Complement C4 Blood Test

What is the purpose of this test?

Order this Complement C4 Blood Test, which monitors and diagnoses autoimmune disorders by measuring complement C4 levels in the blood. Complement component 4, also known as C4, is a vital blood test that measures the activity of a specific protein in the blood. This protein is an essential component of the complement system, which consists of nearly 60 different proteins that work alongside the immune system to protect the body from infections and foreign material. The complement system also assists in removing dead cells and waste from the body. 

However, some individuals may inherit a deficiency in specific complement proteins, making them more susceptible to infections or autoimmune disorders. The complement system has nine major proteins labeled C1 through C9. This test specifically measures the activity of C4, providing valuable insights into the functioning of the immune system and the body's ability to fight off infections.

What conditions are associated with abnormal complement C4 levels?

Decreased complement C4 levels may be seen with:

• Recurrent microbial infections
• Autoimmune diseases (lupus and rheumatoid arthritis)
• Hereditary angioedema
• Acquired angioedema
• Various types of kidney diseases
• Cirrhosis
• Hepatitis
• Malnutrition
• Septicemia
• Immune complex disease

Increased complement C4 levels may also be seen with:

• Cancer
• Ulcerative colitis
• Thyroiditis
• Acute myocardial infarction
• Sarcoidosis
• Juvenile rheumatoid arthritis

When should I order a Complement C4 Blood Test?

Individuals may order this test if they are experiencing unexplained inflammation or edema, or if they have symptoms associated with autoimmune disorders such as lupus, they may consider ordering this test. Additionally, healthcare practitioners may order this test if they suspect that someone has an immune complex-related condition and want to check the status of their complement system.