St. Luke's Hospital
Main Number: 314-434-1500 Emergency Dept: 314-205-6990 Patient Billing: 888-924-9200
Find a Physician Payment Options Locations & Directions
Follow us on: facebook twitter Mobile Email Page Email Page Print Page Print Page Increase Font Size Decrease Font Size Font Size
America's 50 Best Hospitals
Meet the Doctor
Spirit of Women
Community Health Needs Assessment
Home > Health Information

Multimedia Encyclopedia

    Print-Friendly
    Bookmarks

    Complement component 4

    C4

    Complement component 4 is a blood test that measures the activity of a certain protein that is part of the complement system. The complement system is a group of proteins that move freely through your bloodstream. The proteins work with your immune system and play a role in the development of inflammation.

    There are nine major complement proteins. They are labeled C1 through C9. This test measures C4.

    How the Test is Performed

    A blood sample is needed. This is usually taken through a vein. The procedure is called a venipuncture.

    How to Prepare for the Test

    No special preparation is needed.

    How the Test Will Feel

    When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

    If your child is to have this test performed it may be helpful to explain how the test will feel, and even practice or demonstrate on a doll. The more familiar your child is with what will happen to them, and the purpose for the procedure, the less anxiety he or she will feel.

    Why the Test is Performed

    C3 and C4 are the most commonly measured complement components. Complement activity may be measured to determine how severe a disease is or if treatment is working.

    A complement test may be used to monitor patients with an autoimmune disorder. For example, patients with active lupus erythematosus may have lower-than-normal levels of the complement proteins C3 and C4.

    Complement activity varies throughout the body. For example, in patients with rheumatoid arthritis, complement activity may be normal or higher-than-normal in the blood, but much lower-than-normal in the joint fluid.

    Normal Results

    • Males: 12 to 72 mg/dL
    • Females: 13 to 75 mg/dL

    Note: mg/dL = milligrams per deciliter

    Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

    The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.

    What Abnormal Results Mean

    Increased complement activity may be seen in:

    • Cancer
    • Ulcerative colitis

    Decreased complement activity may be seen in:

    • Bacterial infections (especially Neisseria)
    • Cirrhosis
    • Glomerulonephritis
    • Hepatitis
    • Hereditary angioedema
    • Kidney transplant rejection
    • Lupus nephritis
    • Malnutrition
    • Systemic lupus erythematosus

    Risks

    Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

    Other risks associated with having blood drawn are slight but may include:

    • Excessive bleeding
    • Fainting or feeling light-headed
    • Hematoma (blood accumulating under the skin)
    • Infection (a slight risk any time the skin is broken)

    References

    Introduction to the Complement System. In: Adkinson NF Jr, ed. Middleton’s Allergy: Principles and Practice. 7th ed. Philadelphia, Pa: Mosby Elsevier; 2008:chap 6.

    BACK TO TOP

          A Closer Look

            Tests for Complement component 4

            Review Date: 2/11/2013

            Reviewed By: Ariel D. Teitel, MD, MBA, Clinical Associate Professor of Medicine, NYU Langone Medical Center. Review provided by VeriMed Healthcare Network. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, Bethanne Black, Stephanie Slon, and Nissi Wang.

            The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
            adam.com

            A.D.A.M. content is best viewed in IE9 or above, Fire Fox and chrome browser.


            Back  |  Top
            About Us
            Contact Us
            History
            Mission
            Locations & Directions
            Quality Reports
            Annual Reports
            Honors & Awards
            Community Health Needs
            Assessment

            Newsroom
            Services
            Brain & Spine
            Cancer
            Heart
            Maternity
            Orthopedics
            Pulmonary
            Sleep Medicine
            Urgent Care
            Women's Services
            All Services
            Patients & Visitors
            Locations & Directions
            Find a Physician
            Tour St. Luke's
            Patient & Visitor Information
            Contact Us
            Payment Options
            Financial Assistance
            Send a Card
            Mammogram Appointments
            Health Tools
            My Personal Health
            mystlukes
            Spirit of Women
            Health Information & Tools
            Clinical Trials
            Health Risk Assessments
            Employer Programs -
            Passport to Wellness

            Classes & Events
            Classes & Events
            Spirit of Women
            Donate & Volunteer
            Giving Opportunities
            Volunteer
            Physicians & Employees
            For Physicians
            Remote Access
            Medical Residency Information
            Pharmacy Residency Information
            Physician CPOE Training
            Careers
            Careers
            St. Luke's Hospital - 232 South Woods Mill Road - Chesterfield, MO 63017 Main Number: 314-434-1500 Emergency Dept: 314-205-6990 Patient Billing: 888-924-9200
            Copyright © St. Luke's Hospital Website Terms and Conditions  |  Privacy Policy  |  Patient Notice of Privacy Policies PDF Sitemap St. Luke's Mobile