Alpha Defensin, Lateral Flow Assay, Synovial Fluid


Abbrev Code:ALDEF   
Order Code:LAB6665Order Name:Alpha Defensin LFA Synovial Fluid
Synonyms:Synovasure; Periprosthetic Joint Infection (PJI)
Methodology:Lateral Flow Assay (LFA)
CPT Codes: 83518 x1, 83518 x1
Turnaround Time:Specimens are sent to the reference laboratory daily; testing is performed Mon, Fri, Sun and results are reported within 1 day.
Special Instructions:This test should only be used for patients with total joint prothesis. If specimen is grossly hemolyzed, see Synovasure, Synovial Fluid ELISA (bloody or hemolyzed specimen that is inadequate for LFA assay) Lab Guide page.
Associated Links:

Synovasure Request Form, See Lab Guide page: Synovasure, Synovial Fluid - ELISA (bloody or hemolyzed specimen that is inadequate for LFA assay) [Lab Guide page 7003]



Collection Instructions

Specimen:Synovial Fluid
Optimal Volume:1 mL
Minimum\Peds Volume:0.1 mL
Container:Plastic leakproof container, sterile
Alternate Containers: Red (no gel)
Collection Instructions:Specimen source and type of joint are required. If not obtained from a prosthetic joint, testing will be cancelled.
Causes for Rejection:If not obtained from a prosthetic joint, testing will be cancelled. Grossly hemolyzed.


Processing and Shipping

Specimen Processing:Do not process. Transport specimen in the original collection container. Indicate specific collection site on collection container. Separate specimens must be submitted when multiple tests are ordered. Store in refrigerator.
Shipping Instructions:Ship at refrigerated temperature.
Stability:7 days refrigerated.
Test Performed at or Referral Lab Lab Sendouts  (Mayo Medical Laboratories)
Referral Lab number:ALDEF


Interpretive

Reference Range:
All ages Negative
Interpretation:
Negative No alpha defensin detected in synovial fluid, suggesting absence of prosthetic joint infection.
Positive Alpha defensin in synovial fluid detected suggesting presence of prosthetic joint infection. Additional microbiologic studies (e.g., culture, molecular detection) are recommended.
Limitations:
  • Presence of greater than 1 million/mcL red blood cells in the synovial fluid specimen may lead to false negative results. This represents dilution of the synovial fluid specimen with greater than 20% blood.
  • Alpha defensin testing should be used to evaluate for the presence of a prosthetic joint infection if other clinical and diagnostic test findings (i.e., synovial fluid cell count and differential) are inconclusive.
  • Test results should be utilized in conjunction with other clinical and diagnostic findings to aid the diagnosis of prosthetic joint infection (PJI).
  • This kit has been developed for use with freshly collected synovial fluid only. The use of this kit with any other specimen type may lead to inaccurate test results. The use of synovial fluid diluted with saline, blood, contrast agent, or any substances injected into the joint may lead to false-negative results.
  • The performance of this test has only been validated for conditions evaluated by the Musculoskeletal Infection Society (MSIS) criteria.
  • A decrease in sensitivity (an increased likelihood of false-negative results) has been observed in the presence of a sinus tract communicating with the prothesis.  Since the presence of a sinus tract is definitive evidence of PJI, use of this test under those circumstances is not recommended.
  • False-positive results have been reported in the presence of metallosis.
  • A negative test does not preclude the possibility of infection.
  • Synovial fluid obtained after repeated aspirations within a short time  period might lead to false-negative results due to lack of buildup of alpha defensin.
Use:Alpha defensin in synovial fluid detected, suggesting presence of prosthetic joint infection. Additional microbiologic studies (e.g., culture, molecular detection) are recommended.

Detection of alpha defensins 1-3, human host response proteins, in synovial fluid of adults with a total joint replacement who are being evaluated for revision surgery.

This test is not intended to be used to determine timing for reimplantation in 2-stage procedures.
 


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