What Is the Anti-Glomerular Basement Membrane Test?
The anti-glomerular basement membrane (anti-GBM) test looks for antibodies that attack a part of the kidney known as the glomerular basement membrane (GBM). These are called anti-glomerular basement membrane antibodies. Anti-GBM antibodies can be a sign of kidney damage.
Anti-GBM antibodies attack capillaries in the GBM. These attacks cause problems with kidney function. This can cause blood and blood proteins to leak into your urine.
This test is also known as the GBM antibody test, antibody to human glomerular basement membrane test, or the anti-GBM antibodies test.
Why the Anti-Glomerular Basement Membrane Test Is Performed
The test can help diagnose certain diseases that affect the kidneys. These include anti-glomerular basement membrane disease and Goodpasture syndrome.
When anti-GBM disease only affects the kidneys, it is called anti-GBM glomerulonephritis. When both the kidneys and the lungs are affected, it is called Goodpasture syndrome
The following may be symptoms of both anti-GBM diseases:
- weight loss
- chills and fever
- coughing up blood
- nausea and vomiting
- chest pain
- anemia caused by bleeding
- respiratory failure
- kidney failure
How the Anti-GBM Test Is Performed
The anti-GBM test is performed on a blood sample. No specific preparations are needed before having an anti-GBM test.
To draw blood, a health professional wraps an elastic band around your upper arm. This stops blood flow and make veins in your arm more visible. The needle can then be inserted more easily.
Once a vein is located, the skin around the vein is cleaned with alcohol. The needle is then inserted into your vein. A tube is attached to the end of the needle to collect the blood.
After enough blood is collected, the elastic band is removed from your arm. As the needle is removed, cotton or gauze is placed onto the injection site. Pressure is applied to the cotton or gauze and it is secured with a bandage.
Risks Associated with the Anti-GBM Test
There are few risks involved with having blood drawn. Some bruising may appear at the needle site. Bruising can be minimized by applying pressure to the area for several minutes after the needle is removed.
In very rare cases, having blood drawn has the following risks:
- fainting or lightheadedness
- excessive bleeding
- hematoma (an accumulation of blood beneath the skin)
What to Expect After the Test
Normally, there are no anti-GBM antibodies in the blood.
If anti-GBM antibodies are found in your blood, it means you may have anti-GBM disease or Goodpasture syndrome.
If a diagnosis is made of either anti-GBM disease or Goodpasture syndrome, there are several treatments.
Plasmapheresis takes blood out of the body and removes the portion containing antibodies.
Immunosuppression with methylprednisolone prevents the production of more antibodies.
Some of the side effects of anti-GBM diseases may be preventable. Antibiotics may be used to reduce the risk of lung infections.