Complement Blood Test
The complement blood test measures the level of complement proteins in the blood. Complement proteins are part of the immune system and help fight off infections.
What is the purpose of the test?
The complement blood test is used to:
- Diagnose and monitor autoimmune disorders, such as lupus or rheumatoid arthritis
- Assess the immune system's function in patients with recurrent infections
- Monitor the effectiveness of treatment for certain diseases, such as kidney disease or vasculitis
How is the test performed?
A blood sample is taken from a vein in the arm using a needle and syringe. The sample is then sent to a laboratory for analysis.
What are complement proteins?
Complement proteins are a group of proteins that work together to help fight off infections. There are nine main complement proteins, labeled C1-C9. They play a crucial role in:
- Recognizing and binding to pathogens, such as bacteria and viruses
- Activating the immune system's response to infection
- Helping to remove pathogens from the body
What are the different types of complement tests?
There are several types of complement tests, including:
- CH50 (total hemolytic complement): measures the overall activity of the complement system
- C3 and C4: measure the levels of specific complement proteins
- Alternative pathway test: measures the activity of the alternative complement pathway
What are normal results?
Normal results vary depending on the laboratory and the specific test used. Generally, a normal result is:
- CH50: 30-60 hemolytic units/mL
- C3: 90-180 mg/dL
- C4: 10-40 mg/dL
What do abnormal results mean?
Abnormal results may indicate:
- Autoimmune disorders, such as lupus or rheumatoid arthritis
- Infections, such as sepsis or meningitis
- Kidney disease or vasculitis
- Immunodeficiency disorders, such as complement deficiency
Are there any risks associated with the test?
The risks associated with the complement blood test are minimal and may include:
- Bleeding or bruising at the needle site
- Infection at the needle site
- Dizziness or fainting due to the needle stick
Article last updated on: 15th June 2025.
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