RBC Folate Blood Test (Folate, Red Blood Cell)
An RBC folate blood test measures folate held inside red blood cells rather than folate floating in the serum. Because red cells take up folate as they form and carry it for their whole lifespan, the result reflects folate status across a longer stretch of time than a serum measurement does.
About this test
Folate is a B vitamin the body uses for building DNA, dividing cells, and forming red blood cells, and it works closely with vitamin B12 in the process that recycles homocysteine. It appears in leafy greens, legumes, and — because grain products in the United States are fortified with it — in a good deal of ordinary food.
This test looks specifically at the folate carried inside red blood cells. A red cell takes up folate while it is being formed in the bone marrow and holds that supply for the rest of its life in circulation, a span of roughly a few months.
Who might consider this test?
- People who look into an RBC folate test are often interested in nutrition and B-vitamin status
- Sometimes because of symptoms that can be linked to folate
- Sometimes as part of a wider wellness review
Test details
| Quest code | 467 |
|---|---|
| Methodology | Immunoassay |
| Sample type | Whole blood |
| Collection | Quest patient service center |
Reference range
>280 ng/mL RBC
Reference ranges are general guidance. The range printed on your own laboratory report is the one that applies to your result.
Related tests and panels
Quest resources
Additional details
RBC folate compared with serum folate
These are two different tests and the distinction matters when choosing between them. Serum folate measures what is circulating in the blood right now, and it responds quickly — a folate-rich meal or a supplement taken shortly before the draw can lift it, and a period of poor intake can lower it within days. It is a snapshot of the immediate supply.
RBC folate measures what has been stored inside red cells. Because those cells took up their folate when they were formed and carry it for months, the measurement reflects the average supply over roughly the preceding few months rather than the preceding few days. It is far less sensitive to what someone ate recently, which is precisely why some clinicians prefer it when the question is about longer-term status rather than the current moment.
The practical consequence is that the two can disagree, and neither is wrong when they do. Someone who has recently improved their intake may show an unremarkable serum folate while the red-cell measurement still reflects the earlier period. The opposite pattern happens too. A clinician chooses based on the question being asked, and sometimes orders both to see the immediate and the accumulated picture side by side. RBC folate is the more involved measurement of the two, which is part of why serum folate remains the more common first-line choice.
Why folate and vitamin B12 are usually considered together
Folate and vitamin B12 work in the same biochemical pathway, and a shortfall in either can produce a similar pattern in the blood, with red cells forming larger than expected. Because the two look alike from the outside, clinicians very commonly measure them together rather than one alone — establishing which of the two is involved changes what happens next, and that determination belongs to a clinician.
The pairing has a further reason behind it. Folate can influence the blood picture that B12 status would otherwise produce, without affecting the other consequences of low B12. That interaction is well recognized, and it is the reason a clinician generally wants both figures in hand before drawing conclusions about either, and why decisions about folate supplementation are made by a clinician who knows the B12 picture too. Nothing on this page provides supplementation guidance.
What else it may be read alongside
RBC folate is frequently part of a broader nutritional or blood-health review. A complete blood count is a common companion, since it describes the number and size of red cells and shows the pattern that folate and B12 status can influence. Homocysteine is sometimes included as well, because folate and B12 both take part in the pathway that processes it.
A clinician weighs the pattern across these results, along with diet, medications, symptoms, and personal history, before drawing any conclusions. No single marker stands in for the whole story, and the result is a starting point for a conversation rather than an answer by itself.
What ordering this test involves
This is a self-pay test ordered online, with the physician order included, so it does not require an existing relationship with a physician or an insurance authorization before booking. The price appears in the order box on this page rather than in the text; it is a single flat amount covering the order, the draw, and the laboratory analysis, with nothing billed afterward and no separate facility charge.
Because the test is self-pay, the amount is not submitted to insurance and does not apply toward a deductible. One point is worth pausing over before ordering: RBC folate is a more specialized measurement than serum folate and is priced considerably higher. If the question is about the immediate supply rather than the accumulated picture, the serum folate test is both the more suitable choice and the substantially cheaper one, and it is available here as well. Anyone whose plan covers either test may prefer to go through their clinician instead.
Order online and a physician order is included — no doctor's visit and no insurance needed. Your sample is collected at a Quest Diagnostics patient service center.
Laboratory results should always be interpreted by a licensed clinician who knows your health history. This page is information about a test, not medical advice.
Frequently asked questions
What does an RBC folate test measure?
It measures folate stored inside red blood cells. Because red cells take up folate as they form and carry it for their whole lifespan, the result reflects folate status across a longer window than a serum folate measurement.
How is RBC folate different from serum folate?
Serum folate reflects what is circulating right now and can shift with a recent meal or supplement. RBC folate reflects the average supply over roughly the preceding few months. They answer different questions and can disagree without either being wrong.
Which folate test should I consider?
It depends on the question. Serum folate suits questions about the immediate supply and is the more common first-line choice; RBC folate suits questions about longer-term status. A clinician chooses based on what they are exploring, and sometimes orders both.
Is folate the same thing as folic acid?
They are closely related but not identical. Folate is the term for the B vitamin as it occurs in food; folic acid is the synthetic form used in supplements and in fortified grain products, which the body converts into the active forms it uses.
Is folate often checked with vitamin B12?
Yes, very commonly. The two work in the same pathway and a shortfall in either can produce a similar blood picture, so clinicians usually measure them together, often with a complete blood count, to see which is involved.
Do I need to fast before an RBC folate test?
No preparation instructions are listed for this test, though people follow any instructions their ordering clinician provides. People should still follow whatever preparation instructions their ordering clinician provides, since other tests drawn at the same time may differ.
Do I need insurance or a doctor visit to order this test?
No. It is a self-pay test ordered online with the physician order included. The listed price in the order box covers the order, the draw, and the laboratory analysis, and because it is self-pay the amount is not submitted to insurance.
Can I get the Folate, RBC test without a doctor's visit or insurance?
Yes. The $199 cash price includes an independent physician's order, so no referral is needed, and insurance is never involved.