Type the vitamin B12 result from your blood test and pick its unit. You see it against the lines NIH ODS quotes and the range MedlinePlus prints — including the 150–399 pg/mL band where a result many reports call normal is the one experts check further. Your lab’s range, and your doctor, have the last word.
350 pg/mL is
Above the “subnormal” lines, inside the MMA range in the 150–399 pg/mL range, where experts suggest checking MMA
350 pg/mL ≈ 258 pmol/L (by ODS’s 0.738)
| Line | In the source’s words | Your 350 |
|---|
This is not medical advice and it does not diagnose anything. It shows where a number sits against published lines; what your result means for you depends on your other results, your history and your doctor.
NIH’s Office of Dietary Supplements says “most laboratories define subnormal serum or plasma values as those lower than 200 or 250 picograms per milliliter (pg/mL) (148 or 185 picomols per liter [pmol/L])” — and that between 150 and 399 pg/mL experts suggest an MMA test. MedlinePlus prints 299 to 1054 pg/mL as normal.
How to use it
Find “Vitamin B12” (cobalamin) on your blood test, type the number and pick the unit beside it: US labs print pg/mL, UK and European labs pmol/L. If you also had methylmalonic acid (MMA) or homocysteine measured, open the second box and add them. You see every line in its source’s words, in your own unit as the source prints it, and where your result sits against each. It does not tell you what to take: that is the conversation with your doctor.
The lines, and the range a “normal” result can hide
There is no single cut-off. ODS: “The cutoff between normal vitamin B12 levels and deficiency varies by method and laboratory, but most laboratories define subnormal serum or plasma values as those lower than 200 or 250 picograms per milliliter (pg/mL) (148 or 185 picomols per liter [pmol/L])”. A result between those two is where labs differ, and the checker says so.
The part a normal flag can miss is above them. ODS: “Experts suggest that if a patient’s serum vitamin B12 level is between 150 to 399 pg/mL (111 to 294 pmol/L), the patient’s serum MMA levels should be checked to help confirm a diagnosis of vitamin B12 deficiency”. And it describes “low or marginal vitamin B12 status (200–300 pg/mL [148–221 pmol/L]) without these symptoms is much more common, at up to 40% in Western populations”. So a 350 pg/mL that a report prints without a flag still sits in the range where experts look further.
| Line | pg/mL | pmol/L |
|---|---|---|
| ODS: most labs’ “subnormal”, lower line | under 200 | under 148 |
| ODS: most labs’ “subnormal”, higher line | under 250 | under 185 |
| ODS: experts suggest an MMA test | 150–399 | 111–294 |
| ODS: “low or marginal” status | 200–300 | 148–221 |
| MedlinePlus: normal values | 299–1054 | 219–773 |
The two sources convert slightly differently: ODS’s pairs follow 0.738 pmol/L per pg/mL (from B12’s molar mass, 1,355.4 g/mol), while MedlinePlus prints 299 pg/mL as 219 pmol/L. So the checker compares your number with each line as its source prints it in your unit, rather than converting a printed edge.
MMA and homocysteine
ODS calls MMA the most sensitive marker: “Levels of serum methylmalonic acid (MMA), a vitamin B12-associated metabolite, are the most sensitive markers of vitamin B12 status, and an MMA level greater than 0.271 micromol/L suggests vitamin B12 deficiency”. Its caveat: “However, MMA levels also rise with renal insufficiency and tend to be higher in older adults”. For homocysteine, “a serum homocysteine level higher than 15 micromol/L, for example, suggests vitamin B12 deficiency” — “However, this indicator has poor specificity because it is influenced by other factors, such as low folate levels and, especially, by declines in kidney function”. Many labs print MMA in nmol/L: 0.271 µmol/L is 271 nmol/L.
Common results, and where they sit
| Vitamin B12 | Where it sits |
|---|---|
| 140 pg/mL | Under both lines labs use for “subnormal” |
| 190 pg/mL | Under both lines labs use for “subnormal” |
| 220 pg/mL | Labs differ here |
| 280 pg/mL | Above the “subnormal” lines, inside the MMA range |
| 350 pg/mL | Above the “subnormal” lines, inside the MMA range |
| 399 pg/mL | Above the “subnormal” lines, inside the MMA range |
| 400 pg/mL | Above every line NIH ODS quotes |
| 1200 pg/mL | Above the range MedlinePlus prints |
Worked examples
- 350 pg/mL (the page’s example): above both “subnormal” lines and inside MedlinePlus’s normal values — and inside the 150–399 pg/mL range where ODS says experts check MMA. That is the result this checker exists for.
- 220 pg/mL: under a lab’s 250 line, not under another lab’s 200. Labs differ, and the page says so.
- 280 pg/mL with an MMA of 0.35 µmol/L: above the “subnormal” lines, but under MedlinePlus’s 299 — and the MMA is over ODS’s 0.271 line. That pairing is exactly what the MMA test is for, and it is your doctor’s to read.
- 258 pmol/L on a UK report: the same as about 350 pg/mL, inside ODS’s 111–294 pmol/L MMA range.
Common mistakes
- Reading “normal” as “fine”. A result between 150 and 399 pg/mL can carry no flag and still be the range ODS says experts check further.
- Mixing up pg/mL and pmol/L. 350 pg/mL is about 258 pmol/L; typed in the wrong unit, a normal result looks low or a low one looks normal.
- Testing in pregnancy and reading it like any other time. ODS: “During pregnancy, serum vitamin B12 levels tend to drop, sometimes to subnormal levels, but they usually return to normal after delivery”.
- Reading homocysteine as a B12 test. It rises with low folate and with declining kidney function too — ODS calls its specificity poor.
Frequently asked questions
What are normal vitamin B12 levels?
MedlinePlus prints 299 to 1054 pg/mL (219 to 773 pmol/L) as normal values, and says ranges “may vary slightly among different laboratories”. NIH ODS says most labs call a result under 200 or 250 pg/mL subnormal, and that between 150 and 399 pg/mL experts suggest checking MMA.
What does a B12 blood test show?
The vitamin B12 in your serum or plasma — what ODS calls the usual way to assess B12 status. It does not show everything: ODS names MMA as “the most sensitive markers of vitamin B12 status”, and MedlinePlus says deficiency “should be confirmed by checking the level of a substance in the blood called methylmalonic acid”.
What is the B12 range in pmol/L?
MedlinePlus prints 219 to 773 pmol/L as normal. ODS gives the labs’ “subnormal” lines as under 148 or 185 pmol/L, and the MMA range as 111 to 294 pmol/L. To convert, ODS’s pairs follow 1 pg/mL ≈ 0.738 pmol/L.
Are normal B12 levels different by age?
Neither ODS nor MedlinePlus prints a B12 range by age. ODS does say “MMA levels also rise with renal insufficiency and tend to be higher in older adults”, which matters when an MMA result is read, and that in pregnancy B12 levels “tend to drop”.
What is a low B12 level?
Most labs call under 200 or 250 pg/mL “subnormal” (ODS), and MedlinePlus says “Values of less than 299 pg/mL (219 pmol/L) are a possible sign of a vitamin B12 deficiency.” A result under any of these lines is one to take to your doctor.
What does a high B12 level mean?
MedlinePlus: “An increased vitamin B12 level is uncommon. Usually, excess vitamin B12 is removed in the urine.” It lists liver disease and some blood disorders among the conditions that can raise it — a result over a lab’s range is a question for your doctor.
Read next
- Vitamin B12 as a nootropic
- Is Mind Lab Pro vegan? — where B12 matters most.
- Mind Lab Pro after 50: the age it actually suits
- Feel good, look good: 8 vitamin-packed solutions for low self-esteem
- The Vitamin & Mineral Dose Lookup — B12’s RDA for your age, and the Hemoglobin Level Checker for the blood count it is read with.
This is not medical advice, and nothing here diagnoses or treats anything. It shows where a number sits against published lines; what it means for you is a conversation with your doctor, who knows your other results and your history. Some links on this site are affiliate links: I buy what I review at full price, and a commission never changes a verdict.