COMPLEMENT C3 & C4, SERUM

Complement C3 & C4, Serum

What it is

The Complement C3 & C4, Serum test measures the levels of two important proteins (C3 and C4) in the complement system, a part of the immune system that helps the body fight infections and clear damaged cells. These proteins play a key role in inflammation and defense against bacteria and viruses.

Uses

This test is used to evaluate immune system activity and is commonly ordered in the diagnosis and monitoring of autoimmune disorders such as systemic lupus erythematosus (SLE), rheumatoid arthritis, and certain kidney diseases (like glomerulonephritis). It may also help in assessing recurrent infections or abnormal inflammatory responses.

Symptoms That May Lead to the Test

Doctors may recommend this test if you experience persistent joint pain, swelling, skin rashes (such as butterfly rash in lupus), unexplained fevers, recurrent infections, or kidney-related symptoms such as swelling in the legs, foamy urine, or high blood pressure.

Abnormal Results

Low C3 and/or C4 Levels: May indicate active autoimmune disease (such as lupus), severe infections, certain kidney disorders, or hereditary complement deficiencies.

High C3 and/or C4 Levels: May occur in acute inflammation, infections, or metabolic conditions like obesity and diabetes, reflecting heightened immune activity.

Normal Results: Suggests no current abnormalities in complement activity, though clinical context and other immune tests are often required for interpretation.

Risks

The test requires a simple blood draw, which has minimal risks such as slight bruising, mild pain, or temporary dizziness at the puncture site. These effects are mild and short-lived.