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Updated: Jul 26, 2025
Synovial Fluid Analysis to Identify Osteoarthritis
Published on: October 20, 2022
Synovial fluid crystal analysis with compensated polarization using a gout analyser in clinical practice
Takayasu Kise1, Naoto Yokogawa1, Yuji Miyoshi1
1Department of Rheumatic Diseases, Tokyo Metropolitan Tama Medical Center, Tokyo, Japan.
Objective:
To validate the gout analyzer as a clinical method of synovial fluid crystal analysis.
Methods:
Thirty knee synovial fluid samples with suspected calcium pyrophosphate (CPP) crystals were analyzed. Within 48 hours after collection, each non-centrifuged sample was examined blindly and independently by one or more rheumatologists in the following order: 1) with an optical microscope under ordinary light, 2) with the same microscope under compensated polarization provided by a gout analyzer, and 3) with a fully equipped compensated polarized microscope with a rotating stage as the gold standard. As a reference, laboratory technicians analyzed fresh, centrifuged synovial fluid using a gout analyzer.
Results:
Of the 30 samples analyzed, CPP and monosodium urate (MSU) crystals were detected in 11 and four, non-centrifuged samples, respectively, using a fully equipped compensated polarized microscope. The rheumatologists' detection rate of crystals in the non-centrifuged synovial fluid under ordinary light and with a gout analyzer was 73.3% and 80%, respectively. The laboratory technicians' detection rate in fresh centrifuged synovial fluid using a gout analyzer was 100%.
Conclusion:
A gout analyzer may be used to diagnose gout and calcium pyrophosphate deposition disease definitively if a fully equipped compensated polarized microscope is unavailable.
