|Values are valid only on day of printing.|
Birefringent crystals are found in the synovial fluid of >90% of patients with acutely inflamed joints.
Monosodium urate crystals are seen in gouty fluids and calcium pyrophosphate crystals are seen in chondrocalcinosis. The urates are usually needle-shaped, and the calcium crystals are often rhomboidal. Cholesterol crystals may also be observed.
Providing a definitive diagnosis for joint disease
Positive identification of crystals provides a definitive diagnosis for joint disease.
Powdered anticoagulants such as oxalate are themselves crystalline; their use may cause confusion masking the presence of synovial fluid crystals definitive for the disease.
If present, crystals are identified.
Kjeldsberg C, Knight J: Body fluids: Laboratory examination of cerebrospinal, seminal, serous and synovial fluids. Third edition. Chicago, American Society of Clinical Pathologists, 1993 pp 272-283, 292-293