Anyone else have a high complement C3 blood test?

Posted by katrina123 @katrina123, May 20 9:51am

I recently had some tests and I received a letter to call my doctor's office because I have a high compliment c3 blood test.

Have any of you had this and what did it mean for you?

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I’m wondering what symptoms prompted your Dr to order this test. Have you felt sick in any way? There are a number of disorders that can cause C3 to be elevated. Some are not serious, some are, so this will need to be investigated as to cause. C3&4 are related to inflammation so some autoimmune inflammatory diseases can cause high or low levels. Your Dr will connect your symptoms with the lab results and order more tests accordingly. Let us know what is found. We all learn from each other! Good luck.


Hi @katrina123, a C3 complement blood test provides information about your immune system. You can read more about it here:
- C3 Complement Blood Test

Like @slkanowitz, I'd be interested to know what prompted the ordering of further blood tests. Did you have the test already?


I had a severe cold virus that lasted several weeks with a bout of explosive bloody diarrhea, then an acute conjunctivitis. Then I had to have Mohs surgery for basal cell carcinoma on my face. Then I had a colonoscopy with 2 premalignant adenomas, and one was a large villous type. Unfortunately, the large adenoma bled a lot when it was removed so they had to place a hemoclip in my colon to stop the bleeding. Also, in Jan I had a lumpectomy and in Feb I had 4 weeks of radiation.
I have a primary immune disease CVID so my doctor was concerned. I still don't know very much more about this C3 test. I was concerned about the letter that I received so I contacted my doctor. Her nurse ended up telling me not to be too concerned and they could redo the test in 6 months. They thought maybe the numbers were elevated due to everything that my body had gone through in the last 5 months.

(Not sure if it was not that important why they went out of their way to mail me a letter.)

I will ask for another blood test in 6 months.

Worrying about a hemoclip in my colon for my next MRI is a whole new issue.

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