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Test ID: SFC Crystal Identification, Synovial Fluid

Reporting Name

Crystal ID, Synovial Fl

Useful For

Identifying the presence and type of crystals in synovial fluid

Clinical Information

Birefringent crystals are found in the synovial fluid of more than 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.


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

Report Available

1 day

Day(s) Performed

Monday through Sunday

Clinical Reference

Hussong JW, Kjeldsberg CR: Kjeldsberg's Body Fluid Analysis. First edition. ASCP Press 2015

Method Name

Compensated Polarized Light Microscopy


Includes cytospin prep.

Specimen Type

Body Fluid

Specimen Required


Preferred: Lavender top (EDTA)

Acceptable: Green top (heparin)

Specimen Volume: 2 mL

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Body Fluid Refrigerated (preferred)
  Ambient  24 hours

Reference Values

None seen

If present, crystals are identified.

Test Classification

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
SFC Crystal ID, Synovial Fl 5781-0


Result ID Test Result Name Result LOINC Value
SFCID Crystal ID, Synovial Fl 5781-0
REV28 Reviewed By: 18771-6
Mayo Clinic Laboratories | Endocrinology Catalog Additional Information: