Name of the Procedure:

Complement; functional activity, each component (also known as Complement Function Assay)

Summary

In simple terms, this procedure measures the activity of different components of the complement system, which is part of the immune system. It assesses whether each component is functioning properly to help diagnose immune-related conditions.

Purpose

This test is primarily used to investigate unusual immune system activity, infections, and autoimmune disorders. The expected outcomes are accurate diagnosis of deficiencies or dysfunctions in the complement system to guide treatment plans.

Indications

• Recurrent bacterial infections
• Autoimmune diseases (e.g., Systemic Lupus Erythematosus)
• Unexplained inflammation
• Suspected hereditary complement deficiencies

Preparation

• Patients may be instructed to fast for a few hours before the test.
• They should inform their healthcare provider about all medications and supplements they are taking, as some may need to be temporarily paused.
• No specific diagnostic tests are required beforehand, but previous blood tests might be reviewed.

Procedure Description

1. A healthcare worker will draw a blood sample from a vein in the patient's arm.
2. The blood sample is then sent to a laboratory where various complement components (like C3, C4) are tested for their functional activity.
3. Advanced laboratory techniques, such as ELISA or hemolytic assays, are used to assess the activity levels.
4. No anesthesia or sedation is needed.

Duration

The blood draw itself takes about 5-10 minutes. Lab processing may take a few days.

Setting

The blood draw is typically performed in an outpatient clinic or a laboratory.

Personnel

• Phlebotomist or nurse for drawing blood
• Laboratory technicians for processing the sample
• Immunologist or pathologist for interpreting the results

Risks and Complications

• Common: Minor pain or bruising at the needle site
• Rare: Infection, dizziness, or fainting

Benefits

The main benefit is an accurate diagnosis of complement deficiencies or dysfunctions, leading to better-targeted treatments. Results are usually available within a week.

Recovery

• There are no specific recovery steps required; patients can resume normal activities immediately.
• Keep the bandage on for at least 30 minutes to prevent bleeding.
• Follow-up appointments may be scheduled to discuss results.

Alternatives

• Total hemolytic complement (CH50) test, which measures the overall activity of the complement system.
• Genetic testing for known complement deficiencies.
• Pros: These tests may provide more comprehensive or faster results.
• Cons: They may not pinpoint dysfunction in specific complement components.

Patient Experience

• During: Brief discomfort or pinch during the blood draw.
• After: Minor tenderness or bruising at the needle site; otherwise, normal activities can be resumed without any significant pain or discomfort.
• Pain management: Over-the-counter pain relievers can be taken if necessary, but usually, no pain mitigation is needed.