Understanding Your Laboratory Test: What It Is, Why It Matters, and What to Expect
This test measures the level of 5-methyltetrahydrofolate, the active form of folate, in your cerebrospinal fluid to help evaluate folate metabolism and neurological health.
{"5-MTHF is the active form of folate essential for brain function and nerve cell maintenance","CSF testing helps assess folate levels in the central nervous system","Abnormal results may indicate folate deficiency, cognitive disorders, or certain neurological conditions","The test requires a lumbar puncture (spinal tap) to collect cerebrospinal fluid","Results help doctors diagnose and monitor conditions affecting folate metabolism in the brain"}
Key facts at a glance
- LOINC
- 34637-9
- Short code
- 5-MTHF CSF
- Synonyms
- 5Me-tetrahydrofolate CSF-mCnc
- Category
- chemistry
- Sample
- csf
- Container
- Sterile polypropylene CSF collection tube (typically 12 x 75 mm or similar). Avoid glass tubes which may affect analyte stability.
- Units
- N/A
- Ref low
- 15
- Ref high
- 40
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 0 years
- Method
- Liquid chromatography-tandem mass spectrometry (LC-MS/MS) or High-performance liquid chromatography (HPLC) with electrochemical detection
- CPT
- 82657 (Folate; 5-methyltetrahydrofolate) - may require modifier for CSF source
- SNOMED
- 313337009
- Specimen volume
- Minimum 0.5 mL; preferred 1-2 mL of CSF for adequate analysis
- Stability
- CSF should be processed within 2-4 hours of collection. If immediate processing not possible, store at 2-8°C for up to 24 hours. For longer storage, freeze at -70°C or below. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 200
- TAT
- 72–168 hours
- Order
- routine
What is this test, and what does it measure in my body?
The 5-Methyltetrahydrofolate (5-MTHF) test measures the concentration of 5-methyltetrahydrofolate in your cerebrospinal fluid (CSF). 5-MTHF is the biologically active form of folate (vitamin B9) that can cross the blood-brain barrier and is crucial for proper brain and nervous system function. This test specifically evaluates folate levels within the central nervous system, which cannot be accurately assessed through blood tests alone.
Why is this test important for my overall health and ongoing care?
Folate plays a vital role in producing DNA, RNA, and proteins, as well as in the synthesis of neurotransmitters like serotonin and dopamine. Adequate levels of 5-MTHF in the CSF are essential for maintaining cognitive function, mood regulation, and proper nerve cell communication. When folate metabolism is impaired, it can lead to various neurological and psychiatric disorders.
How is the test performed, and what should I expect during the procedure?
The test requires a procedure called lumbar puncture (also known as a spinal tap). During this procedure, a healthcare provider inserts a thin needle between the bones in your lower spine to collect a small amount of cerebrospinal fluid. The sample is then sent to a laboratory for analysis to measure the 5-MTHF concentration.
Reference range
Reference range for 5-Methyltetrahydrofolate in CSF: 15-40 ng/mL (34-91 nmol/L). Values may vary by laboratory methodology and reference population.N/A
No special preparation required. Inform patient about lumbar puncture procedure. No fasting necessary.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Low levels of 5-MTHF in CSF may indicate folate deficiency, which can contribute to cognitive impairment, depression, memory problems, and certain neurological disorders. Research has shown associations between reduced CSF folate levels and conditions such as Alzheimer's disease, vascular dementia, Parkinson's disease, and major depressive disorder. Additionally, certain genetic mutations affecting folate metabolism (such as MTHFR polymorphisms) may impact 5-MTHF levels. This test helps healthcare providers diagnose folate-related neurological conditions, differentiate between various types of dementia, and guide treatment decisions including folate supplementation therapy.
Frequently asked questions
Do I need to fast before this test?
Is the lumbar puncture procedure painful?
How long does it take to get results?
What do abnormal results mean?
Can I take folate supplements before the test?
Sources
- 1LOINC Code ReferenceSource
- 2
- 3
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 16, 2026. · Read our editorial policy