Cryptococcal Antigen
Label Mnemonic: CRYAG
Epic Lab Code: LAB2233
Downtime Form: A-1a Clinical Microbiology Laboratory Requisition
BT 6004
Bacteriology/Virology Section
CSF, Serum
Collection Medium:
Red top tube 5 mL (Clot Activator)
1 mL; CSF or serum (red top)
Delivery Instructions:
Deliver to laboratory immediately after collection.
Testing Schedule:
24 hrs/day, 7 days a week, including holidays. Results are available within 2 hours.
Test Limitations:
The presence of cryptococcal antigen is indicative of cryptococcosis. Monitoring titers is not recommended as low-level titers may persist for a year or more in the absence of active infection [3,4].

Samples that are positive by the cryptococcal antigen assay will automatically reflex to a titer.

Cryptococcal antigen titers obtained with this method (IMMY lateral flow) are usually higher than those obtained with latex agglutination, which is the method that most prior research and guidelines have used as a gold standard [1,2,5]. Titers acquired by different methods are not always interchangeable but the titers reported for the lateral flow assay at the University of Iowa have been calibrated to the most commonly used historical method (Meridian Bioscience CALAS latex agglutination) and should be considered comparable.

Hemolyzed samples may interfere with the lateral flow assay, causing a false-negative result. Other potential interferences such as Trichosporon spp. have not been evaluated.

[1] J. R. Perfect, W. E. Dismukes, F. Dromer, D. L. Goldman, J. R. Graybill, R. J. Hamill, T. S. Harrison, R. A. Larsen, O. Lortholary, M.- H. Nguyen, P. G. Pappas, W. G. Powderly, N. Singh, J. D. Sobel, and T. C. Sorrell, "Clinical Practice Guidelines for the Management of Cryptococcal Disease: 2010 Update by the Infectious Diseases Society of America," Clin Infect Dis., vol. 50, no. 3, pp. 291–322, Feb. 2010.
[2] O. Lortholary, G. Poizat, V. Zeller, S. Neuville, A. Boibieux, M. Alvarez, P. Dellamonica, F. Botterel, F. Dromer, and G. Ch๊ne, "Long- term outcome of AIDS-associated cryptococcosis in the era of combination antiretroviral therapy:," AIDS, vol. 20, no. 17, pp. 2183– 2191, Nov. 2006.
[3] S. Antinori, A. Radice, L. Galimberti, C. Magni, M. Fasan, and C. Parravicini, "The Role of Cryptococcal Antigen Assay in Diagnosis and Monitoring of Cryptococcal Meningitis," J. Clin. Microbiol., vol. 43, no. 11, pp. 5828–5829, Nov. 2005.
[4] A. E. Brouwer, P. Teparrukkul, S. Pinpraphaporn, R. A. Larsen, W. Chierakul, S. Peacock, N. Day, N. J. White, and T. S. Harrison, "Baseline Correlation and Comparative Kinetics of Cerebrospinal Fluid Colony-Forming Unit Counts and Antigen Titers in Cryptococcal Meningitis," J Infect Dis., vol. 192, no. 4, pp. 681–684, Aug. 2005.
[5] T. Kabanda, M. J. Siedner, J. D. Klausner, C. Muzoora, and D. R. Boulware, "Point-of-Care Diagnosis and Prognostication of Cryptococcal Meningitis With the Cryptococcal Antigen Lateral Flow Assay on Cerebrospinal Fluid," Clin Infect Dis., vol. 58, no. 1, pp. 113–116, Jan. 2014.
Laterial Flow Assay
CPT Code:
See Additional Information:
Specimens Requiring Immediate Delivery