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Test ID ALDEF Alpha Defensin, Lateral Flow Assay, Synovial Fluid

Ordering Guidance

This test should only be used for patients with a total joint prosthesis.

Necessary Information

Specimen source and type of joint are required. If not obtained from a prosthetic joint, testing will be canceled.


If ordering electronically, answers must be provided for the order entry questions.


If not ordering electronically, specimen source and type of joint must be provided on the request form.

Specimen Required

Collection Container/Tube: Plain red-top tube

Submission Container/Tube: Plastic vial

Specimen Volume: 0.6 mL

Useful For

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.

Method Name

Lateral Flow Assay (LFA)

Reporting Name

Alpha Defensin, Synovial Fluid, LFA

Specimen Type

Synovial Fluid

Specimen Minimum Volume

0.10 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Synovial Fluid Refrigerated 7 days

Clinical Information

Diagnosis of prosthetic joint infections (PJI) may be challenging in certain clinical scenarios. Multiple societies have defined criteria for establishing the presence of a PJI, including results from laboratory tests, clinical findings, and tissue histopathology. The challenge, however, is that results of these tests are frequently not available at the time of or after surgery. As an alternative, determining the cell count and differential on synovial fluid are frequently used biomarkers for PJI, however there is a lack of consensus on the optimal thresholds to use for a PJI diagnosis. Additionally, cell count and differential results require clinician interpretation as laboratories do not report abnormal levels correlating with PJI.


Alpha defensins are antimicrobial peptides released by activated neutrophils in response to infection and served as part of the host-defense innate immune system with broad antimicrobial activity against gram-positive and gram-negative bacteria, mycobacteria, fungi, and viruses. The presence of alpha defensins in synovial fluid may therefore be used by clinicians as a marker of PJI.

Reference Values


Reference values apply to all ages.



No alpha defensin detected in synovial fluid, suggesting absence of prosthetic joint infection.



Alpha defensin in synovial fluid detected suggesting presence of prosthetic joint infection. Additional microbiologic studies (eg, culture, molecular detection) are recommended.

Clinical Reference

Bonanzinga T, Ferrari MC, Tanzi G, et al: The role of alpha defensin in prosthetic join infection (PJI) diagnosis: a literature review. EFFORT Open Rev. 2019 Jan 23;4(1):10-13

Day(s) Performed

Monday through Friday, Sunday

Report Available

Same day/1 day

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
ALDEF Alpha Defensin, Synovial Fluid, LFA 94718-4


Result ID Test Result Name Result LOINC Value
607711 Alpha Defensin, Synovial Fl, LFA 94718-4
JOINT Is this for a prosthetic joint? 86955-2
ADSRC Alpha Defensin Source 72923-6