamin D deficiency in one’s body or monitoring effectiveness of treatment. The level of Vitamin D3 does not depend on gender and age.