The Complement C4 test measures the level of C4 protein, an essential component of the immune system, in the blood. This test is particularly useful for diagnosing and monitoring autoimmune disorders, including lupus and rheumatoid arthritis. A 1 ml serum specimen, free from hemolysis, is required for this test, which provides results in 2 days. Priced at 850 THB, it aids in understanding the activity of the complement system in the body, helping in the diagnosis and treatment of autoimmune conditions.