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Pericardial-fluid complement: normal values
Insights
Normal pericardial fluid complement levels are established for accurate diagnosis. Storing samples at -70°C is crucial, as lower temperatures significantly reduce complement levels, impacting interpretation of immunologic diseases.
Area of Science:
- Immunology
- Rheumatology
- Clinical Chemistry
Background:
- Pericardial fluid complement levels in systemic lupus erythematosus and rheumatoid arthritis are difficult to interpret due to limited data in healthy individuals.
- Establishing normal complement concentrations is essential for accurate diagnosis and understanding of pericardial diseases.
Purpose of the Study:
- To determine normal ranges for pericardial fluid complement components (C3, C4, and total hemolytic complement) under standardized conditions.
- To assess the impact of sample storage temperature on complement levels.
Main Methods:
- Standardized collection, storage, and assay methods were employed.
- Pericardial fluid samples were analyzed for C3, C4, and total hemolytic complement (CH50).
- The effect of storage at -20°C versus -70°C on complement levels was evaluated.
Main Results:
- Normal ranges were established: C3 (35-127 mg/dl), C4 (6.3-23 mg/dl), and total hemolytic complement (1.9-9.1 CH50 units).
- Storage at -20°C caused a 50% reduction in complement values compared to optimal storage.
- Optimal storage at -70°C is recommended to preserve complement integrity.
Conclusions:
- Normal pericardial fluid complement levels are relatively low.
- Caution is advised when interpreting reduced complement levels in pericardial fluid, especially if storage conditions are suboptimal.
- Accurate reference ranges and proper sample handling are critical for diagnosing immunologic conditions affecting the pericardium.
Abstract:
Reports of low pericardial-fluid complement levels in systemic lupus erythematosus and rheumatoid arthritis have been difficult to interpret, as few data are available to describe complement concentrations in patients without pericardial disease. The authors therefore determined normal values under standardized conditions of collection, storage, and assay. The normal ranges for pericardial-fluid C3, C4, and total hemolytic complement were 35-127 mg/dl, 6.3-23 mg/dl, and 1.9-9.1 CH50 units, respectively. Storage at -20 C resulted in a 50% reduction in values. Hence, storage at -70 C is recommended. As the level of pericardial-fluid total hemolytic complement is normally low, caution is needed in interpreting its apparent reduction in various immunologic diseases.