This is a specialized test that measures the specific D3 form (cholecalciferol) in your blood, often to monitor the effectiveness of D3-only supplementation. However, for a complete, comprehensive, and accurate assessment of your body's overall Vitamin D status, the test you are almost certainly looking for is the Vitamin D Total (25-hydroxy) test. The 'Total' test is the gold-standard, foundational screening that reflects your body's vitamin D reserves from all sources (sun, food, and supplements), providing the most actionable data for your health.