5metetrahydrofolatecsfql
This test checks for the presence of 5-Methyltetrahydrofolate, the active form of folate, in the cerebrospinal fluid surrounding the brain and spinal cord.
{"Measures active folate levels in the fluid around the brain and spinal cord","Helps diagnose folate-related neurological conditions","Requires a lumbar puncture (spinal tap) to collect the sample","Low levels may indicate cerebral folate deficiency","Important for evaluating certain brain development and neurological disorders"}
Key facts at a glance
- LOINC
- 33274-2
- Short code
- 5MTHF CSF
- Synonyms
- 5Me-tetrahydrofolate CSF Ql
- Category
- chemistry
- Sample
- csf
- Container
- Sterile polypropylene cryovial or sterile CSF collection tube (no preservatives)
- Units
- N/A
- Ref low
- 2.7
- Ref high
- 17
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–120 years
- Method
- Liquid chromatography-tandem mass spectrometry (LC-MS/MS) or High-performance liquid chromatography (HPLC) with electrochemical detection
- CPT
- 83789
- SNOMED
- 104171000
- Specimen volume
- 1-2 mL of CSF
- Stability
- Store at -70°C or below. Stable for up to 30 days at -70°C. Avoid repeated freeze-thaw cycles. Transport on dry ice.
- Hemolysis max
- 200
- TAT
- 72–168 hours
- Order
- routine
What is this test?
The 5-Methyltetrahydrofolate (5-MTHF) test measures the amount of this active form of folate in your cerebrospinal fluid (CSF). CSF is the clear, protective fluid that surrounds your brain and spinal cord. Folate (vitamin B9) is essential for many bodily functions, and 5-MTHF is the form of folate that can cross the blood-brain barrier to support brain function.
How is the sample collected?
The sample is collected through a procedure called a lumbar puncture, also known as a spinal tap. A healthcare provider inserts a thin needle between the bones in your lower spine to withdraw a small amount of cerebrospinal fluid. The procedure is generally safe and takes only a few minutes.
Why is this test performed?
This test is typically ordered to evaluate neurological symptoms that may be related to folate deficiency in the brain, such as developmental delays, cognitive issues, movement disorders, or seizures. It helps doctors determine if there is a cerebral folate deficiency, which may not be detected by standard blood folate tests.
Reference range
NCBI: Folate 2.7-17.0 ng/mLN/A
No specific patient preparation required. Inform patient about the lumbar puncture procedure and obtain informed consent. Assist patient into lateral decubitus position with knees drawn to chest.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Frequently asked questions
Do I need to fast before this test?
Is the lumbar puncture painful?
How long does it take to get results?
What do low levels mean?
Sources
- 1
- 2
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.
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 17, 2026. · Read our editorial policy