Order B12 Deficiency Blood Test Panel (Vitamin B12, Methylmalonic Acid, Homocysteine, Folate & CBC) from JustLabs for $75. ($93 all-in for a single-panel order: $75 + one $18 lab & physician order fee per order). Includes 5 tests. Price includes lab processing at Quest Diagnostics. No insurance required.
B12 Deficiency Blood Test Panel (Vitamin B12, Methylmalonic Acid, Homocysteine, Folate & CBC)
A B12 blood test on its own can read normal or borderline in someone who is genuinely deficient. This panel adds the methylmalonic acid test and homocysteine, the markers clinicians use to confirm a deficiency at the tissue level, plus folate and a complete blood count to tell B12 and folate problems apart and check for anemia.
Vitamin B12 is needed to make healthy red blood cells and to keep nerves working. A deficiency can cause fatigue, megaloblastic anemia, a sore tongue, palpitations and numbness or tingling in the hands and feet, and the symptoms can take years to appear. Long-term deficiency can damage nerves permanently, so a clear answer matters.
The problem is that serum B12, the usual test, measures how much B12 is in the blood, not whether your cells have enough. Results in the low-normal or borderline range are common and hard to interpret. That is why this panel measures what B12 does, not only how much is there.
Methylmalonic acid (MMA) builds up when cells lack B12, because an enzyme that clears it depends on B12. The NIH Office of Dietary Supplements calls MMA the most sensitive marker of B12 status, and it is used to confirm deficiency when serum B12 sits in the gray zone.
Homocysteine also rises when B12 runs short, but it rises with low folate too, and with reduced kidney function. Read together, the two markers help tell the cause apart: high MMA and high homocysteine point to B12, while high homocysteine with a normal MMA points away from it.
Folate and the blood count complete the picture. A shortage of either vitamin can cause large, immature red cells, so folate is measured directly, and the CBC shows whether anemia is already present.
If B12 deficiency is confirmed, the next question is why. Pernicious anemia, an autoimmune condition that blocks B12 absorption, is a common cause; our Autoimmune Gastritis Panel tests for the antibodies behind it. If iron is also a concern, see our Iron & Anemia Panel.
Panel Price
$75
All-in
$93
incl. $18 lab & physician fee
You Save
$9
Biomarkers
18
5 tests
Included Tests
Vitamin B12
Measures B12 levels essential for nerve function, DNA synthesis, and red blood cell formation.
Methylmalonic Acid (MMA)
Sensitive marker for B12 deficiency at the cellular level. Elevated when B12 is functionally low.
Homocysteine
Amino acid linked to cardiovascular risk when elevated. Also indicates B vitamin status.
Fasting
Folate, Serum
Measures folic acid levels important for cell division, DNA synthesis, and preventing birth defects.
Complete Blood Count with Differential
Comprehensive blood cell analysis including red cells, white cells, platelets, and white cell differential.
Fasting Required
One or more tests in this panel require fasting for accurate results:
- Do not eat or drink anything except water for 8-12 hours before your blood draw.
- Water is allowed and encouraged - stay hydrated!
- Schedule your lab visit in the morning for convenience.
What This Panel Measures
Serum vitamin B12 (the amount of B12 in your blood); methylmalonic acid (a functional marker that rises when cells lack B12); homocysteine (a functional marker that rises with low B12, low folate or reduced kidney function); serum folate; and a complete blood count with differential, including hemoglobin, hematocrit and MCV, the average size of your red cells.
Who Should Get This Panel
People with a low or borderline B12 result who want a clearer answer; people with fatigue, numbness or tingling, balance problems, memory changes or a sore, smooth tongue; older adults; people who follow a vegan or vegetarian diet; people who take metformin or acid-reducing medicines (proton-pump inhibitors or H2 blockers) long term; people with celiac disease, Crohn's disease or past stomach or bariatric surgery; and people with Hashimoto's, type 1 diabetes or a family history of pernicious anemia.
Further reading: Methylmalonic Acid and B12 Deficiency Testing Guide; Metformin B12 Deficiency Test: What You Need to Know; Serum Folate vs RBC Folate: Which Test Do You Need?.
Health Insights
Conditions Screened
Related Symptoms
When to Get Tested
When symptoms suggest B12 deficiency, when a previous B12 result came back low or borderline, or periodically if you are in a higher-risk group such as long-term metformin use or a vegan diet. If you are deciding whether you were deficient before starting supplements, test before you start. Book a morning appointment after an 8-hour fast.
Understanding Your Results
The results are read together. Low B12 with high methylmalonic acid confirms B12 deficiency, often with high homocysteine and, in more advanced cases, large red cells or anemia on the blood count. A borderline B12 with high MMA usually means deficiency too, while a borderline B12 with normal MMA and homocysteine makes it less likely. High homocysteine with normal MMA points away from B12 and toward low folate (check the folate result) or other causes, such as reduced kidney function or an underactive thyroid. A high B12 is uncommon and is usually from supplements or injections. JustLabs results are informational: review them with a clinician. If B12 deficiency is confirmed, the clinician will look for the cause, often with intrinsic factor and parietal cell antibody tests for pernicious anemia, and decide on treatment, which may be injections or high-dose oral B12.
How much does the B12 Deficiency Panel cost?
The B12 Deficiency Panel costs $75 at JustLabs — $93 all-in, since the $18 lab & physician order fee is charged once per order, however many tests you add. The price is fixed before your blood draw; no insurance or doctor visit needed.
| Option | Price | Order all-in | Notes |
|---|---|---|---|
| B12 Deficiency Panel at JustLabsDrawn at Quest Diagnostics | $75 | $93 | Includes the one $18 fee, charged once per order |
| The same 5 tests ordered individually | $84 | $102 | The panel saves $9 |
Paying with an HSA or FSA? See which lab tests qualify
Frequently Asked Questions
Hospital cash price: $250–$600
$75
+ $18 order fee · $93 all-inOne $18 fee per order covers your Quest blood draw and the independent physician order, however many tests you add.
Save $9 vs. ordering these tests separately
- B12
- MMA
- Homocysteine
- Folate
- CBC w/ Diff
No insurance needed · HSA/FSA eligible
- Physician-ordered
- CLIA-certified Quest lab
- Drawn at Quest Diagnostics
Need Individual Tests?
You can also order any of these tests individually if you don't need the full panel.
Browse Individual TestsRelated Panels
Autoimmune Gastritis Panel
Parietal cell antibodies, intrinsic factor blocking antibodies and fasting gastrin together, for people being evaluated for autoimmune gastritis or pernicious anemia.
Includes 3 tests:
$92
$99
Iron & Anemia Panel
Ferritin, iron and TIBC, vitamin B12, folate and a complete blood count in one draw: checks for anemia and the nutrient shortfalls that most often cause it.
Includes 5 tests:
$39
$43
Vitamin & Mineral Panel
Essential nutrient status including Vitamin D, B12, Folate, Iron & TIBC, Ferritin, and Magnesium.
Includes 6 tests:
$64
$69
Energy & Fatigue Panel
Investigate causes of fatigue with thyroid, iron, B12, Vitamin D, and metabolic markers.
Includes 7 tests:
$72
$76.50
$75
+ $18 order fee · $93 all-in