Not just your B12 level — whether your cells can use it
The short answer
Comprehensive B12 Deficiency Panel bundles 3 tests — Vitamin B12, Methylmalonic Acid (MMA) and Homocysteine — for $79.99 plus one $6 lab processing fee (about $26.66 per test). Fast 8–12 hours before the draw; results post in 5–12 business days. Physician-authorized with no doctor's visit or insurance needed; one draw at Quest or Labcorp.
Other Labs
Starting at $193
+ lab fees
TestWell
$79.99
+ $6 lab processing fee
A serum B12 test alone misses early and borderline deficiency — levels can look 'normal' while your cells are already running short. This panel adds the two functional markers clinicians use to settle the question: methylmalonic acid (MMA), which accumulates early and specifically when usable B12 is low, and homocysteine, which rises with both B12 and folate deficiency. Read together, the pattern is diagnostic: elevated MMA with elevated homocysteine points to true B12 deficiency, while elevated homocysteine with normal MMA points to folate instead. It's the right panel when B12 came back borderline, when deficiency symptoms (fatigue, numbness and tingling, brain fog, memory changes) persist despite a normal B12, or when you're verifying that supplementation is actually working. Note: MMA is a specialty assay, so results take longer than routine bloodwork.
Vitamin and nutrient testing identifies deficiencies that can drive fatigue, immune dysfunction, neurological symptoms, and long-term disease risk — and confirms that supplementation is working.
Anyone with restrictive diets (vegan, low-fat, low-carb), malabsorption conditions, fatigue, hair loss, mood changes, or currently supplementing and wanting to verify dosing.
Sample Type
Blood draw
Fasting
Required
Results In
5–12 business days
Biomarkers
3 across 3 tests
3 individual tests · 3 biomarkers measured — each test linked so you can learn more.
Fasting for 8–12 hours recommended (homocysteine reads most accurately fasted). Water is okay. MMA is a specialty send-out assay — allow extra time for results.
What can throw off this result
Physician-reviewed “Before your test” pages — what each factor does, for how long, and what to do about it.
A Comprehensive B12 Deficiency Panel costs $79.99 at TestWell — $85.99 all-in when ordered alone, because the $6 lab processing fee is charged once per order, with no draw fee or physician fee added. With insurance, what you pay depends on your deductible and your plan's negotiated rate; TestWell's price is fixed before the draw and is HSA/FSA-eligible.
| Where you order | Price | One test, all-in | Notes |
|---|---|---|---|
| TestWell (drawn at Quest or Labcorp) | $79.99 | $85.99 | Includes the one $6 lab processing fee, charged once per order |
Competitor prices are read from the linked public pages and re-checked regularly; the labs' sites may add taxes or change prices without notice.
Compare more: Quest Diagnostics price list · Labcorp price list · Quest vs Labcorp · Lab test price checker
The Comprehensive B12 Deficiency Panel includes 3 individual lab tests, bundled at a single panel price below the cost of ordering each test separately. See the full biomarker list and clinical context on the panel page.
Most Comprehensive B12 Deficiency Panel results are available in 5–12 business days after your specimen arrives at the lab. You'll get an email the moment results are ready, with everything viewable in your TestWell portal.
Blood draw. Sample is collected at a Quest, Labcorp, or BioReference patient service center near you, or via at-home phlebotomy where available.
On TestWell, the Comprehensive B12 Deficiency Panel is $79.99. Quest Direct lists comparable bundles at $193. Insurance is not required — pay one all-in price.
Yes — fasting for 8–12 hours recommended (homocysteine reads most accurately fasted). Water is okay. MMA is a specialty send-out assay — allow extra time for results. Following the prep instructions gives you the most accurate result.
Order online at TestWell — we'll generate a digital requisition and route you to the closest in-network lab. 4,000+ Quest, Labcorp, and BioReference patient service centers nationwide.
Common medications can change a Comprehensive B12 Deficiency Panel result without anything being wrong. Common medications can lower Vitamin B12 — check B12 periodically on metformin. Each factor is covered on our physician-reviewed "Before your test" pages; when one applies, the fix is usually to remove it and retest.
Medically reviewed by Youmna DiStefano, MD · Last reviewed September 2026
Related guide
Methylmalonic Acid (MMA) and B12 Deficiency: Why the Test Is Ordered and How to Read It
Starting at $193 at other labs
TestWell Price
$79.99
+ $6 lab processing fee at checkout
No insurance needed · HIPAA compliant
Individual tests that complement this panel
Comprehensive B12 Deficiency Panel
$79.99