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HelpTEST ID SLFA Cryptococcus Antigen Screen with Titer, Serum
Reporting Name
Cryptococcus Ag Screen w/Titer, SSpecimen Type
SerumSpecimen Required
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL Serum
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
Specimen Minimum Volume
Serum: 0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum | Refrigerated (preferred) | 14 days |
| Frozen | 14 days |
Testing Algorithm
If the screen result is positive, the Cryptococcus titer will be performed at an additional charge.
Method Name
Lateral Flow Assay (LFA)
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
Reference Values
Negative
Day(s) Performed
Monday through Sunday
Reflex Tests
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| SLFAT | Cryptococcus Ag Titer, LFA, S | Yes | No |
Report Available
Same day/1 to 2 daysSpecimen Retention Time
14 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
87899
Forms
If not ordering electronically, complete, print, and send Infectious Disease Serology Test Request (T916) with the specimen.
Useful For
Aiding in the diagnosis of cryptococcosis
This test should not be used as a test of cure or to guide treatment decisions.
This test should not be used as a screening procedure for the general populations.
Disease States
- Cryptococcosis
Clinical Information
Cryptococcosis is an invasive fungal infection caused by Cryptococcus neoformans or Cryptococcus gattii. C neoformans has been isolated from several environmental sources, especially weathered pigeon droppings. Historically, C gattii was associated with tropical and subtropical regions. More recently, it has been recognized as endemic in British Columbia and the Pacific Northwestern US and is associated with several different tree species.
Infection is usually acquired via the pulmonary route. Patients are often unaware of any exposure history. Approximately half of the patients with symptomatic disease have a predisposing immunosuppressive condition such as AIDS, steroid therapy, lymphoma, or sarcoidosis. Symptoms may include fever, headache, dizziness, ataxia, somnolence, and cough. While the majority of C neoformans infections occur in immunocompromised patient populations, C gattii is has a greater predilection for infection of healthy individuals.(1,2)
In addition to the lungs, cryptococcal infections often involve the central nervous system (CNS), especially in patients with HIV infection. Mortality among patients with CNS cryptococcosis may approach 25% despite antifungal therapy. Untreated CNS cryptococcosis is invariably fatal. Disseminated disease may involve any organ system and usually occurs in immunosuppressed individuals.
Cautions
A negative result does not preclude diagnosis of cryptococcosis, particularly if only a single specimen has been tested and the patient exhibits symptoms consistent with cryptococcosis.
A positive result is indicative of cryptococcosis; however, all test results should be reviewed considering other clinical findings
Testing should not be performed as a screening procedure for the general population and should only be performed when clinical evidence suggests the diagnosis of cryptococcal disease.
Testing hemolyzed serum specimens may lead to false-negative results due to the high background color on the lateral flow assay strip.
Although rare, extremely high concentrations of cryptococcal antigen can result in weak test lines and in extreme instances, yield negative test results.
This assay has not been evaluated for cross-reactivity in patients with trichosporonosis.
Method Description
The Cryptococcus antigen (CrAg) lateral flow assay is a sandwich immunochromatographic assay. Specimens and diluent are added to a test tube and the lateral flow device added. The test uses specimen wicking to capture gold-conjugated, anticryptococcal antigen monoclonal antibodies and gold-conjugated control antibodies deposited on the test membrane. If cryptococcal antigen is present in the specimen, it binds to the gold-conjugated, anticryptococcal antigen antibodies. This complex wicks up the membrane and interacts with the test line, which has immobilized anticryptococcal antigen monoclonal antibodies. The antigen-antibody complex forms a sandwich at the test line causing a visible line to form. A valid test shows a visible line at the control line. Positive test results create 2 lines (control and specimen) while negative results form only the control line.(Package insert: CrAg Lateral Flow Assay. IMMY; Rev 06/27/2019)