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HelpMayo Test ID ULFAT Cryptococcus Antigen Titer, Lateral Flow Assay, Urine
Specimen Required
Only orderable as a reflex. For more information see ULFA / Cryptococcus Antigen Screen, Lateral Flow Assay, Random, Urine.
Useful For
Aiding in the diagnosis of infection with Cryptococcus neoformans or Cryptococcus gattii
This test should not be used as a test of cure.
Method Name
Only orderable as a reflex. For more information see ULFA / Cryptococcus Antigen Screen, Lateral Flow Assay, Random, Urine.
Lateral Flow Assay (LFA)
Reporting Name
Cryptococcus Ag Titer, LFA, USpecimen Type
UrineSpecimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Urine | Refrigerated (preferred) | 14 days | |
| Frozen | 14 days |
Reject Due To
| Gross hemolysis | Reject |
| Turbid; Colored | Reject |
Clinical Information
Cryptococcosis is an invasive fungal infection caused by Cryptococcus neoformans or Cryptococcus gattii. The organism has been isolated from several sites in nature, particularly weathered pigeon droppings.
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 has a predilection for infection of healthy individuals.
In addition to the lungs, cryptococcal infections frequently involve the central nervous system (CNS), particularly in HIV-infected patients. Mortality associated with CNS cryptococcosis approaches 25% despite antifungal therapy, while untreated CNS cryptococcosis is invariably fatal. Disseminated disease may affect any organ system and usually occurs in immunosuppressed individuals.
Reference Values
Only orderable as a reflex. For more information see ULFA / Cryptococcus Antigen Screen, Lateral Flow Assay, Random, Urine.
Interpretation
The presence of cryptococcal antigen (CrAg) in any body fluid is strongly suggestive of infection with Cryptococcus neoformans or Cryptococcus gattii.
Declining titer results are suggestive of clinical response to therapy. However, monitoring CrAg titers should not be used as a test of cure, as low-level titers may persist for extended periods of time following appropriate therapy and disease resolution.
In addition to testing for CrAg, patients with presumed disease due to C neoformans or C gattii should have appropriate clinical specimens (eg, blood, bronchoalveolar lavage fluid) submitted for routine smear and fungal culture.
Cautions
A negative result does not preclude the diagnosis of cryptococcosis, particularly if only a single specimen has been tested and the patient shows symptoms consistent with cryptococcal infection.
A positive result is suggestive of cryptococcosis; however, all test results should be interpreted in light of other clinical findings.
Although rare, extremely high concentrations of cryptococcal antigen (CrAg) can result in weak-positive or false-negative results.
Patients with trichosporonosis or Capnocytophaga species infection may yield false-positive results.
If followed for clinical purposes, CrAg titers should be followed using the same assay.
Clinical Reference
1. Hazen KC, Howell SA: Candida, Cryptococcus, and other yeasts of medical importance. In: Murray PR, ed. Manual of Clinical Microbiology. 9th ed. ASM Press; 2007:1762-1788
2. Bruner KT, Franco-Paredes C, Henao-Martinez A, et al: Cryptococcus gattii complex infections in HIV-infected patients, Southeastern United States. EID. 2018 Nov; 24(11):1998-2002. doi: 10.3201/eid2411.180787
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 is added. The test uses specimen wicking to capture gold-conjugated anti-cryptococcal 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 anti-cryptococcal antigen antibodies. This complex wicks up the membrane and interacts with the test line, which has immobilized anti-cryptococcal 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)
Day(s) Performed
Monday through Friday
Report Available
1 to 4 daysSpecimen Retention Time
7 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
87899
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| ULFAT | Cryptococcus Ag Titer, LFA, U | 93766-4 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 604369 | Cryptococcus Ag Titer, LFA, U | 93766-4 |