Name of the Procedure:

Complement; Total Hemolytic (CH50) Assay

Summary

The CH50 assay is a blood test that measures the overall activity of the complement system, which is part of the immune system. It helps to determine whether the complement system is working properly by measuring its ability to lyse (break down) red blood cells.

Purpose

The CH50 test is used to diagnose immune system disorders, to evaluate the integrity of the complement system, and to monitor diseases that affect complement activity. It helps to identify deficiencies in complement components that can lead to increased susceptibility to infections and autoimmune diseases.

Indications

• Recurrent bacterial infections
• Autoimmune diseases (e.g., Lupus, Rheumatoid Arthritis)
• Unexplained inflammation
• Angioedema (swelling under the skin)
• Monitoring known complement disorders

Preparation

• No fasting is required.
• Patients may need to inform their doctor about any medications they are currently taking as some drugs may affect the test results.
• A simple blood draw is performed, so wearing a short-sleeved shirt can be helpful.

Procedure Description

1. A blood sample is drawn from a vein, usually in the arm.
2. The sample is sent to a laboratory where the serum is separated from the blood cells.
3. The serum is then tested to measure its ability to cause lysis of sheep red blood cells.
4. This involves adding the serum to a solution with red blood cells and observing the degree of hemolysis.
5. Hemolysis is quantified and reported as the CH50 value.

Tools/Equipment:

• Needle and syringe or a phlebotomy set
• Blood collection tube
• Laboratory equipment for serum separation and hemolysis assessment

Anesthesia/Sedation:

• Not applicable (only a simple blood draw).

Duration

The blood draw typically takes about 5-10 minutes. Laboratory analysis might take several hours to a few days, depending on the hospital or clinic.

Setting

The blood sample is collected in an outpatient clinic or laboratory setting.

Personnel

• Phlebotomist (for blood draw)
• Laboratory technician/technologist (for sample analysis)
• Pathologist or Immunologist (for interpreting the results)

Risks and Complications

• Minor risks associated with blood draw: bruising, bleeding, or infection at the puncture site.
• Rarely, patients may feel faint or dizzy during the blood draw.

Benefits

• Identifies complement system deficiencies.
• Aids in diagnosing and monitoring autoimmune and immune system disorders.
• Helps in tailoring appropriate treatments for immune-related conditions.

Recovery

• No recovery time is needed.
• Patients can resume normal activities immediately after the blood draw.
• Follow-up with the healthcare provider for results interpretation and further management.

Alternatives

• Specific complement component assays (e.g., C3, C4 tests) measure individual complement proteins but do not provide an overall measure of the complement system function.
• Autoantibody tests can help diagnose specific autoimmune diseases.
• Pros of CH50: Provides a comprehensive view of the functional status of the complement system.
• Cons of Alternatives: May require multiple tests to get a complete picture.

Patient Experience

• The patient will experience a minor needle prick during the blood draw.
• Mild discomfort or bruising at the puncture site is possible.
• No significant pain or after-effects from the procedure.
• The patient can expect their doctor to discuss the results and implications during a follow-up appointment. Pain management is typically unnecessary for this procedure.