Anti-Glomerular Basement Membrane (GBM) Antibody
Antibodies against a protein in the filters of your kidneys. A positive result is linked to anti-GBM disease, a rare condition that clinicians usually follow up quickly.
AI-verified against cited sources. Awaiting expert reviewAlso called anti-GBM, GBM AbLOINC 59394-7
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What it is
The glomeruli are the tiny filters in your kidneys. Their walls contain a protein called type IV collagen. In anti-GBM disease, the immune system makes antibodies against one part of that collagen, which is also found in the lungs. This test measures those antibodies in your blood. Labs use different methods, and each reports in its own units.
Why it matters
Anti-GBM disease is rare, but it can damage the kidneys quickly and sometimes the lungs as well. These antibodies are the main blood finding in the condition, so a positive result usually leads to fast follow-up, often including a kidney biopsy. Treatment aims to remove the antibodies and calm the immune system, and starting early is linked to better kidney outcomes. A negative result does not completely rule the condition out, because some people have antibodies that certain tests miss.
If it’s high
A result above your lab's cutoff means antibodies against the glomerular basement membrane were found. This is the main blood finding in anti-GBM disease, which is also called Goodpasture disease when the lungs are involved. A positive result is usually checked with a second test or a kidney biopsy, because some assays can give false positives.
Common causes
- A false-positive result, which can happen because some assays also react with other parts of type IV collagen
- Anti-GBM disease affecting the kidneys, or the kidneys and lungs
- Anti-GBM antibodies together with another kidney condition, such as ANCA-related vasculitis or membranous nephropathy, which happens more often than chance would predict
What can help
- Ask how quickly the result can be confirmed, for example with a repeat test or a kidney biopsy
- Ask which other tests are needed now, such as kidney function, urine tests and ANCA antibodies
- Tell your clinician right away about blood in the urine, passing less urine, new swelling, coughing up blood or shortness of breath
Usual ranges
What labs print as the reference range, by who was tested. Ranges differ a little between labs, so the range on your own report is the one your result is judged against.
For adults: 0–19 AU/mL. Source: ARUP Laboratories, UI Health Care (University of Iowa Hospitals & Clinics) Laboratory Services Handbook.
- Adults (this one applies)0–19 AU/mL
Sources: ARUP Laboratories, UI Health Care (University of Iowa Hospitals & Clinics) Laboratory Services Handbook
What can affect your result
- Test method: ELISA, chemiluminescence, multiplex bead and immunofluorescence assays differ in sensitivity and in how often they give false positives
- Some people with anti-GBM disease have antibodies that standard ELISAs do not detect but immunofluorescence can
- Treatment lowers antibody levels, so the timing of the test matters
- Units and cutoffs: each lab and kit uses its own, so compare only with the range on your own report
- Methods differ: ELISA, chemiluminescence, multiplex bead and immunofluorescence assays vary in sensitivity, and some assays give false positives.
- ARUP notes that its bead assay can react with other chains of type IV collagen, which can give a false-positive result.
- Some people with anti-GBM disease have antibodies that standard ELISAs miss but immunofluorescence can detect.
- Treatment that lowers antibody levels can lower the result.
When to talk to a clinician
Early treatment is linked to better kidney outcomes, so a positive result is usually followed up quickly. If your lab or clinician has not already contacted you, call the clinician who ordered the test soon. Call 911 or your local emergency number if you cough up blood, have trouble breathing, or pass very little or no urine.
Questions you could ask
- Which method does my lab use, and could a second method add information?
- How soon can we confirm this result, and with which test?
- Which kidney and lung tests do I need now?
- Should my urine and kidney function be checked more often?
Questions people ask
Does a positive result mean I have Goodpasture syndrome?
Not by itself. A positive result is a strong clue, but clinicians usually confirm it with another test or a kidney biopsy, because some assays can give false positives. The condition is also called anti-GBM disease.
Can the test be negative if I have anti-GBM disease?
It can, though this is uncommon. Some people have antibodies that standard ELISA tests miss, and using two methods finds more cases. If suspicion stays high, your clinician may use a different method or a kidney biopsy.
Why are the units different between labs?
Each test kit has its own scale, shown as U/mL, AU/mL or an index. The numbers are not interchangeable, so compare your result only with the cutoff printed on your own report.
Show the science and sources
For clinicians and researchers
Anti-GBM antibodies are IgG autoantibodies against the noncollagenous (NC1) domain of the alpha-3 chain of type IV collagen, alpha3(IV)NC1, the target antigen of anti-GBM disease. The disease is a rare small-vessel vasculitis of kidney and lung capillary beds. Most patients present with rapidly progressive glomerulonephritis with widespread crescents, and 40% to 60% have alveolar hemorrhage at the same time (McAdoo and Pusey, CJASN 2017). Treatment aims to remove the antibody quickly, typically with plasma exchange plus immunosuppression, and early treatment is associated with good kidney outcomes in retrospective cohorts. Antibodies are detected by solid-phase immunoassays (ELISA, chemiluminescence, multiplex bead) or by indirect immunofluorescence on kidney tissue. Performance varies by kit. In a comparison of four enzyme immunoassays against immunofluorescence, sensitivity ranged from 94% to 100% and specificity from 68% to 96%, and two kits produced many false positives (J Clin Lab Anal 2002). A chemiluminescence assay and an ELISA agreed on 70% of positives and 98.6% of negatives, and in the 31 patients with biopsy-proven disease the chemiluminescence assay, the commercial ELISA and the authors' own ELISA agreed 100% (Ren Fail 2020). Some patients have conformation-dependent antibodies that commercial ELISAs do not detect but immunofluorescence does (Nephrology 2012). ARUP reports its multiplex bead assay in AU/mL (19 or less negative, 20 to 25 equivocal, 26 or more positive), warns of false positives from reactivity with other type IV collagen chains, and advises that results from the bead assay and immunofluorescence together improve sensitivity and that a positive result be confirmed by renal biopsy. Units (U, AU/mL, antibody index) and cutoffs are kit-specific and not interchangeable.
LOINC 59394-7 (primary), 30343-8, 31406-2, 44446-3. Specimen: serum.
Sources
- Glomerular Basement Membrane Antibody, IgG by Multiplex Bead Assay (test 0051000), ARUP Laboratories
- Glomerular Basement Membrane Antibody, IgG by Multiplex Bead Assay and IFA (test 2008403), ARUP Laboratories
- Anti-Glomerular Basement Membrane Disease, Clinical Journal of the American Society of Nephrology (2017)
- Comparison of four enzyme immunoassays for the detection of immunoglobulin G antibody against glomerular basement membrane, Journal of Clinical Laboratory Analysis (2002)
- Comparison of the performance of a chemiluminescence assay and an ELISA for detection of anti-GBM antibodies, Renal Failure (2020)
- Circulating anti-glomerular basement membrane autoantibodies against alpha3(IV)NC1 undetectable by commercially available enzyme-linked immunosorbent assays, Nephrology (Carlton) (2012)
- Glomerular Basement Membrane Antibodies, IgG, UI Health Care (University of Iowa Hospitals & Clinics) Laboratory Services Handbook
AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.