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Test Code ULFA Cryptococcus Antigen Screen, Lateral Flow Assay, Random, Urine


Specimen Required


Supplies: Urine Tubes, 10 mL (T068)

Submission Container/Tube: Plastic, 10-mL urine tube

Specimen Volume: 1 mL

Collection Instructions:

1. Collect a random urine specimen.

2. No preservative.


Secondary ID

604095

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.

 

This test should not be used as a screening procedure for the general population.

Highlights

Detection of Cryptococcus antigen in urine may be used as an adjunct method for diagnosis of disseminated infection with Cryptococcus neoformans/gattii, alongside culture and other serologic methods (eg, Cryptococcus antigen testing on serum or cerebrospinal fluid).

 

A negative result should not be used to rule-out infection.

Disease States

  • Cryptococcosis

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
ULFAT Cryptococcus Ag Titer, LFA, U No No

Testing Algorithm

If this screen is positive, the antigen titer will be performed at an additional charge.

Method Name

Lateral Flow Assay (LFA)

Reporting Name

Cryptococcus Ag Screen, LFA, U

Specimen Type

Urine

Specimen 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

Negative

Reference values apply to all ages.

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.

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

Performing 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

87899 (if appropriate)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
ULFA Cryptococcus Ag Screen, LFA, U 16693-4

 

Result ID Test Result Name Result LOINC Value
604095 Cryptococcus Ag Screen, LFA, U 16693-4

Forms

If not ordering electronically, complete, print, and send Infectious Disease Serology Test Request (T916) with the specimen.