Active Vitamin B12
Active Vitamin B12 (holotranscobalamin) measures the biologically available form of vitamin B12 that can be taken up by cells. It is considered a more accurate early marker of B12 deficiency than tot…
Category: Vitamins & Minerals
Also known as: active vitamin b12, active b12, holotranscobalamin, holotc, aktivni vitamin b12, holo-tc
Reference range: 25.1–165 pmol/L (Source: ABIM)
Standard unit: pmol/L
High values may indicate
High active B12 levels are generally not clinically significant and may reflect adequate or excessive B12 intake or supplementation.
Low values may indicate
Low active B12 levels indicate early vitamin B12 deficiency, even before total B12 levels drop, and may lead to megaloblastic anemia or neurological damage if untreated.
Frequently asked questions
- What is a normal Active Vitamin B12 level?
- A typical reference range for Active Vitamin B12 is 25.1–165 pmol/L (source: ABIM). Reference ranges vary by laboratory, age, and sex, so always compare against the range on your own lab report.
- What units is Active Vitamin B12 measured in?
- Active Vitamin B12 is most commonly reported in pmol/L. Labs in different countries may use other units — you can convert between them with BloodId's blood test unit converter.
- Where do Active Vitamin B12 reference ranges come from?
- BloodId uses ABIM standard reference ranges and educational information from MedlinePlus (see our methodology). Reference ranges still vary by lab, age, and sex, so always compare against your own report.
- Can I track Active Vitamin B12 over time?
- Yes. Upload results from any lab and BloodId charts your Active Vitamin B12 over time against its reference range, so you can see whether the trend is rising, falling, or stable.
Related biomarkers
Source: MedlinePlus, U.S. National Library of Medicine
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