ACTIVE VITAMIN B12 (HOLOTRANSCOBALAMIN)

This test measures the active form of vitamin B12 in the blood, known as holotranscobalamin (holoTC). Vitamin B12 is essential for nerve function, red blood cell production, and DNA synthesis. HoloTC is considered the earliest marker of vitamin B12 deficiency because it reflects the amount of B12 available for cellular uptake. Low levels of holoTC can indicate vitamin B12 deficiency even before clinical symptoms appear. This test is particularly useful for diagnosing and monitoring vitamin B12 deficiency, which can lead to conditions such as pernicious anemia and neurological disorders if left untreated.