Synovial fluid ferritin in rheumatic diseases

Area of Science:

• Rheumatology
• Biochemistry
• Medical Diagnostics

Background:

• Ferritin, an iron-storage protein, is present in synovial fluid.
• Elevated ferritin levels have been observed in various inflammatory conditions.

Purpose of the Study:

• To analyze synovial fluid ferritin levels in patients with different rheumatic diseases.
• To determine the diagnostic utility of synovial fluid ferritin in differentiating rheumatic conditions.

Main Methods:

• Analysis of synovial fluid ferritin levels in 49 patients with rheumatic diseases.
• Comparison of ferritin levels across rheumatoid arthritis, other inflammatory arthritides, calcium pyrophosphate arthropathy, and osteoarthritis.
• Correlation analysis with cell counts and synovial fluid/serum ferritin ratios.

Main Results:

• Synovial fluid ferritin levels were significantly higher in inflammatory arthritis compared to osteoarthritis (p < 0.05).
• Geometric mean ferritin levels: Rheumatoid arthritis (528 µg/l), other inflammatory arthritides (339 µg/l), calcium pyrophosphate arthropathy (507 µg/l), osteoarthritis (167 µg/l).
• No significant correlation was found between synovial fluid ferritin and cell counts or synovial fluid/serum ferritin ratios.

Conclusions:

• Synovial fluid ferritin is elevated in inflammatory joint diseases but shows considerable overlap between diagnostic groups.
• Measuring synovial fluid ferritin is of limited value as a differential diagnostic test for rheumatic diseases due to wide value scatter.