What is complement C3 Test?

During this test, a healthcare professional draws blood from the vein in the arm. After applying an antiseptic, an elastic is wrapped on the upper arm resulting in better blood flow. After they draw blood, the punctured area is covered with a bandage. Blood is collected in a tube and sent for evaluation to a laboratory.

Worldwide, 88 to 201 milligrams per deciliter (mg/dL) or 0.88 to 2.01 grams per litre is the normal range for the test results. Although this range may slightly differ from laboratory to laboratory, it is best advised to consult with a doctor to understand the specific meaning of the test results.

Higher-than-normal or elevated C3 levels indicate that the immune system is active right after an infection or injury. Higher levels could also indicate complex conditions such as diabetes, heart attack, cancer, leukaemia, or ulcerative colitis. If a patient is already under treatment for lupus, higher C3 protein levels usually indicate that the treatment is working.

Lower-than-normal C3 levels indicate a range of conditions in a patient. It could be a sign of autoimmune conditions such as lupus or Crohn’s disease, cirrhosis, bacterial infection, malnutrition, hepatitis, hereditary angioedema, chronic kidney or liver conditions, rare inherited complement deficiencies, or even organ rejection. It is advisable to seek a doctor’s professional opinion.

The complement component 3 test helps a doctor better understand how a patient’s immune system is working at the moment. By understanding the amount of C3 proteins in the body as compared to other components in the complement system, a doctor can diagnose, monitor, and track certain infections, immune deficiencies, or autoimmune disorders in the patient’s body.

There are no preparations needed for this test. It is a simple procedure of a healthcare professional drawing blood from the vein at the back of the hand. During needle insertion, some people feel a sting or prick. While there are no side effects of having blood drawn, minor risks include excessive bleeding or lightheadedness.

When a patient is diagnosed with lupus (an autoimmune condition), his/her body suffers from an impaired immune system response. The clear indicator of this is lower C3 and C4 levels in the body. In fact, with lupus, the total complement level in the body is lower-than-normal. The complement C3 test is one of the many tests used to diagnose this condition.

Complement component 3 (C3) deficiency is a condition that affects C3, the most important and abundant protein in the complement system. This condition is characterised by lower C3 levels that can be either inherited or acquired. Individuals with C3 deficiency are more prone to severe, recurrent infections caused by gram-negative and gram-positive bacteria.