C3 and C4 are part of the body's compliment system. The complement system is one of the natural
defense mechanisms that protects the human body from infections and perhaps tumors. A measurement of complement components assists doctors in the diagnosis of immunologic disorders (such as Lupus), especially those associated with deficiencies of complement components.
Persons with abnormal complement levels usually fall into one of four categories: 1) multisystem rheumatic disease such as systemic lupus erthematosus (SLE), 2) glomerulonephritis; 3) hemolytic
anemia or, 4) recurrent or overwhelming infections.
Decreased C3 is usually indicative of auto-immune disorders (like Lupus). Increased levels of both C3 and C4, in addition to increased concentrations of C-Reactive Protein, are indicative of acute inflammatory disease and tissue inflammation.
Mixed Connective Tissue Disease (MCTD) is an autoimmune disorder that has overlapping symptoms, usually of three connective tissue diseases — lupus, scleroderma and polymyositis. Mixed connective tissue disease also may have features of rheumatoid arthritis. For this reason, mixed connective tissue disease is sometimes referred to as an overlap disease. Symptoms of these diseases usually don't appear all at once, which makes the diagnosis quite difficult. People with mixed connective tissue disease often are eventually diagnosed with lupus and/or a Lupus diagnosis is often changed to MCTD. MCTD commonly causes: joint pain/swelling, malaise (general all over sickness), Raynaud phenomenon,
Sjögren's syndrome, muscle inflammation, and sclerodactyly (thickening of the skin of the pads of the fingers).
Because many symptoms of systemic lupus erythematosus (SLE) mimic those of other illnesses, lupus can be a difficult disease to diagnose. There are three primary factors that doctors consider when attempting to diagnose Lupus: 1) Your entire medical history 2)The results and analysis of your laboratory tests 3) The results and analysis of specialized tests related to auto-immune diseases.
To make a diagnosis of SLE, an individual must have evidence of a multi-system disease (i.e. has shown abnormalities in several different organ systems). Typical symptoms or signs that might lead to suspicion of SLE are:
* Skin: Butterfly rash across the cheeks; ulcers in the mouth; hair loss.
* Joints: Pain; redness, swelling.
* Kidney: Abnormal urinalysis suggesting kidney disease.
* Lining membranes: Pleurisy (inflammation of the lining of the lung); pericarditis (inflammation of the heart lining); and/or peritonitis (inflammation around the abdomen). Taken together, these types of inflammation are known as polyserositis.
* Blood: Hemolytic anemia (the red cells are destroyed by autoantibodies); leukopenia (low white blood cell count); thrombocytopenia (low number of platelets).
* Lungs: Infiltrates (shadowy areas seen on a chest x-ray) that come and go
* Nervous system: Convulsions (seizures); psychosis; nerve abnormalities that cause strange sensations or alter muscular control or strength.
If you have several of these symptoms, then your doctor will usually order a series of tests to examine how well your immune system is functioning. In these tests, the doctors will be looking for evidence of auto-antibodies. Please know that there is no one test that can definitely say whether or not you have lupus. In fact, there are many laboratory tests which help your doctor to make a lupus diagnosis.
The routine clinical tests which doctors will use and that may suggest that you may have active systemic disease include:
* sedimentation rate (ESR) and CRP (C-reactive protein) binding, both of which are frequently elevated if there is inflammation in the body from any cause.
* serum protein electrophoresis which may reveal increased gammaglobulin and decreased albumin (Proteins are the most abundant compounds in your serum (the rest of your blood when you remove all the cells). Amino acids are the building blocks of all proteins. In turn proteins are the building blocks of all cells and body tissues.The major measured serum proteins are divided into two groups, albumin and globulins. There are four major types of globulins, each with specific properties and actions. A typical blood panel will provide four different measurements - the total protein, albumin, globulins, and the albumin globulin ratio. Optimal Range: 7.2-8.0 g/100ml)
* routine blood counts which may reveal anemia and low platelet and white cell counts
* routine chemistry panels which may reveal kidney involvement by increases in serum blood urea nitrogen and creatinine
* abnormalities of liver function tests
* increased muscle enzymes (such as CPK) if muscle involvement is present.
These kinds of abnormalities alert the doctor to the presence of a systemic disease with multiple organ involvement.
Commonly used blood tests in the diagnosis of SLE are:
* Anti-nuclear antibody test (ANA) to determine if autoantibodies to cell nuclei are present in the blood
* Anti-DNA antibody test to determine if there are antibodies to the genetic material in the cell
* Anti-Sm antibody test to determine if there are antibodies to Sm, which is a ribonucleoprotein found in the cell nucleus
* Serum (blood) complement test to examine the total level of a group of proteins which can be consumed in immune reactions
* Complement proteins C3 and C4 test to examine specific levels of inflammation.
Please be aware that no one test is used to confirm or deny any diagnosis. All tests (blood & clinical) are used in conjunction with each other, your symptomology, and your medical history to arrive at a possible diagnosis.
I realize that this is a lot of information, however I hope that you found it helpful. Please let us know if you need anything further. We are here to help you in any way that we can.
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