RBC Lysis Tests
RBC Lysis Tests
RBC lysis tests are specialized diagnostic procedures used to detect increased sensitivity of red blood cells to complement-mediated lysis, primarily in the diagnosis of Paroxysmal Nocturnal Hemoglobinuria (PNH).
Key Points:
- Primary diagnostic tools for PNH
- Assesses complement sensitivity
- Includes Ham test and Sucrose lysis test
- Qualitative and quantitative results
- Historical gold standard tests
Basic Principles:
- Complement activation pathways
- Membrane vulnerability assessment
- RBC sensitivity to lysis
- pH and osmotic variation effects
Ham Test (Acid Hemolysis Test)
Principle:
- Based on acidified serum lysis
- Tests complement-mediated hemolysis
- Measures RBC sensitivity to acidified conditions
- Named after Dr. Thomas Ham
Technical Details:
- Test Conditions
- pH maintained at 6.2-6.8
- Temperature: 37°C
- Incubation time: 1 hour
- Fresh normal serum required
- Quality Controls
- Normal RBC control
- Known PNH positive control
- Serum controls
Sucrose Lysis Test
Principle:
- Based on isotonic sucrose solution
- Tests complement activation
- Assesses membrane fragility
- Simpler than Ham test
Technical Specifications:
- Test Components
- Isotonic sucrose solution
- Patient RBCs
- Fresh normal serum
- Buffer solutions
- Test Conditions
- Room temperature incubation
- 30-minute observation
- Specific sucrose concentration
Test Methodology and Procedures
Ham Test Procedure:
- Sample Preparation
- Fresh patient blood collection
- RBC washing steps
- Serum acidification
- Control preparation
- Test Steps
- RBC suspension preparation
- Acidified serum addition
- Incubation process
- Hemolysis assessment
Sucrose Test Procedure:
- Sample Requirements
- Fresh blood sample
- Normal donor serum
- Sucrose solution preparation
- Execution Steps
- Solution mixing
- Incubation timing
- Visual assessment
- Spectrophotometric reading
Result Interpretation
Ham Test Results:
- Positive Result
- >5% hemolysis
- Visual color change
- Spectrophotometric confirmation
- Negative Result
- <3% hemolysis
- No significant color change
- Normal RBC stability
Sucrose Test Results:
- Positive Indicators
- Visual hemolysis
- Pink/red supernatant
- Quantitative measurement
- Result Validation
- Control comparison
- Repeatability check
- Clinical correlation
Clinical Applications and Correlation
Diagnostic Applications:
- Primary PNH Diagnosis
- Initial screening
- Confirmation testing
- Disease monitoring
- Other Conditions
- Congenital dyserythropoietic anemia
- Hereditary spherocytosis
- Autoimmune hemolytic anemia
Modern Context:
- Comparison with Flow Cytometry
- Sensitivity differences
- Specificity comparison
- Current role in diagnosis
- Clinical Guidelines
- Testing algorithms
- Result interpretation
- Follow-up recommendations
