What does a folate test show?
Folate is vitamin B9. The blood test measures how much of it you have, and it’s usually ordered for one reason: your doctor is working out the cause of an anemia or a set of symptoms that could come from a deficiency.
The short version
- What folate does: in the words of the National Library of Medicine, vitamin B9 “helps your body make healthy new cells.” It’s needed to form red blood cells and to produce DNA.
- Why it’s ordered: most often for symptoms of certain types of anemia, and usually together with a B12 test.
- Low folate has well-documented causes — diet, absorption problems, alcohol, certain medicines, and dialysis among them.
- High folate generally reflects intake: folic acid supplements, or fortified foods. MedlinePlus’s folic acid test entry doesn’t list conditions that cause a high result.
- Medicare: covered when a deficiency is genuinely suspected, not when it rides along in a vitamin panel. Medicare pays the lab $14.70 when covered.
What causes low folate
The National Library of Medicine defines folate deficiency as “a lower-than-normal amount of folic acid, a type of vitamin B, in your blood,” and lists these causes:
- Absorption problems — diseases that affect how folic acid is absorbed, such as celiac disease and Crohn’s disease
- Excessive alcohol consumption
- Diet — not enough fruits and vegetables. Overcooking them also matters, because heat destroys folic acid
- Increased demand — hemolytic anemia, where the body needs more folic acid to keep making red blood cells
- Certain medications — phenytoin, sulfasalazine, and trimethoprim-sulfamethoxazole are the ones named
- Kidney dialysis
The symptoms listed are fatigue, irritability or diarrhea, poor growth, and a smooth, tender tongue. Left unaddressed, folate deficiency can lead to anemia with abnormally large red blood cells — the same signature that low B12 produces, which is why the two tests so often travel together. More on the B12 half of that pair →
What this test is not for
It’s worth being direct about this, because it’s a common search and a reasonable worry. A folate test is not a cancer test. It isn’t used to screen for cancer, and it isn’t used to diagnose one. What it’s used for is the deficiency picture above: anemia, absorption problems, and monitoring a deficiency already found.
There is a real body of research on folate and cancer risk, but it’s about folate intake across years, the findings differ by cancer type, and researchers are still working out the picture. None of that is something a single folate number on your report can answer, in either direction. If you’ve read something that worried you, bring the actual article to your doctor — that’s a better use of the question than a number.
We don’t print a normal range here. MedlinePlus says it plainly for this test: “Normal value ranges may vary slightly among different labs. Talk to your provider about the meaning of your test results.” Compare your number to the range on your own report. Why that range is not the whole story →
Before the test
You may be asked to fast. MedlinePlus notes that before a vitamin B blood test “you may need to fast (not eat or drink) for several hours.” Whether you do depends on what else is being drawn, so ask when the test is ordered. More on fasting before blood work →
What Medicare pays
Folate lives under the same regional vitamin policies as B12, and carries the same trap. A targeted test backed by findings is covered. A vitamin panel, or a “check my levels” order, is treated as screening and denied.
There’s a wrinkle specific to folate. Because it’s so often ordered alongside B12, a folate line without its own justification can be the one uncovered item on an otherwise covered blood draw — which is how a signature form ends up in front of you for a routine-looking test.
| Test | Code | Medicare pays the lab | You pay if covered |
|---|---|---|---|
| Folate | 82746 | $14.70 | $0 |
| Vitamin B12 | 82607 | $15.08 | $0 |
If you’re asked to sign something before this draw, it’s worth knowing what that form is first. What to do before you go →
The folate test page has the full coverage rules and what it costs to buy directly. Folate cost and Medicare coverage →
Sources
- MedlinePlus (National Library of Medicine): Folate deficiency
- MedlinePlus (National Library of Medicine): Folic acid - test
- MedlinePlus (National Library of Medicine): Vitamin B Test
- Medicare coverage detail: regional policy LCD L34914
- Medicare payment amounts: CMS Clinical Laboratory Fee Schedule, 2026 Q3
Checked September 23, 2026. This page explains what the test measures. It is not medical advice and cannot interpret your result. Your doctor can.
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