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UW Health SMPH
American Family Children's Hospital

UW Hospital and Clinics Lab Test Directory

Test Name: Cryptococcal Ag


CPT Code(s): 86403

Methodology: Latex Agglutination

Clinical Significance: Establish the presence of Cryptococcus neoformans/gattii antigen.

Days Performed: Daily, dayshift.

Turnaround Time: Stat: Not available stat.
Routine: Up to 24 hours.

Specimen Requirements

Specimen: Blood

Collection Container: Preferred: Red top
Also Acceptable: Red cap with yellow ring (SST), Royal blue top

Collection Volume: Preferred: 3 mL
Pediatrics: 1 mL

Sample Analyzed: Serum

Volume Required: Preferred: 1 mL
Pediatrics: 0.5 mL

Specimen Transport: Transport specimen to UWHC Microbiology Laboratory (B4/231). Transport with coolant pack if coming from outreach location.

Stability: Refrigerated: 7 days
Frozen: Indefinitely


Expected Results:


Test Limitations:

False positives on serum samples may be seen in patients with rheumatoid arthritis. Occasionally, high levels of protein in the sample may interfere.

Critical Calls: View

Additional Information:

The test detects antigen of both C. neoformans and C. gattii.


Presence of cryptococcal polysaccharide is indicative of cryptococcosis.


Rheumatoid factor in serum or Trichosporon beigelii infection may cause a false positive reaction.


NOTE: 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 a health care provider. Positive tests should be confirmed by culture.


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




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