BACK TOTOP Browse A-ZSearchBrowse A-ZABCDEFGHIJKLMNOPQRSTUVWXYZ0-9 E-mail FormEmail ResultsName:Email address:Recipients Name:Recipients address:Message: Print-FriendlyBookmarksbookmarks-menuComplement component 3 (C3)C3Complement C3 is a blood test that measures the activity of a certain protein.This protein is part of the complement system. The complement system is a group of nearly 60 proteins that are in blood plasma or on the surface of some cells. The proteins work with your immune system and play a role to protect the body from infections, and to remove dead cells and foreign material. Rarely, people may inherit deficiency of some complement proteins. These people are prone to certain infections or autoimmune disorders.There are nine major complement proteins. They are labeled C1 through C9. This article describes the test that measures C3. How the Test is Performed Blood is drawn from a vein. Most often, a vein from the inside of the elbow or the back of the hand is used.The procedure is as follows:The site is cleaned with an antiseptic. The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood. The provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm. Once the blood has been collected, the needle is removed. The puncture site is covered to stop any bleeding.In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding. How to Prepare for the Test There is no special preparation needed. How the Test will Feel When the needle is inserted to draw blood, some people feel moderate pain. Others may feel only a prick or stinging sensation. Afterward, there may be some throbbing. Why the Test is Performed C3 and C4 are the most commonly measured complement components.A complement test may be used to monitor people with an autoimmune disorder. It is done to see if treatment for their condition is working. When the complement system is turned on during inflammation, levels of complement proteins may go down. For example, people with active lupus erythematosus may have lower-than-normal levels of the complement proteins C3 and C4.Autoimmune disorderAn autoimmune disorder occurs when the body's immune system attacks and destroys healthy body tissue by mistake. There are more than 80 autoimmune d...ImageRead Article Now Book Mark Article Lupus erythematosusSystemic lupus erythematosus (SLE) is an autoimmune disease. In this disease, the immune system of the body mistakenly attacks healthy tissue. It c...ImageRead Article Now Book Mark Article C3Complement C3 is a blood test that measures the activity of a certain protein. This protein is part of the complement system. The complement system ...ImageRead Article Now Book Mark Article C4Complement component 4 is a blood test that measures the activity of a certain protein. This protein is part of the complement system. The compleme...ImageRead Article Now Book Mark Article The test may also be done for the following conditions: Fungal infections Gram negative septicemia SepticemiaSepticemia is bacteria in the blood (bacteremia) that often occurs with severe infections. Also called sepsis, septicemia is a serious, life-threate...Read Article Now Book Mark Article Parasitic infections, such as malaria MalariaMalaria is a parasitic disease that involves high fevers, shaking chills, flu-like symptoms, and anemia.ImageRead Article Now Book Mark Article Paroxysmal nocturnal hemoglobinuria (PNH) Paroxysmal nocturnal hemoglobinuria (PN...Paroxysmal nocturnal hemoglobinuria is a rare disease in which red blood cells break down earlier than normal.ImageRead Article Now Book Mark Article ShockShockShock is a life-threatening condition that occurs when the body is not getting enough blood flow. Lack of blood flow means the cells and organs do n...ImageRead Article Now Book Mark Article Normal Results The normal range is 88 to 201 milligrams per deciliter (mg/dL) (0.88 to 2.01 g/L).Note: Normal value ranges may vary slightly among different laboratories. Talk to your provider 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 colitisUlcerative colitisUlcerative colitis is a condition in which the lining of the large intestine (colon) and rectum become inflamed. It is a form of inflammatory bowel ...ImageRead Article Now Book Mark Article Decreased complement activity may be seen in:Bacterial infections (especially Neisseria) Cirrhosis CirrhosisCirrhosis is scarring of the liver and poor liver function. It is the last stage of chronic liver disease.ImageRead Article Now Book Mark Article Glomerulonephritis GlomerulonephritisGlomerulonephritis is a type of kidney disease in which the part of your kidneys that helps filter waste and fluids from the blood is damaged....ImageRead Article Now Book Mark Article Hepatitis HepatitisHepatitis is swelling and inflammation of the liver.ImageRead Article Now Book Mark Article Hereditary angioedema Hereditary angioedemaHereditary angioedema is a rare but serious problem with the immune system. The problem is passed down through families. It causes swelling, partic...ImageRead Article Now Book Mark Article Kidney transplant rejection Kidney transplantA kidney transplant is surgery to place a healthy kidney into a person with kidney failure.ImageRead Article Now Book Mark Article Lupus nephritis Lupus nephritisLupus nephritis, which is a kidney disorder, is a complication of systemic lupus erythematosus.ImageRead Article Now Book Mark Article Malnutrition Systemic lupus erythematosus Rare inherited complement deficiencies Risks Risks associated with having blood drawn are slight, but may include:Excessive bleeding Fainting or feeling lightheaded Hematoma (blood accumulating under the skin) Infection (a slight risk any time the skin is broken) Considerations The complement cascade is a series of reactions that take place in the blood. The cascade activates the complement proteins. The result is an attack unit that creates holes in the membrane of bacteria, killing them. C3 attaches to bacteria and kills them directly.Open ReferencesReferencesAtkinson JP. Complement system in disease. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 44.Bean KV, Massey HD, Gupta G. Mediators of inflammation: complement. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 48.Sullivan KE, Grumach AS. The complement system. In: Burks AW, Holgate ST, O'Hehir RE, Broide DH, et al. eds. Middleton's Allergy: Principles and Practice. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 8.AllVideoImagesTogBlood test - illustration Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. Preparation may vary depending on the specific test.Blood testillustrationBlood test - illustration Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. Preparation may vary depending on the specific test.Blood testillustration Tests for Complement component 3 (C3) Complement component 3 (C3)Complement component 4Related Information Complement(Medical Test)C1 esterase inhibitor(Medical Test)Systemic lupus erythematosus(Condition)Complement component 4(Medical Test)Septicemia(Condition)Shock(Injury)Malaria(Condition)Paroxysmal nocturnal hemoglobinuria (PNH)(Condition)Ulcerative colitis(Condition)Hereditary angioedema(Condition)Systemic lupus erythematosus - InDepth(In-Depth)Ulcerative colitis - InDepth(In-Depth)Cirrhosis - InDepth(In-Depth) Review Date: 1/25/2023 Reviewed By: Neil J. Gonter, MD, Assistant Professor of Medicine, Columbia University, NY and private practice specializing in Rheumatology at Rheumatology Associates of North Jersey, Teaneck, NJ. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. 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. No warranty of any kind, either expressed or implied, is made as to the accuracy, reliability, timeliness, or correctness of any translations made by a third-party service of the information provided herein into any other language. © 1997- A.D.A.M., a business unit of Ebix, Inc. 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Complement component 3 (C3)C3Complement C3 is a blood test that measures the activity of a certain protein.This protein is part of the complement system. The complement system is a group of nearly 60 proteins that are in blood plasma or on the surface of some cells. The proteins work with your immune system and play a role to protect the body from infections, and to remove dead cells and foreign material. Rarely, people may inherit deficiency of some complement proteins. These people are prone to certain infections or autoimmune disorders.There are nine major complement proteins. They are labeled C1 through C9. This article describes the test that measures C3. How the Test is Performed Blood is drawn from a vein. Most often, a vein from the inside of the elbow or the back of the hand is used.The procedure is as follows:The site is cleaned with an antiseptic. The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood. The provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm. Once the blood has been collected, the needle is removed. The puncture site is covered to stop any bleeding.In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding. How to Prepare for the Test There is no special preparation needed. How the Test will Feel When the needle is inserted to draw blood, some people feel moderate pain. Others may feel only a prick or stinging sensation. Afterward, there may be some throbbing. Why the Test is Performed C3 and C4 are the most commonly measured complement components.A complement test may be used to monitor people with an autoimmune disorder. It is done to see if treatment for their condition is working. When the complement system is turned on during inflammation, levels of complement proteins may go down. For example, people with active lupus erythematosus may have lower-than-normal levels of the complement proteins C3 and C4.Autoimmune disorderAn autoimmune disorder occurs when the body's immune system attacks and destroys healthy body tissue by mistake. There are more than 80 autoimmune d...ImageRead Article Now Book Mark Article Lupus erythematosusSystemic lupus erythematosus (SLE) is an autoimmune disease. In this disease, the immune system of the body mistakenly attacks healthy tissue. It c...ImageRead Article Now Book Mark Article C3Complement C3 is a blood test that measures the activity of a certain protein. This protein is part of the complement system. The complement system ...ImageRead Article Now Book Mark Article C4Complement component 4 is a blood test that measures the activity of a certain protein. This protein is part of the complement system. The compleme...ImageRead Article Now Book Mark Article The test may also be done for the following conditions: Fungal infections Gram negative septicemia SepticemiaSepticemia is bacteria in the blood (bacteremia) that often occurs with severe infections. Also called sepsis, septicemia is a serious, life-threate...Read Article Now Book Mark Article Parasitic infections, such as malaria MalariaMalaria is a parasitic disease that involves high fevers, shaking chills, flu-like symptoms, and anemia.ImageRead Article Now Book Mark Article Paroxysmal nocturnal hemoglobinuria (PNH) Paroxysmal nocturnal hemoglobinuria (PN...Paroxysmal nocturnal hemoglobinuria is a rare disease in which red blood cells break down earlier than normal.ImageRead Article Now Book Mark Article ShockShockShock is a life-threatening condition that occurs when the body is not getting enough blood flow. Lack of blood flow means the cells and organs do n...ImageRead Article Now Book Mark Article Normal Results The normal range is 88 to 201 milligrams per deciliter (mg/dL) (0.88 to 2.01 g/L).Note: Normal value ranges may vary slightly among different laboratories. Talk to your provider 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 colitisUlcerative colitisUlcerative colitis is a condition in which the lining of the large intestine (colon) and rectum become inflamed. It is a form of inflammatory bowel ...ImageRead Article Now Book Mark Article Decreased complement activity may be seen in:Bacterial infections (especially Neisseria) Cirrhosis CirrhosisCirrhosis is scarring of the liver and poor liver function. It is the last stage of chronic liver disease.ImageRead Article Now Book Mark Article Glomerulonephritis GlomerulonephritisGlomerulonephritis is a type of kidney disease in which the part of your kidneys that helps filter waste and fluids from the blood is damaged....ImageRead Article Now Book Mark Article Hepatitis HepatitisHepatitis is swelling and inflammation of the liver.ImageRead Article Now Book Mark Article Hereditary angioedema Hereditary angioedemaHereditary angioedema is a rare but serious problem with the immune system. The problem is passed down through families. It causes swelling, partic...ImageRead Article Now Book Mark Article Kidney transplant rejection Kidney transplantA kidney transplant is surgery to place a healthy kidney into a person with kidney failure.ImageRead Article Now Book Mark Article Lupus nephritis Lupus nephritisLupus nephritis, which is a kidney disorder, is a complication of systemic lupus erythematosus.ImageRead Article Now Book Mark Article Malnutrition Systemic lupus erythematosus Rare inherited complement deficiencies Risks Risks associated with having blood drawn are slight, but may include:Excessive bleeding Fainting or feeling lightheaded Hematoma (blood accumulating under the skin) Infection (a slight risk any time the skin is broken) Considerations The complement cascade is a series of reactions that take place in the blood. The cascade activates the complement proteins. The result is an attack unit that creates holes in the membrane of bacteria, killing them. C3 attaches to bacteria and kills them directly.Open ReferencesReferencesAtkinson JP. Complement system in disease. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 44.Bean KV, Massey HD, Gupta G. Mediators of inflammation: complement. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 48.Sullivan KE, Grumach AS. The complement system. In: Burks AW, Holgate ST, O'Hehir RE, Broide DH, et al. eds. Middleton's Allergy: Principles and Practice. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 8.