My doctor is doing a blood test. He is an allergist.
Blood Test - What is C1?
Question posted by lvblonde33 on 9 Nov 2012
Last updated on 9 November 2012
He was testing the blood for C1. I had an allergic reaction to my medication and my throat swelled and had problems breathing I was wonderig what this test is for.
Welcome to the site.
C1 esterase inhibitor (C1-INH) is a protein found in the fluid part of your blood that controls C1, the first component 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.
Complement factors are very important in testing for autoimmune diseases, especially systemic lupus erythematosus. C1-INH is an important marker for hereditary angioedema, and it also plays a role in other diseases.
How the Test is Performed
Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (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.
Next, the health care 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, and 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
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.
Why the Test is Performed
Your doctor may order this test if you have signs of hereditary angioedema. Hereditary angioedema is caused by low levels of C1-INH.
C1 esterase inhibitor: 16 to 33 milligrams per deciliter (mg/dL).
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
Abnormal results may be due to certain types of angioedema.
Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining blood from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight but may include:
Fainting or feeling light-headed
Hematoma (blood accumulating under the skin)
Infection (a slight risk any time the skin is broken)
C1 inhibiting factor; C1-INH
SOURCE: U.S. National Library of Medicine
All the best,
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