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Doctor insights on: Complement Levels

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Dr. Walter Husar
19 doctors shared insights

Complement Levels (Overview)

Total complement activity (CH50, CH100) looks at the overall activity of the complement system. Typically, other tests that are more specific for the suspected disease are performed first. C3 and C4 are the most commonly measured complement components. A complement test may be used to monitor patients with an autoimmune disorder and to see if treatment for their condition is working. For example, patients with active lupus erythematosus may have lower-than-normal levels of the complement proteins C3 and C4.


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What do low complement levels indicate is going on?

What do low complement levels indicate is going on?

Some things: To consider: 1) autoimmunity (particularly sle) 2) immunodeficiency 3) blood dyscrasia or cancer. ...Read more

Dr. Walter Husar
19 doctors shared insights

Complement Levels (Overview)

Total complement activity (CH50, CH100) looks at the overall activity of the complement system. Typically, other tests that are more specific for the suspected disease are performed first. C3 and C4 are the most commonly measured complement components. A complement test may be used to monitor patients with an autoimmune disorder and to see if treatment for their condition is working. For example, patients with active lupus erythematosus may have lower-than-normal levels of the complement proteins C3 and C4.


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I've never head of complement levels, what do they mean when they are low?

I've never head of complement levels, what do they mean when they are low?

Complement: Complement are proteins in the blood that are part of the immune system. Individuals with very low or absent complement are prone to infections such as recurrent neisseria meningitis. If the blood test isn't put on ice right after it is drawn, then a low level could result that is incorrect. ...Read more

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I have normal levels of complement C2 and c4. C3 level is low. Ch50 is high-normal(57 u/ml)-(all are serum tests)-what are the possible causes?

I have normal levels of complement C2 and c4.  C3 level is low.  Ch50 is high-normal(57 u/ml)-(all are serum tests)-what are the possible causes?

Labwork: Proper medicine would be not to treat lab values but the patient. Based on the lab values you provided it is impossible to suggest any kind of diagnosis. We would need to know your presentation and other labwork that was done in order to help you sort it out. ...Read more

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What would having low complement levels indicate?

What would having low complement levels indicate?

Low complement: Low levels of complement are seen in persons with complement deficiency who are prone to recurrent infections as well as in certain autoimmune conditions, inherited angioedema conditions, and hives associated with vasculitis (inflammed blood vessels). These can all be serious. Collection of blood to measure complement is tricky and needs to be done right or low level could occur. ...Read more

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What do low complement levels indicate is going on?

Some things: To consider: 1) autoimmunity (particularly sle) 2) immunodeficiency 3) blood dyscrasia or cancer. ...Read more

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I've never head of complement levels, what do they mean when they are low?

Complement: Complement are proteins in the blood that are part of the immune system. Individuals with very low or absent complement are prone to infections such as recurrent neisseria meningitis. If the blood test isn't put on ice right after it is drawn, then a low level could result that is incorrect. ...Read more

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Should I see a rheumatologist if I have elevated complement levels?

Should I see a rheumatologist if I have elevated complement levels?

Don t think so: Complement is an acute phase reactantant , having high complement levels only means there is a reaction , probably inflammatory . If the diagnosis is ulcerative colitis , but you don t have arthritis youndont need to see the rheumatologist for high complement leves. ...Read more

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I have vesico-ureteric reflux and acute hypertension, why would complement levels be an investigation?

See Below: Most likely they are looking to see if your body is attacking your kidneys by activating complement proteins in the kidney tissue. If there is complement deposition there then the explanation for your hypertension may be injury to your kidneys from this. ...Read more

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Can low complement levels cause lichen planus ( armpit) and tinea versicolor?

Can low complement levels cause lichen planus ( armpit) and tinea versicolor?

Yes and no: Tinea versicolor is a fungal infection. It may present due to a decrease in the immune system (low complement). Lichen planus is an autoimmune disorder of unknown origin. Various autoimmune illnesses are associated with increased incidence in lichen planus. Secondary raynaud's disease also has been linked with some autoinmune disorders such as lupus, rheumatoid arthritis and sjogren's syndrome. ...Read more

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Can you have lupus with completely normal bloodwork? ANA, ENA neg, Complement levels normal, CBC normal. ESR of 2 and normal CRP

Can you have lupus with completely normal bloodwork? ANA, ENA neg, Complement levels normal, CBC normal. ESR of 2 and normal CRP

ANA negative lupus: There is an entity called ANA negative lupus. Please visit this site for diagnostic criteria for SLE. From what you have described, it is unlikely that you have lupus. http://www.lupusresearchinstitute.org/lupus-facts/lupus-diagnosis ...Read more

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Have borderline low C3 and C4 complement levels and low 1:80 titre positive ANA speckled. With symptoms relating to sle and sjorgrens - atypical ?

Have borderline low C3 and C4 complement levels and low 1:80  titre positive ANA speckled. With symptoms relating to sle and sjorgrens - atypical ?

Atypical for what?: Rheumatic disease generally requires a cluster of suggestive symptoms which is supported by lab studies. I do not know your symptoms, but your labs are not particularly suggestive of anything. ...Read more

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My C4 complement level is low and C3 complement is at the low end of the range (90, ref range 90-180). What could this mean?

May be significant : Low Complement levels may be nonspecific markers for autoimmune disorders. Other symptoms and clinical findings are needed to be able to adequately answer your question. ...Read more

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My 4 yo son recently had some bloodwork done. C4 complement level was 14, C3 complement was 148. Risk for autoimmune disease? C4 is just barely normal

My 4 yo son recently had some bloodwork done. C4 complement level was 14, C3 complement was 148. Risk for autoimmune disease? C4 is just barely normal

No: And depends on history, physical exam and why the test was ordered. Auto immune disorders are vast, not a single blood test result makes the diagnosis, which is rather a complex one. Ask your doctor about the result and the logic behind ordering the test, wish you and your son wellness ...Read more

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41 year-old woman having lupus-like symptoms, angioedema and low complement levels.....?

41 year-old woman having lupus-like symptoms, angioedema and low complement levels.....?

Lupus: This sounds like a diagnosis of lupus. Finish and additional work up and be seen by a rheumatologist and.other needed sub specialist. All the best. ...Read more

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Labcorp says that a serum complement C3 level of 89 mg/dl is low for an adult. Does this sound right?

Maybe, maybe not: Complement levels are only relevant in the clinical setting. Though 89 may be borderline low, it may be irrelevant as the "normal" range is an approximation. On the other hand, if the complement level is steadily falling from one test to the next in a patient with known systemic lupus, it may be relevant. Remember that lupus cannot be diagnosed by complement levels or a positive ANA alone. ...Read more

Complement (Definition)

The complement system is an important effector mechanism of both humoral and innate immunity. Its functions are to promote phagocytosis of microbes, to stimulate inflammation, and to induce lysis of these organisms. The system is highly complex and comprised of over 50 effector and regulatory molecules. It is activated via one of three pathways: antibody, lectin, or by ...Read more