Laboratory Blood Test: What You Need to Know About Testing and Your Results

This test analyzes a small sample of your blood to measure important substances, such as cells, chemicals, proteins, or other markers. The results give your healthcare provider valuable information about how your body is working and can help detect or monitor many different health conditions.

This test measures two different types of antibodies in your blood. Neutrophil Cytoplasmic Antibodies (ANCA) are autoantibodies that target neutrophils, a type of white blood cell. These antibodies are primarily associated with vasculitis, a group of disorders causing inflammation of blood vessels. Saccharomyces cerevisiae antibodies (ASCA) target a type of yeast and are commonly found in patients with Crohn's disease, a type of inflammatory bowel disease.

Your provider may order this test as part of a routine checkup, to help diagnose the cause of symptoms you are experiencing, to screen for certain diseases, or to track how well a treatment or medication is working. In some cases, it may also be needed before a surgical procedure.

Your doctor may order this test if you have symptoms suggesting vasculitis (such as fever, fatigue, joint pain, skin rashes, or kidney problems) or inflammatory bowel disease (such as abdominal pain, diarrhea, weight loss, or bloody stools). The test helps distinguish between different types of vasculitis and between Crohn's disease and ulcerative colitis.

The test is performed by drawing a small amount of blood, usually from a vein in your arm. A trained professional will clean the area, place a tight band around your arm, and insert a thin needle to collect the sample. The procedure typically takes only a few minutes and may cause brief, mild discomfort.

A healthcare professional will draw a small blood sample from a vein in your arm. The blood is then sent to a laboratory where it is analyzed for the presence of IgG and IgA antibodies against neutrophils and Saccharomyces cerevisiae. You do not need to fast before this test.

Your results are compared with reference ranges, which show the levels considered typical for healthy people. A result outside the expected range does not always mean you have a serious problem, so it is important to review your results with your healthcare provider, who can explain what they mean for you.

Results are typically reported as positive or negative, often with a titer (concentration) value. A positive ANCA test may indicate conditions like granulomatosis with polyangiitis, microscopic polyangiitis, or other forms of vasculitis. A positive ASCA test, especially when combined with a negative p-ANCA, strongly suggests Crohn's disease. However, results must be interpreted in context with your symptoms and other test findings.