Main AHCA Website

AHCA’s main website for information on Medicaid, Health Quality Assurance and the Florida Center for Health Information and Policy Analysis.

Go >

Florida Health Information Network

This website provides information and resources relating to AHCA’s initiatives for Health Information Technology and Health Information Exchange.

Go >


FloridaHealthFinder.gov

Provides health education and information to compare and locate health care providers in Florida to make well-informed health care decisions.

Go >
AHCA Network of Websites

Health Education


Health Encyclopedia

Search the Health Encyclopedia

C1 esterase inhibitor

Definition

C1 esterase inhibitor (C1-INH) is a protein found in the fluid part of your blood. It controls a protein called C1, which is part of the complement system. This 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. Low levels of C1-INH can lead to a condition called angioedema. Angioedema results in sudden swelling of the tissues of the face, upper throat and tongue and may cause difficulty breathing. Swelling in the intestine and abdominal pain may also occur. There are two types of conditions that cause angioedema from decreased levels of C1-INH. They are known as hereditary and acquired C1-INH deficiency.

This article discusses the test that is done to measure the amount of C1-INH in your blood.

Alternative Names

C1 inhibiting factor; C1-INH

How the Test is Performed

A blood sample is needed. This is most often 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.

Why the Test is Performed

You may need this test if you have signs of hereditary or acquired angioedema. Both forms of angioedema are caused by low levels of C1-INH.

Normal Results

Normal value ranges may vary slightly among different laboratories. Your health care provider will also measure the functional activity level of your C1 esterase inhibitor. Talk to your provider about the meaning of your specific test results.

What Abnormal Results Mean

Low levels of C1-INH may cause certain types of angioedema.

Risks

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

Bowen T, Cicardi M, Farkas H, et al. 2010 International consensus algorithm for the diagnosis, therapy and management of hereditary angioedema. Allergy Asthma Clin Immunol. 2010;6:24. PMID: 20667127 www.ncbi.nlm.nih.gov/pubmed/20667127.

Sullivan KE, Grumach AS. The complement system. In: Adkinson NF, Bochner BS, Burks AW, et al, eds. Middleton's Allergy: Principles and Practice. 8th ed. Philadelphia, PA: Elsevier Saunders; 2013:chap 6.

Review Date:1/20/2015
Reviewed By:Gordon A. Starkebaum, MD, Professor of Medicine, Division of Rheumatology, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, 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. Call 911 for all medical emergencies. 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

The Agency for Health Care Administration (Agency) and this website do not claim the information on, or referred to by, this site is error free. This site may include links to websites of other government agencies or private groups. Our Agency and this website do not control such sites and are not responsible for their content. Reference to or links to any other group, product, service, or information does not mean our Agency or this website approves of that group, product, service, or information.

Additionally, while health information provided through this website may be a valuable resource for the public, it is not designed to offer medical advice. Talk with your doctor about medical care questions you may have.

Health
Outcome Data

No data available for this condition/procedure.

Images

Health Encyclopedia

More Features

We Appreciate Your Feedback
1. Did you find this information useful?
         Yes
         No

2. Would you recommend this website to family and friends?
         Yes
         No