Vitamin B12 Active Blood Test

The Vitamin B12 Active (Holotranscobalamin) blood test measures the level of active vitamin B12 available for your body to use. Unlike standard total B12 tests, which include inactive forms that the body cannot absorb, this test specifically checks the biologically active fraction—holotranscobalamin—providing a more accurate assessment of your functional B12 status.

This test helps identify early or hidden vitamin B12 deficiency, even when total B12 levels appear normal. Vitamin B12 is essential for energy production, nerve function, red blood cell formation, and brain health. Low active B12 levels may contribute to fatigue, memory issues, mood changes, and neurological symptoms.