Test Catalog

Interpretive Handbook

Test 8719 :
Crystal Identification, Synovial Fluid

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

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.

Useful For Suggests clinical disorders or settings where the test may be helpful

Providing a definitive diagnosis for joint disease

Interpretation Provides information to assist in interpretation of the test results

Positive identification of crystals provides a definitive diagnosis for joint disease.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Powdered anticoagulants such as oxalate are themselves crystalline; their use may cause confusion masking the presence of synovial fluid crystals definitive for the disease.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

None seen

If present, crystals are identified.

Clinical References Provides recommendations for further in-depth reading of a clinical nature

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

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