Jun 28, 2017




Clinical Hub,Tools & Resources,UWHC Lab Test Directory,Microbiology

Cryptococcal Ag with Titration if Positive

Cryptococcal Ag with Titration if Positive (CRAG) Microbiology Lab Test

Name: Cryptococcal Ag with Titration if Positive

Test Name: Cryptococcal Ag with Titration if Positive

Health Link Test Code: CRAG

LIS Test Code: CRAG

CPT Code(s): 87899, 87899-59 titer (if appropriate)

Methodology: Lateral Flow Assay

Clinical Information:

Establish the presence of Cryptococcus neoformans/gattii antigen.

Days Performed: Daily, dayshift.

In-Lab Turnaround Time: 1 day.

Stat In-Lab Turnaround Time: Not available stat.

Specimen: Blood or cerebrospinal fluid (CSF)

Collection Container: Numbered specimen tube from sterile disposable lumbar puncture tray or red top

Also Acceptable: Red cap with yellow ring (SST), Sterile screw cap container

Collection Instructions:

Adult Collection Volumes:

Blood - 3 mL

CSF - 0.5 mL


Pedatric Collection Volumes:

Blood - 1 mL

CSF - 0.5 mL

Collection Volume: See collection instructions.

Pediatric Collection Volume: See collection instructions.

Stability Refridgerated:

72 hours

Stability Frozen:


Sample Analyzed: Serum and cerebrospinal fluid (CSF)

Testing Volume: 0.1 mL

Pediatric Testing Volume: 0.1 mL

Specimen Transport:

Transport specimen to the laboratory. Transport with coolant pack if coming from clinic location.



Interpretation Type: Expected Results

Test Limitations:

Testing hemolyzed serum samples could lead to false negative results due to high background.


Although rare, prozoning effect may cause extreme high concentrations of cryptococcal antigen to result in weak test lines, and in extreme cases, yield negative test results.


Critical Calls: yes

Additional Information:

Presence of cryptococcal polysaccharide is indicative of cryptococcosis.


Titers performed on all positive specimens.  Titers may not be available until 24 hours after initial test on first positives.


The first positive specimen per patient will be called to health care provider. Positive tests should be confirmed by culture.


First positive CSF specimens will automatically have a culture performed if not already ordered due to the importance of recovering the causative organism for identification.


Because of the half-life of cryptococcal antigen, retesting of positive patients should be done no more frequently than every 5 days.