Test Id : LFACX
Cryptococcus Antigen with Reflex, Spinal Fluid
Useful For
Suggests clinical disorders or settings where the test may be helpful
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 performed as a screening procedure for the general population.
Profile Information
A profile is a group of laboratory tests that are ordered and performed together under a single Mayo Test ID. Profile information lists the test performed, inclusive of the test fee, when a profile is ordered and includes reporting names and individual availability.
| Test Id | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| CLFA | Cryptococcus Ag Screen w/Titer, CSF | Yes | Yes |
Reflex Tests
Lists tests that may or may not be performed, at an additional charge, depending on the result and interpretation of the initial tests.
| Test Id | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| CLFAT | Cryptococcus Ag Titer, LFA, CSF | Yes | No |
| FGENC | Fungal Culture, CSF | Yes, (Order FGEN) | No |
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
If result is positive, Cryptococcus antigen titer will be performed at an additional charge.
If Cryptococcus antigen titer is positive, then fungal culture will be performed at an additional charge.
Method Name
A short description of the method used to perform the test
Lateral Flow Assay (LFA)
NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.
Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test
Aliases
Lists additional common names for a test, as an aid in searching
Fungal Serology
Cryptococcal Antigen, CSF
Cryptococcus gattii
Cryptococcus neoformans
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
If result is positive, Cryptococcus antigen titer will be performed at an additional charge.
If Cryptococcus antigen titer is positive, then fungal culture will be performed at an additional charge.
Specimen Type
Describes the specimen type validated for testing
CSF
Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing
Container/Tube: Sterile vial
Specimen Volume: 1 mL
Collection Instructions: Submit specimen from collection vial 2 (preferred), 3, or 4.
Forms
If not ordering electronically, complete, print, and send Infectious Disease Serology Test Request (T916) with the specimen.
Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the testing laboratory. The minimum volume is sufficient for one attempt at testing.
0.5 mL
Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected
| Gross hemolysis | Reject |
Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| CSF | Refrigerated (preferred) | 14 days | |
| Frozen | 14 days |
Useful For
Suggests clinical disorders or settings where the test may be helpful
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 performed as a screening procedure for the general population.
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
If result is positive, Cryptococcus antigen titer will be performed at an additional charge.
If Cryptococcus antigen titer is positive, then fungal culture will be performed at an additional charge.
Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Cryptococcosis is an invasive fungal infection caused by Cryptococcus neoformans or Cryptococcus gattii. C neoformans has been isolated from several sites in nature, particularly weathered pigeon droppings. C gattii was previously only associated with tropical and subtropical regions. More recently, however, this organism has been found to be endemic in British Columbia and the Pacific Northwestern United States 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 has a higher predilection for infection of healthy individuals.(1,2)
In addition to the lungs, cryptococcal infections frequently involve the central nervous system (CNS), particularly in patients infected with HIV. Mortality among patients with CNS cryptococcosis may approach 25% despite antibiotic therapy. Untreated CNS cryptococcosis is invariably fatal. Disseminated disease may affect any organ system and usually occurs in immunosuppressed individuals.
Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
CRYPTOCOCCUS ANTIGEN SCREEN WITH TITER
Negative
CRYPTOCOCCUS ANTIGEN TITER, LFA
Negative
FUNGAL CULTURE
Negative
If positive, fungus will be identified.
Reference values apply to all ages.
Interpretation
Provides information to assist in interpretation of the test results
The presence of cryptococcal antigen in any body fluid (serum or cerebrospinal fluid [CSF]) is indicative of cryptococcosis. Specimens that are positive by the lateral flow assay (LFA) screen are automatically repeated by the same method utilizing dilutions to generate a titer value. CSF specimens submitted for initial diagnosis that test positive by LFA should also be submitted for routine fungal culture. Culture can aid in differentiating between the 2 common Cryptococcus species causing disease (Cryptococcus neoformans and Cryptococcus gattii) and can be used for antifungal susceptibility testing, if necessary. CSF specimens submitted to monitor antigen levels during treatment do not need to be cultured.
Disseminated infection is usually accompanied by a positive serum test.
Higher Cryptococcus antigen titers appear to correlate with more severe infections. Declining titers may indicate regression of infection. However, monitoring titers to cryptococcal antigen should not be used as a test of cure or to guide treatment decisions, as low-level titers may persist for extended periods of time following appropriate therapy and the resolution of infection.
Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
A traumatic lumbar puncture and contamination of the cerebrospinal fluid (CSF) specimen with plasma may lead to a positive Cryptococcus antigen result from CSF in patients without neuroinvasive cryptococcosis.
A negative result does not preclude diagnosis of cryptococcosis, particularly if only a single specimen has been tested and the patient shows 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 populations and should only be performed when clinical evidence suggests the diagnosis of cryptococcal disease.
Although rare, extremely high concentrations of cryptococcal antigen can result in weak test lines and, in extreme instances, yield false-negative test results.
This assay has not been evaluated for cross-reactivity in patients with trichosporonosis.
Supportive Data
Cerebrospinal fluid (CSF) retrospective specimens (111) were tested in a blinded fashion by the IMMY Cryptococcus Antigen Lateral Flow Assay (LFA) and the Meridian Latex Agglutination (Meridian Bioscience Inc) assay within a 24-hour period. Of these 111 specimens, 45 were also tested by the Meridian Cryptococcus Antigen EIA also within a 24-hour period. Samples with discordant results after initial testing were repeated by both assays during the same freeze/thaw cycle. The results are summarized below in Table 1 and Table 2:
Table 1. Comparison of the IMMY LFA to the Meridian latex agglutination assay in CSF
| Meridian latex agglutination | ||||
| LFA IMMY | | Positive | Negative | Total |
| Positive | 18 | 0 | 18 | |
| Negative | 0 | 93 | 93 | |
| Total | 18 | 93 | 111 | |
Sensitivity: 100% (18/18); 95% CI: 81.2%-100%
Specificity: 100% (93/93); 95% CI: 96.0%-100%
Overall Percent Agreement: 100% (111/111); 95% CI: 99.0%-100%
Table 2. Comparison of the IMMY LFA to the Meridian Cryptococcus antigen EIA in CSF
| | Meridian EIA | |||
| LFA IMMY | | Positive | Negative | Total |
| Positive | 12 | 0 | 12 | |
| Negative | 0 | 33 | 33 | |
| Total | 12 | 33 | 45 | |
Sensitivity: 100% (12/12); 95% CI: 72.2%-100%
Specificity: 100% (33/33); 95% CI: 87.8%-100%
Clinical Reference
Recommendations for in-depth reading of a clinical nature
1. Speed B, Dunt D: Clinical and host differences between infections with the two varieties of Cryptococcus neoformans. Clin Infect Dis. 1995;21(1):28-34
2. Chen S, Sorrell T, Nimmo G, et al: Epidemiology and host- and variety-dependent characteristics of infection due to Cryptococcus neoformans in Australia and New Zealand. Australasian Cryptococcal Study Group. Clin Infect Dis. 2000 Aug;31(2):499-505. doi: 10.1086/313992
3. Perfect JR: Cryptococcosis (Cryptococcus neoformans and Cryptococcus gattii). In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 9th ed. Elsevier; 2020:3146-3161
4. Chang CC, Harrison TS, Bicanic TA, et al. Global guideline for the diagnosis and management of cryptococcosis: an initiative of the ECMM and ISHAM in cooperation with the ASM [published correction appears in Lancet Infect Dis. 2024;24(8):e485
5. Perfect JR, Bicanic T. Cryptococcosis diagnosis and treatment: What do we know now. Fungal Genet Biol. 2015;78:49-54. doi:10.1016/j.fgb.2014.10.003
Method Description
Describes how the test is performed and provides a method-specific reference
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, 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)
PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information
Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.
Monday through Sunday
Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.
Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location
Indicates the location of the laboratory that performs the test
Fees :
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.
- Authorized users can sign in to Test Prices for detailed fee information.
- Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
- Prospective clients should contact their account representative. For assistance, contact Customer Service.
Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.
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
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
CPT codes are provided by the performing laboratory.
CPT codes are provided by the performing laboratory.
87899-Cryptococcus Ag Screen w/Titer, CSF
87899-Cryptococcus Ag Titer, LFA, CSF (as appropriate)
87102-Fungal Culture, CSF (as appropriate)
LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.
| Test Id | Test Order Name | Order LOINC Value |
|---|---|---|
| LFACX | Cryptococcus Ag w/Reflex, LFA, CSF | 29896-8 |
| Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
|---|---|---|
| 62074 | Cryptococcus Ag Screen w/Titer, CSF | 29896-8 |