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Complement Levels And Lupus

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Why it is done:
this test is done to monitor the level of activity in lupus as well as to aid in lupus diagnosis.

How it is done:
this test requires a blood sample to be taken usually from the arm.

What is the complement system:
the complement system is a set of blood proteins that are circulating, acting as mediators of the body's inflammatory response. They act especially in the destruction of viruses and bacteria. The complement system does not require previous exposure to a microorganism like antibodies do. It also does not keep a memory of encounters the way antibodies do. Antibodies also need time to be generated, the complement system does not. For these reasons the complement system is a very important part of the immune system and imbalances can adversely affect the integrity and function of the immune system.

What the test measures:
c3 and c4 are the most commonly measured complement compounds. Ch50 and ch100 (total complement activity) will be measured if your doctor suspects deficiency that is not measured by c3 or c4.

How the test is used to monitor lupus activity:
since the complement system is used by the body to help clear immune complexes from the blood, it can be used to monitor activity in lupus, particularly with glomerulonephritis and vasculitis.

Normal levels:
normal levels vary based on a number of factors including gender, age, and the lab doing the testing. Here is a basic guideline:
c3 - males: 88 to 252 mg/dl (880 to 2520 mg/l)
females: 88 to 206 mg/dl (880 to 2060 mg/l)
c4 - males: 12 to 72 mg/dl (120 to 720 mg/l)
females: 13 to 75 mg/dl (130 to 750 mg/l)

what low levels mean:
low complement levels in lupus usually mean increased disease activity. When the body uses the complement system to clear immune complexes from the blood it results in low complement levels. The complement proteins are not produced as quickly as they are being used.
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replied March 17th, 2009
Antilphoslipid antibody syndrome and low c3 c4 levls
I have tested positive once only for antiphospholipid antibody sydrome. I have had 5 miscarriges and one live birth at 24 weeks only because I was taking fragmin. I have had a complete blood workup done and now am told I have low c3 and c4 complement levels. I get sick all of the time and it usually takes me longer than normal to recover. What does this all mean and is the antiphospholipid antibody syndrome and low c3 c4 complement levels all related. I am only 38 and am trying to have another baby. Any feedback would be appreciated.
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replied April 24th, 2009
Check for Lupus
If you have not been evaluated for Lupus, I strongly suggest you talk to your doctor about it. APS syndrome and low complement levels are both common in Lupus.
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replied March 25th, 2010
Low C3 C4 complement levels,what does this mean?
I have been tested for lupus and it was negative. Can lupus results come back negative and then positive if you are re tested down the road? Yet I continue to get sick. In the last 9 months I have had three colds with this last one leading to a viral pnemonia. I also recently cut my arm, 2 of the stiches popped and I ended up getting an infection in my arm that required IV Vancomycin for a week. I am so tired of always getting sick and feeling tired all of the time. I have had two failied IVF cycles, numerous failed IUI's, 5 miscarriges, and the doctors at the fertility clinic say my eggs are old and just aren't responding well to the drugs. I have also tested mildly positive once to anti phospho lipid anti body syndrome. My last pregnancy that I did manage to carry to 24 weeks was because I was taking baby aspirin and fragmin.

I have gotten a re referrel to the Dr. that did my workup on me before and checked for lupus, and he was the one that told me my c3 c4 complent levels were low. He tested them twice and both times they were low. All he could tell me was that I was immune comprimised and he did not know why?

I am due to go in for ivf egg donor in the summer time but I want to see this specialist again and have another blood workup done prior to doing the ivf egg donor.

If anyone has any suggestioins or information for me please write me directly.

Thank you
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replied October 26th, 2010
Hello i need help the dr, got some blood from me and made some test and i came out positive for lupus but its only 1.40 % is that bad do i have to see a specialist help me someone i dont want to have it i have 2 small girls.
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