Vitamin B12 - Active

Other names: Active B12

check icon Optimal Result: 37.5 - 165 pmol/L.

What is Active Vitamin B12?

Active Vitamin B12, also known as holo-transcobalamin (holo-TC), represents vitamin B12 that is bound to the transport protein transcobalamin. This complex is the biologically active form of B12 that can be taken up by cells via specific receptors. In contrast, most circulating B12 is bound to haptocorrin and is considered metabolically inactive. By measuring only the active fraction, this test provides a more accurate picture of how much usable B12 your body actually has available.

Why this marker is important

Vitamin B12 is essential for red blood cell formation, normal nerve function, DNA synthesis, and methylation processes. A deficiency can lead to anemia, neuropathy (numbness, tingling, burning sensations), cognitive changes, mood disturbances, and fatigue. Total serum B12 can be misleading because it includes inactive forms and may appear normal in people with functional deficiency, chronic disease, or altered binding proteins. Active B12 is more sensitive for detecting early or borderline deficiency, especially in individuals with gastrointestinal issues, pernicious anemia, long-term use of metformin or acid-suppressing drugs, vegetarian or vegan diets, or older age.

How Active B12 differs from total B12

  • Total B12: measures all circulating B12 (active + inactive).

  • Active B12 (holo-TC): measures only the fraction that can be delivered into cells.

Someone can have a normal or even high total B12 but low active B12, indicating that much of the circulating vitamin is not available for cellular use. For this reason, many clinicians prefer active B12, especially when symptoms suggest deficiency or total B12 is borderline.

Associated symptoms and conditions

Low active B12 is associated with:

  • Fatigue and low energy

  • Pale skin or anemia

  • Numbness, tingling, or burning in hands and feet

  • Balance problems, muscle weakness, or gait changes

  • Memory issues, brain fog, or difficulty concentrating

  • Mood changes, irritability, or depression

  • Glossitis (inflamed, sore tongue)

Conditions commonly linked to low active B12 include pernicious anemia, atrophic gastritis, celiac disease, inflammatory bowel disease, gastric or intestinal surgery, pancreatic insufficiency, chronic use of metformin or proton pump inhibitors, and low intake of animal products.

How this test is used

Active Vitamin B12 is often ordered when:

  • Symptoms suggest B12 deficiency but total B12 is normal or borderline.

  • There is suspected malabsorption or autoimmune B12 deficiency.

  • The patient is older, vegetarian/vegan, or on medications that impair B12 absorption.

For a more complete assessment, active B12 is frequently interpreted alongside total B12, methylmalonic acid (MMA), and homocysteine. Elevated MMA and/or homocysteine with low or borderline active B12 strongly supports functional B12 deficiency at the tissue level.

How to support healthy Active B12 levels

Management depends on the underlying cause and lab values, but may include:

  • Dietary changes: increasing intake of B12-rich foods (meat, fish, eggs, dairy, fortified foods), especially for people with low animal-product intake.

  • Oral supplementation: cyanocobalamin, methylcobalamin, or hydroxocobalamin, depending on clinician preference and patient needs.

  • Sublingual or high-dose oral B12: may help in mild absorption issues.

  • Injections: intramuscular or subcutaneous B12 for more severe deficiencies, pernicious anemia, or significant malabsorption.

  • Addressing root causes: treating gut conditions, reviewing medications that impair B12 absorption, and optimizing stomach acid and intrinsic factor when appropriate.

Always discuss any abnormal result or new supplement plan with a qualified clinician.

What does it mean if your Vitamin B12 - Active result is too high?

A high Active Vitamin B12 level is less common and usually reflects recent supplementation (oral, sublingual, or injections) or high intake from fortified foods. In most cases, elevated active B12 due to supplementation is not harmful and simply indicates good availability of usable B12. Rarely, very high B12 levels without supplementation may be associated with underlying medical conditions and should be discussed with a healthcare provider. Your clinician will interpret this result together with your total B12 level, clinical history, and other lab markers.

All Your Lab Results.
One Simple Dashboard.

What does it mean if your Vitamin B12 - Active result is too low?

A low Active Vitamin B12 level suggests that your cells are not getting enough usable B12, even if your total B12 appears normal. This can contribute to fatigue, anemia, nerve symptoms (like numbness or tingling), and cognitive or mood changes. Low active B12 often points to absorption problems, autoimmune B12 deficiency, low dietary intake, or medication effects. Your provider may confirm deficiency with additional tests (such as methylmalonic acid or homocysteine) and recommend dietary changes, supplements, or B12 injections depending on the cause and severity.

Laboratories

Bring All Your Lab Results Together — In One Place

We accept reports from any lab, so you can easily collect and organize all your health information in one secure spot.

lab corp logo
genova diagnostics logo
quest diagnostics logo
dutch test logo
doctors data logo
vibrant america logo
diagnostic solutions logo
zrt laboratory logo
the great plains laboratory logo
cyrex laboratories logo
spectracell logo

Pricing Table

decoration

Personal plans

$15/ month

Complete Plan

Access your lab reports, explanations, and tracking tools.

  • Import lab results from any provider
  • Track all results with visual tools
  • Customize your reference ranges
  • Export your full lab history anytime
  • Share results securely with anyone
  • Begin with first report entered
  • Cancel or upgrade anytime

$250/ once

Unlimited Account

Pay once, access everything—no monthly fees, no limits.

  • Import lab results from any provider
  • Track all results with visual tools
  • Customize your reference ranges
  • Export your full lab history anytime
  • Share results securely with anyone
  • Receive 10 reports entered for you
  • Skip the $15/month subscription — no recurring payments ever

$45/ month

Pro Monthly

Designed for professionals managing their clients' lab reports

  • Import lab results from any provider
  • Track lab results for multiple clients
  • Customize reference ranges per client
  • Export lab histories and reports
  • Begin with first report entered by us
  • Cancel or upgrade anytime

About membership

What's included in a Healthmatters membership

microscope icon Import Lab Results from Any Source

person icon See Your Health Timeline

book icon Understand What Your Results Mean

textbook icon

textbook icon Visualize Your Results

folder icon

folder icon

card icon Securely Share With Anyone You Trust

Let Your Lab Results Tell the Full Story

What Healthmatters Members Are Saying

5 stars rating

I have been using Healthmatters.io since 2021. I travel all over the world and use different doctors and health facilities. This site has allowed me to consolidate all my various test results over 14 years in one place. And every doctor that I show this to has been impressed. Because with  any health professional I talk to, I can pull up historical results in seconds. It is invaluable. Even going back to the same doctor, they usually do not have the historical results from their facility in a graph format. That has been very helpful.

Anthony

Unlimited Plan Member since 2021

5 stars rating

What fantastic service and great, easy-to-follow layouts! I love your website; it makes it so helpful to see patterns in my health data. It's truly a pleasure to use. I only wish the NHS was as organized and quick as Healthmatters.io. You've set a new standard for health tracking!

Karin

Advanced Plan Member since 2020

5 stars rating

As a PRO member and medical practitioner, Healthmatters.io has been an invaluable tool for tracking my clients' data. The layout is intuitive, making it easy to monitor trends and spot patterns over time. The ability to customize reports and charts helps me present information clearly to my clients, improving communication and outcomes. It's streamlined my workflow, saving me time and providing insights at a glance. Highly recommended for any practitioner looking for a comprehensive and user-friendly solution to track patient labs!

Paul

Healthmatters Pro Member since 2024

Use promo code to save 10% off any plan.

Frequently asked questions

Healthmatters is a personal health dashboard that helps you organize and understand your lab results. It collects and displays your medical test data from any lab in one secure, easy-to-use platform.

  • Individuals who want to track and understand their health over time.
  • Health professionals, such as doctors, nutritionists, and wellness coaches, need to manage and interpret lab data for their clients.

With a Healthmatters account, you can:

  • Upload lab reports from any lab
  • View your data in interactive graphs, tables, and timelines
  • Track trends and monitor changes over time
  • Customize your reference ranges
  • Export and share your full lab history
  • Access your results anytime, from any device

Professionals can also analyze client data more efficiently and save time managing lab reports.

Healthmatters.io personal account provides in-depth research on 4000+ biomarkers, including information and suggestions for test panels such as, but not limited to:

  • The GI Effects® Comprehensive Stool Profile,
  • GI-MAP,
  • The NutrEval FMV®,
  • The ION Profile,
  • Amino Acids Profile,
  • Dried Urine Test for Comprehensive Hormones (DUTCH),
  • Organic Acids Test,
  • Organix Comprehensive Profile,
  • Toxic Metals,
  • Complete Blood Count (CBC),
  • Metabolic panel,
  • Thyroid panel,
  • Lipid Panel,
  • Urinalysis,
  • And many, many more.

You can combine all test reports inside your Healthmatters account and keep them in one place. It gives you an excellent overview of all your health data. Once you retest, you can add new results and compare them.

If you are still determining whether Healthmatters support your lab results, the rule is that if you can test it, you can upload it to Healthmatters.

shield icon

We implement proven measures to keep your data safe.

At HealthMatters, we're committed to maintaining the security and confidentiality of your personal information. We've put industry-leading security standards in place to help protect against the loss, misuse, or alteration of the information under our control. We use procedural, physical, and electronic security methods designed to prevent unauthorized people from getting access to this information. Our internal code of conduct adds additional privacy protection. All data is backed up multiple times a day and encrypted using SSL certificates. See our Privacy Policy for more details.

gdpr compliance image hipaa compliance image