Complement Component C3c and C4c

The Complement Component C3c and C4c test contains 1 test with 2 biomarkers.

Brief Description: The Complement Component C3c and C4c test is a laboratory procedure used to measure the levels of specific proteins—C3c and C4c—in the blood. These proteins are part of the complement system, a group of proteins that play vital roles in immunity and inflammation. The complement system enhances (or complements) the body's ability to clear pathogens and damaged cells.

Also Known As: C3 and C4 Test, Complement C3 and C4 Test, Complement Test

Collection Method: Blood Draw

Specimen Type: Serum

Test Preparation: No preparation required

When is a Complement Component C3c and C4c test ordered?

When a person exhibits inexplicable edema, inflammation, or indications of an autoimmune condition like SLE, complement testing may be mandated. It may also be requested when a medical professional wants to assess the complement system of a patient who they suspect may have an immune complex-related disease.
When the total complement activity is abnormal, individual complement components may be ordered to help identify which ones are lacking or defective. The most usually prescribed levels are C3 and C4, however when additional shortages are detected, other levels, such C1 inhibitor, may also be required. Because the relative levels are frequently significant, C3 and C4 are frequently ordered together.
Complement testing may be used to provide a general assessment of the severity of an acute or chronic ailment after a diagnosis, with the underlying supposition that the severity is related to the decline in complement levels. When a doctor wishes to track the progression of a problem, they could occasionally order complement testing.

What does a Complement Component C3c and C4c blood test check for?

More than 30 circulating blood proteins make up the intricate complement system, which functions to support inflammatory and immunological responses. Its main function is to eliminate invading infections like viruses and bacteria. When the body produces antibodies against its own tissues that it misinterprets as foreign, the complement system can also be activated. The amount or activity of complement proteins in the blood is measured by complement assays.

A component of the body's innate immune system is the complement system. The innate immune system is non-specific and rapid to react to external molecules, in contrast to the acquired immune system, which generates antibodies that target and defend against specific threats. It does not require prior exposure to an invasive drug or bacterium and does not keep track of prior interactions.

The primary complement proteins are numbered C1 through C9. There are nine of them. Together with the remaining proteins, these elements form complexes that react to infections, non-self tissues, dead cells, and inflammation by activating, amplifying, breaking apart, and generating cascades.

There are numerous strategies to start complement activation. These are known as lectin, alternative, or classical routes. However, the development of the membrane attack complex is the common result of all activation mechanisms. Several things happen as a result of complement activation:

• Each pathogen or aberrant cell that has been selected for eradication adheres to the surface thanks to the MAC. It produces lysis, or the demise of the cell by letting the contents out, much like puncturing a water-filled balloon, by creating a lesion in the membrane wall.
• It makes blood arteries more permeable, enabling white blood cells to go from the bloodstream and into the tissues to fight infections.
• WBCs are drawn to the infection site by it.
• It promotes the killing of germs by macrophages and neutrophils during phagocytosis, a process.
• It makes immune complexes more soluble and aids in their removal from the circulation.

The amount or activity of complement proteins in the blood is measured by complement assays. To ascertain whether the system is operating normally, complement components might be examined individually or collectively. The two complement proteins that are most routinely tested are C3 and C4. If a medical professional suspects a shortfall that cannot be detected by C3 or C4, total complement activity can be assessed. The function of the entire C1–C9 classical complement pathway is evaluated by CH50. Each of the nine complement levels can be measured separately to check for inherited or acquired deficits if this reading is outside the usual range.

Lab tests often ordered with a Complement Component C3c and C4c test:

When C3c and C4c are ordered, they are usually part of a broader evaluation of immune system function. Here are some tests commonly ordered alongside them:

1. Total Complement Activity (CH50):

   • Purpose: To measure the overall activity of the classical complement pathway.
   • Why Is It Ordered: To assess the integrity and functional capacity of the complement system as a whole. A decrease in CH50 can indicate consumption or deficiency of complement components.

2. Erythrocyte Sedimentation Rate (ESR) and C-Reactive Protein (CRP):

   • Purpose: To measure markers of inflammation in the body.
   • Why Is It Ordered: To assess systemic inflammation, which can be associated with conditions that affect complement levels.

3. Antinuclear Antibody testing:

   • Purpose: To detect specific autoantibodies associated with systemic lupus erythematosus (SLE) and other connective tissue diseases.
   • Why Is It Ordered: To help diagnose and characterize specific autoimmune conditions, which often involve abnormal complement levels.

4. Kidney Function Test:

   • Purpose: To assess kidney function.
   • Why Is It Ordered: To evaluate kidney health, as kidney involvement is common in diseases like lupus, which can also affect complement levels.

5. Urinalysis with Microscopy:

   • Purpose: To analyze various components of the urine.
   • Why Is It Ordered: To check for proteinuria, hematuria, or other abnormalities that might indicate kidney disease, often associated with systemic diseases involving complement.

6. Liver Function Test:

   • Purpose: To assess liver health.
   • Why Is It Ordered: To evaluate liver function, as the liver is a major site of complement synthesis.

7. Rheumatoid Factor (RF) and Anti-CCP (Cyclic Citrullinated Peptide) Antibody:

   • Purpose: To detect antibodies often associated with rheumatoid arthritis.
   • Why Is It Ordered: To assess for rheumatoid arthritis, which can sometimes be associated with changes in complement levels.

These tests, when ordered alongside Complement C3c and C4c, provide a comprehensive evaluation of the immune system and help in diagnosing and monitoring autoimmune and inflammatory disorders. They are crucial for understanding the underlying cause of abnormal complement levels and guiding appropriate treatment. The specific combination of tests will depend on the individual’s symptoms, clinical presentation, and medical history.

Conditions where a Complement Component C3c and C4c test is recommended:

The primary conditions that could necessitate this test include:

• Systemic Lupus Erythematosus (SLE): An autoimmune disorder where the body's immune system attacks its own tissues. Decreased C3c and C4c levels can be seen in active SLE.

• Glomerulonephritis: Inflammation of the tiny filters in the kidneys. The complement system might be activated in certain types of glomerulonephritis.

• Hereditary angioedema: A genetic disorder that can cause episodes of swelling and can be linked to complement proteins.

• Other autoimmune disorders: Such as rheumatoid arthritis, where complement proteins may be involved.

How does my health care provider use a Complement Component C3c and C4c test?

To ascertain whether shortages or anomalies in the complement system are the root cause of, or contribute to, a person's sickness or condition, complement assays, most frequently C3 and C4, are utilized.

What do my Complement Component C3c and C4c test results mean?

Increased consumption or, less frequently, a congenital deficit, can cause complement levels to drop. A high incidence of recurrent microbial infections is typically caused by a hereditary defect in one of the complement proteins. Reduced complement levels are linked to a higher risk of autoimmune disease development. While C3 alone is often low in septicemia and diseases brought on by fungus or parasites, like malaria, C3 and C4 levels are typically both decreased in SLE.
Complement levels will typically return to normal if the underlying acute or chronic ailment can be treated if the deficiency is brought on by one of these.

Complement activity may be reduced with:

• Hepatitis
• Cirrhosis
• Malnutrition
• Septicemia
• Kidney Disease
• Lupus
• Angioedema
• Rheumatoid Arthritis

During acute or chronic inflammation, complement protein levels typically rise together with those of other unrelated proteins known as acute phase reactants. When the underlying illness is treated, all of these often return to normal. Comparatively to the frequently ordered C-reactive protein, complement proteins are less frequently measured in these circumstances, hence the value of their measurement in these circumstances is not discussed here.

Increased complement activity include can be seen with:

• Juvenile Rheumatoid Arthritis
• Thyroiditis
• Sarcoidosis
• Cancer
• Ulcerative Colitis
• Acute Myocardial Infarction

Most Common Questions About the Complement Component C3c and C4c test:

Purpose and Indications for the Complement Component C3c and C4c Test

Why is the Complement Component C3c and C4c test ordered?

The Complement Component C3c and C4c test is primarily ordered when a doctor suspects that a patient has an immune system disorder or an autoimmune disease. These complement proteins play crucial roles in the immune response, and alterations in their levels can indicate various conditions, including lupus or kidney diseases like glomerulonephritis.

What does the Complement Component C3c and C4c test help diagnose?

The test helps diagnose conditions associated with abnormal complement activity. Low levels of C3c and C4c can suggest conditions like Systemic Lupus Erythematosus (SLE), while elevated levels might indicate acute inflammatory conditions.

Interpreting the Results

What do decreased levels of C3c and C4c in the test indicate?

Decreased levels of C3c and C4c often suggest the presence of an autoimmune disorder, such as lupus. It can also indicate certain types of kidney diseases or infections. In autoimmune diseases, the immune system consumes more of these complement components, leading to their decreased levels in the blood.

What do increased levels of C3c and C4c suggest?

Elevated levels of C3c and C4c are less common and can indicate that the body is in an acute inflammatory state. It may also point towards certain conditions where complement activation is ongoing, but not due to autoimmune activity.

Follow-up and Treatment

How are results from the Complement Component C3c and C4c test used in treatment planning?

The results provide insight into the activity of the immune system. If decreased levels are found, it may suggest the need for immunosuppressive therapies, particularly in autoimmune diseases. Conversely, if elevated levels are noted, anti-inflammatory treatments might be considered.

Disease Monitoring and Complications

How frequently should the Complement Component C3c and C4c test be repeated for patients with autoimmune diseases?

For patients with diagnosed autoimmune diseases, monitoring complement levels can be crucial. The frequency of testing depends on the specific condition and its severity, but it's generally conducted periodically to assess disease activity and response to treatment.

Can complement levels return to normal after treatment?

Yes, with effective treatment, complement levels can return to within the normal range. Monitoring these levels can be a valuable indicator of treatment efficacy and disease remission.

Additional Information

Why might a doctor order other complement tests along with the Complement Component C3c and C4c test?

The complement system consists of various proteins that interact in complex ways. By testing multiple components, a doctor can gain a more comprehensive view of the system's activity and better pinpoint specific issues or disorders.

Are there any conditions where both high and low levels of C3c and C4c are seen?

Yes, certain conditions might show fluctuating levels of complement components. For example, in some stages of lupus, levels might be decreased due to consumption by immune complexes, while in others, inflammation might lead to increased production and elevated levels.

We advise having your results reviewed by a licensed medical healthcare professional for proper interpretation of your results.