Why is C4 low in hereditary angioedema?

Why is C4 low in hereditary angioedema?

If a C4 level is found to be low or clinical suspicion of hereditary or acquired angioedema is high, testing of C1-inhibitor (INH) level and function is warranted. C4 levels are often low due to improper handling; therefore, repeating a C4 level when further testing is performed is also advisable.

How do you get acquired angioedema?

Acquired angioedema occurs when levels of a protein called C1-inhibitor (C1-I) are too low. This protein blocks the activity of two other proteins; plasma kallikrein and coagulation factor 12. These two proteins are important for blood clotting, inflammation, and wound healing.

How does C1 esterase deficiency cause angioedema?

C1 esterase inhibitor deficiency, also known as hereditary angioedema, results in the unchecked production of the vasodilator bradykinin.

Is hereditary angioedema an autoimmune disease?

Hereditary angioedema may be associated with autoimmune diseases, such as systemic lupus erythematosus, rheumatoid arthritis, autoimmune thyroiditis and glomerulonephritis.

What does it mean if I have a low C4?

A low level of C4 is associated with autoimmune diseases, such as lupus and rheumatoid arthritis. The complement C4 test only requires basic preparation and carries few risks. The sample of your blood will be sent to a laboratory for analysis. The results will then be sent to your doctor.

What is angioedema caused by?

Angioedema is often the result of an allergic reaction. This is where the body mistakes a harmless substance, such as a certain food, for something dangerous. It releases chemicals into the body to attack the substance, which cause the skin to swell.

How is acquired angioedema treated?

Angioedema prophylaxis is performed using antifibrinolytic agents and attenuated androgens with antifibrinolytic agents providing somewhat better results. Treatment of the associated disease can resolve AAE in some patients.

What are the signs and symptoms of angioedema?


  • Welts that form in minutes to hours.
  • Swelling and redness, especially around the eyes, cheeks or lips.
  • Pain or warmth in the affected areas.