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: Beta-2 Transferrin, Serum, Qualitative

Published: August 9, 2026Updated: August 17, 2026

: Beta-2 transferrin is a protein that is normally found almost exclusively in cerebrospinal fluid (CSF). This test checks whether beta-2 transferrin is present in a serum sample, which can help confirm or rule out a fluid leak such as a CSF leak.

Quick summary

[": Beta-2 transferrin testing looks for a CSF-specific protein to help identify whether cerebrospinal fluid is present where it should not be."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
43867-1
Short code
B2TF
Synonyms
B2 Transferrin Ser Ql
Category
chemistry
Sample
serum
Container
Red-top serum tube (no anticoagulant) or serum separator tube (SST)
Units
N/A
Ref low
200
Ref high
350
Fasting
false
Population
adult
Sex
all
Age range
0–999 years
Method
Immunofixation Electrophoresis / Western Blot
CPT
84165
SNOMED
104686007
Specimen volume
1 mL serum (minimum 0.5 mL)
Stability
Stable for 7 days at 2-8°C; for longer storage, freeze at -20°C or below. Avoid repeated freeze-thaw cycles.
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
24–72 hours
Order
routine

: What Beta-2 Transferrin Is

: Beta-2 transferrin is a form of the protein transferrin that has had specific sugar groups removed. It is produced almost entirely within the central nervous system and is therefore a well-known marker for cerebrospinal fluid. Its presence outside the CSF space, such as in nasal or ear drainage, can suggest that CSF is leaking.

: Why the Test Is Ordered

: A healthcare provider may order beta-2 transferrin testing when someone has clear drainage from the nose or ear, or after head trauma or surgery, to see whether the fluid is CSF. Testing a serum sample can serve as a comparison or reference in selected situations, though the test is most commonly performed on the drainage fluid itself.

: How the Test Is Performed

: The test uses a laboratory method that separates proteins and identifies the specific beta-2 transferrin band, commonly an electrophoresis-based technique. A blood sample is collected from a vein in the arm, and the serum is separated and analyzed. Your provider will explain any preparation needed.

: What Results Mean

: A negative result generally means that beta-2 transferrin was not detected in the sample. A positive or detected result may indicate the presence of CSF and warrants prompt medical follow-up. Your provider will interpret results together with your symptoms, imaging, and other tests; reference details vary by laboratory.

Reference range

NCBI: Transferrin 200-350 mg/dLN/A

Specimen: serum

No special preparation required. Fasting is not necessary. Patient should be informed about the specimen collection procedure.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

: Beta-2 transferrin is a highly specific marker for cerebrospinal fluid and is valuable in evaluating suspected CSF leaks. Because a confirmed CSF leak can carry risks such as infection and low-pressure headaches, results should be reviewed promptly by the ordering clinician in the full clinical context.

Short name

: Beta-2 Transferrin (Serum)

Frequently asked questions

: Does this test diagnose a CSF leak on its own?
: No. Beta-2 transferrin testing is one piece of information. Diagnosis usually combines symptoms, physical examination, imaging, and sometimes testing of the drainage fluid itself.
: Is a blood draw needed for this test?
: This particular test is performed on a serum sample, which requires a routine blood draw from a vein. Your healthcare team will tell you whether additional fluid samples are being collected.
: Do I need to fast before this test?
: Fasting requirements depend on the laboratory and your provider's instructions. Ask your provider or the testing laboratory whether any preparation is needed before your sample is collected.
  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 17, 2026. · Read our editorial policy