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Test Code FCRYST Body Fluid Crystals, LAB940


Polarizing Microscope

Performing Laboratory

St. Luke's Hospital Cedar Rapids

Specimen Requirements

Abnormal synovial fluid may clot spontaneously and therefore, a portion of all specimens should be anticoagulated with either EDTA or heparin.  Forward specimen promptly to the testing laboratory.  Crystal examination should be performed within one hour of receipt, if possible.  If not, the specimen should be stored, well sealed, at room temperature. 


Note: Indicate specimen source on specimen container and in computer.


Reference Values

Negative for crystals

Day(s) Test Set Up

Monday through Sunday

Test Classification and CPT Coding


Useful For

The identification of specific crystals is particularly important in differentiation of crystal-induced arthritis. The most commonly seen crystals are monosodium urate (uric acid), found in cases of gout, calcium pyrophosphate, associated with pseudo gout and cholesterol crystals (seen rarely in synovial fluid in persons who have had a rheumatoid arthritis condition for a long time). Crystals of apatite (the major mineral found in cartilage), and steroid crystals resulting from drug injections in the joint may be seen as well. Calcium oxalate crystals may be seen in renal dialysis patients.