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What is anti-GBM antibodies test?
An anti-GBM antibodies test is conducted to check the presence of antibodies against the glomerular basement membrane in your body.
Antibodies are special proteins produced by our immune cells to protect against foreign substances such as bacteria, viruses or any toxin. However, sometimes our body mistakenly produces antibodies against its own tissues and healthy organs, which causes an autoimmune disease.
GBM is a layer in the wall of the blood vessels in the glomeruli - the filters in the kidney, which remove waste products from the blood and retain larger substances like blood cells and proteins.
Anti-GBM antibodies damage the glomeruli and allow proteins and blood cells to pass into the urine. The damage caused by these antibodies can lead to a severe loss of kidney function.
Sometimes, anti-GBM antibodies also attack the blood vessels in the thin walls of the air sacs in the lungs, affecting the exchange of oxygen and carbon dioxide. Injury to these blood vessels causes bleeding into the air sacs and makes it difficult to breathe. When these antibodies affect only the kidneys, it is called anti-GBM glomerulonephritis and when they affect both the kidneys and lungs, it is called Goodpasture syndrome. These diseases are very rare and occur in less than one in a million people. It commonly affects young men aged 15-35 years and older women > 50 years of age.
Normally, the cells lining the inside of the blood vessel protect the basement membrane from these antibodies. However, factors like smoking, infections and exposure to chemicals or metal dust can cause gaps between these cells, allowing antibodies to attack the basement membrane beneath.
