Alpha Defensin, Lateral Flow Assay, Synovial Fluid
Use
This test is utilized for the detection of alpha defensins 1-3, which are human host response proteins, in the synovial fluid of adults with a total joint replacement being evaluated for revision surgery. Alpha defensins are antimicrobial peptides released by activated neutrophils in response to infection, functioning as part of the host-defense innate immune system. Their presence in synovial fluid can be indicative of a prosthetic joint infection (PJI). The test assists clinicians in diagnosing PJI, although it is not intended to determine the timing for reimplantation in two-stage procedures.
Special Instructions
This test is specifically intended for patients with a total joint prosthesis. If the specimen is not sourced from a prosthetic joint, alternative testing is advised and this test should not be utilized. Important ordering questions include whether the joint is prosthetic and the specific source of the synovial fluid. Electronic or manual entry of specimen source and type of joint information is required.
Limitations
This test has been validated for use with freshly collected synovial fluid only. Utilizing the assay on other specimen types, diluted synovial fluid, or samples with specific contaminants like saline or blood, can lead to false results. The performance is specifically validated for conditions evaluated by Musculoskeletal Infection Society criteria, and sensitivity decreases in cases involving sinus tract communication with the prosthesis and may yield false-negatives. Presence of metallosis can lead to false-positive results; thus, the results should be interpreted in conjunction with other clinical data.
New York Approved
Methodology
Immunoassay (Lateral Flow)
Biomarkers
LOINC Codes
- 94718-4
- 94718-4
- 107578-7
- 72923-6
Result Turnaround Time
1 day
Related Documents
For more information, please review the documents below
Specimen
Body Fluid
Volume
0.6 mL
Minimum Volume
0.1 mL
Container
Plastic vial
Collection Instructions
Collect synovial fluid from a prosthetic joint into a red-top tube without preservatives or clot activators. Transfer to a plastic vial for submission.
Storage Instructions
Refrigerate the specimen for up to 7 days. Ambient temperature storage is also acceptable for the same duration.
Causes for Rejection
Gross hemolysis, specimens collected in tubes with preservatives or clot activators, or not obtained from a prosthetic joint will be rejected.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 7 days |
| Refrigerated | 7 days |