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Folate (Vitamin B9) in Serum or Plasma

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of folate, a vital B vitamin, in your blood. Folate helps your body make healthy red blood cells and DNA.

Quick summary

["Folate levels help assess your risk of deficiencies that could affect your health."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
81309-7
Short code
FLUBV RNA Ct Resp Qn NAA+probe
Synonyms
FLUBV RNA Ct Resp Qn NAA+probe
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
probe-amp-tar
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your healthcare provider may order this test to check for folate deficiency, especially if you have symptoms like fatigue, weakness, or unusual bleeding. It’s also used in pregnancy to prevent neural tube defects in the baby. Sometimes, it’s part of a broader evaluation for anemia or other blood disorders.

What Does a Low or High Level Mean?

Low folate levels may indicate poor diet, malabsorption issues, or certain medical conditions. High levels might be due to supplements or rare genetic factors. Neither extreme is always harmful, but your provider will interpret results in the context of your overall health.

How Is This Test Performed?

A small blood sample is drawn from a vein in your arm. The blood is sent to a lab where it’s analyzed to measure folate concentration using a specialized immunoassay method.

What Should You Know Before Testing?

If you’re taking folate supplements or multivitamins, let your provider know, as they may affect results. Avoid alcohol and certain medications (like some blood thinners) before testing if instructed.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Folate plays a critical role in cell growth and DNA synthesis. Deficiencies can lead to megaloblastic anemia, increased risk of birth defects, or weakened immune function. High levels may mask vitamin B12 deficiency, which can cause serious neurological issues. Your provider will use these results alongside other tests to guide treatment.

Short name

Serum Folate

Frequently asked questions

Why might my folate levels be checked during pregnancy?
During pregnancy, folate is essential for your baby’s brain and spinal cord development. Low levels can increase the risk of neural tube defects, so monitoring is recommended for all pregnant women.
Can folate supplements affect my test results?
Yes, high doses of folate supplements can temporarily raise your folate levels. If you’re taking them, your provider may adjust testing timing or use a different type of test (like red blood cell folate) for more accurate results.
What symptoms might indicate a folate deficiency?
Common symptoms include fatigue, weakness, pale or swollen skin, shortness of breath, or unusual bleeding. If you experience these, talk to your provider about testing.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy