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Complement C1q Blood Test, Quantitative

A Complement C1q Blood Test, Quantitative is particularly useful in evaluating kidney involvement and in monitoring the disease over time.

Sample Report

Test Code: 016824

CPT Code: 86160

Also Known As:

Methodology: Radial immunodiffusion (RID)

Specimen Type: Blood

Preparation: No special preparation required.

Test Results: 10-12 days. May take longer based on weather, holiday or lab delays.


C1q is a subunit of C1, the first component of the complement system, a part of the body’s innate immune system. C1q identifies and binds to immunoglobulin complexed to antigen and activates the complement cascade. C1q levels serve as an indicator of the amount of C1 present. The C1q Blood Test measures levels of C1q to help diagnose an inherited or acquired C1 deficiency.

C1 deficiencies can result in the body’s inability to clear an infection, and are associated with increased occurrences of immune complex diseases such as systemic lupus erythematosus (SLE), polymyositis (chronic inflammation of muscles), glomerulonephritis (inflammation of the kidneys’ filters), and Henoch-Schönlein purpura (inflammation and bleeding of the small blood vessels). Patients with abnormal immunoglobulin levels characterized by conditions such as hypogammaglobulinemia and severe combined immunodeficiency have also been found to have low C1 levels.

Fasting is not required prior to the C1q Blood Test, and results will be available within five to six days. Insurance and a doctor’s order are not required to purchase this test.

For more information about the complement system, see details on the CH50 Blood Test page. Walk-In Lab also offers a C1 Inhibitor Blood Test, C2 Blood Test and C4 Blood Test.

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