Fibrillarin Antibody (Serum) – Immunoassay
This test measures the presence of antibodies against fibrillarin, a protein found in certain cell nuclei. It may be used to help diagnose autoimmune conditions affecting the kidneys or other organs.
["This test helps assess potential autoimmune kidney disease or related conditions."]
Key facts at a glance
- LOINC
- 49963-2
- Short code
- Fibrillarin Ab Ser Ql
- Synonyms
- Fibrillarin Ab Ser Ql
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- 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
What This Test Measures
Fibrillarin is a nuclear protein involved in RNA processing. When the immune system mistakenly targets this protein, it can indicate an autoimmune response. This test detects antibodies against fibrillarin, which may signal conditions like anti-ribosomal P antibody syndrome or certain forms of lupus or vasculitis.
Why It Might Be Ordered
A healthcare provider may order this test if you have symptoms like kidney problems (e.g., protein in urine, blood in urine), joint pain, rash, or unexplained fatigue. It’s sometimes used alongside other tests to narrow down possible autoimmune diagnoses.
Sample Collection and Preparation
A blood sample is drawn from a vein in your arm. The blood is processed to separate serum (the liquid part after clotting), which is then tested for fibrillarin antibodies using an immunoassay method. This test does not require fasting.
What to Expect Before the Test
No special preparation is needed. You may have a small bruise or slight discomfort at the injection site, but this usually fades quickly. If you’re on blood-thinning medication, let your provider know before the test.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
Fibrillarin Antibody (Serum)
Frequently asked questions
Antibodies against fibrillarin can be associated with autoimmune diseases that affect multiple organs, including the kidneys. While not all positive results indicate a definitive diagnosis, they may prompt further testing (e.g., kidney function tests, biopsies) to explore conditions like anti-ribosomal P syndrome or certain forms of lupus nephritis.
A positive result suggests your immune system may be attacking fibrillarin, which could be linked to autoimmune activity. Your doctor will interpret results in the context of your symptoms, other tests, and medical history to guide next steps.
No, this test alone cannot diagnose autoimmune kidney disease. It may be part of a broader evaluation, including kidney function tests, imaging, and other antibody tests (e.g., anti-dsDNA, anti-Sm).
Sources
- 1
- 2Lab Tests OnlineSource
- 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