Skip to content

Fibrinogen and Angiopeptin (FAP) Ratio in Skull Fluid (CSF)

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

This test measures the ratio of fibrinogen and a related protein called angiopeptin in cerebrospinal fluid (CSF), which may help assess blood-brain barrier integrity or certain bleeding disorders.

Quick summary

["This test may be used to evaluate conditions affecting blood flow or vessel walls in the brain."]

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

Key facts at a glance

LOINC
32864-1
Short code
FMA Angle Skull XR
Synonyms
FMA Angle Skull XR
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
xr-measured
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 This Test Might Be Ordered

Your healthcare provider may recommend this test if you have symptoms like headaches, neurological issues, or if they suspect conditions such as traumatic brain injury, bleeding disorders, or vascular abnormalities in the brain. It could also be part of a broader evaluation for conditions affecting protein exchange between blood and brain tissue.

What to Expect Before the Test

You may receive a spinal tap (lumbar puncture) to collect CSF. This involves lying on your side, having an area near your lower back numbed, and a needle inserted to draw fluid. You might feel pressure or a slight ache afterward. Avoid heavy lifting or strenuous activity for a few hours.

What Happens During the Test

The collected CSF is analyzed for fibrinogen and angiopeptin levels. The test measures their ratio, which can be compared to expected values to identify abnormalities.

What the Results Mean

Results may indicate whether the blood-brain barrier is compromised or if there are changes in protein levels that could signal bleeding, inflammation, or other underlying issues. Your doctor will interpret these results in the context of your symptoms and medical history.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

FAP Ratio in CSF

Frequently asked questions

What does a high or low ratio in this test indicate?
A high or low ratio compared to standard values may signal potential issues with blood flow, vessel integrity, or bleeding in the brain. Your results will be reviewed by a healthcare provider to determine if further testing or treatment is needed.
Does this test require fasting?
No fasting is required for this test. The sample is collected from CSF, so dietary restrictions don’t apply.
How long will it take to get results?
Results are typically available within a few days to a week, depending on lab processing times and your healthcare provider’s workflow. Your doctor will discuss the findings with you during your follow-up visit.
  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