Vitamin B12 - Active ( Holotranscobalamin ) - Serum
Also Known As
Test Parameters Included
- Active Vitamin B12 (Holotranscobalamin): Measures the biologically active fraction of vitamin B12 transported by transcobalamin.
- Vitamin B12 in blood is bound to two proteins: Haptocorrin and Transcobalamin.
- The B12 bound to Transcobalamin (HoloTC) is the only form that can be taken up by cells to support vital functions like DNA synthesis and nerve protection.
- This test measures this specific fraction, making it the most accurate reflection of the B12 actually "at work" in your body.
Department
Methodology
Sample Required
Preparation
Schedule Report
24 Hours
Emergency Report
Yes
Frequently Asked Questions
Why should I take the "Active" B12 test instead of the regular one?
The regular test measures "Total" B12, but much of that is "inactive" and cannot be used by your cells. The Active test shows what is actually available for your body to use.
Can I have a normal B12 result but still be deficient?
Yes! This is a common medical gap. Your Total B12 might look normal, but your "Active" B12 could be low, leading to symptoms.
How long does the B12 take to show in the blood after a supplement?
It can show within hours, which is why you should avoid supplements for at least 24 hours before your blood draw.
Is this test better for vegans?
Yes. Since vegans are at the highest risk for B12 deficiency, this sensitive "Active" test catches the depletion much earlier than standard tests.
What does Holotranscobalamin mean?
It is simply the name of the protein (Transcobalamin) when it is carrying Vitamin B12 (Holo-).
Can stress affect B12 levels?
Stress doesn't directly lower B12, but poor diet and digestive issues caused by stress can lead to lower absorption over time.
Do I need to fast?
No, but it is recommended to avoid a heavy, high-fat meal immediately before the test.
Can a cold or fever affect the result?
No, short-term viral illnesses do not typically affect your Vitamin B12 status.
Why is B12 important for my nerves?
B12 helps maintain the "Myelin sheath," which is the protective coating around your nerves. Without it, the nerves can be damaged.
What is the "Window Period" for B12?
Because the liver stores a lot of B12, it can take months or years for a deficiency to show up after you stop eating B12-rich foods.
Does metformin affect this test?
Yes, long-term use of Metformin (for diabetes) can interfere with B12 absorption.
Is this test done on a home-collection basis?
Yes, a simple serum sample can be collected from your home.
Can children take this test?
Yes, it is particularly useful for children on restricted diets or those showing developmental delays.
How accurate is the CMIA method?
CMIA is considered one of the most accurate and standardized methods for hormone and vitamin testing in modern labs.
How soon will I get my report?
At Dr. Patho Labs & Diagnostics, the report for Active B12 is delivered within 24 hours.
Test Description
Test Code
GDF13
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