HIV-1 Antigen & HIV-1/HIV-2 Antibody w/ Reflex to Western Blot

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Brief Description

Specimens will be screened by a CMIA test for the qualitative detection of HIV-1 p24 antigen, and IgM and IgG antibodies to HIV-1 and/or HIV-2. Any repeatedly reactive CMIA specimen will be confirmed with a Western Blot test that detects and identifies antibodies to Human Immunodeficiency Virus Type 1 (HIV-1). If the HIV-1 Western Blot is negative or indeterminate, the specimen may undergo more supplementary testing such as HIV nucleic acid testing if specimen requirements are met. This test is not intended for use in screening blood or plasma donors. This test has not been FDA approved for children less than 2 years of age or for cadaveric specimens.

Laboratory Unit



Chemiluminescent Microparticle Immunoassay (CMIA) / Western Blot

Specimen Collection

One 6 mL red top vacutainer tube or EDTA, heparin, serum separator (SST)


Serum, plasma
Store specimens at 2-8°C for 7 days.
After 7 days, the serum/plasma must be removed from clot, red blood cells, or separator gel and stored frozen at -20°C or colder
Specimens should be sent daily or next working day
Transport in SPHL shipping containers at room temperature or with coolant (if available)

Acceptable Specimen

Serum, plasma

Possible Results

CMIA:  Reactive, Non-Reactive, Unsatisfactory
Western Blot:  Positive, Negative, Indeterminate

Reference Range

HIV Ag/Ab Combo:  Non-Reactive
HIV-1 Western Blot:  Negative

Unacceptable Conditions

No Name on Specimen
Name on Specimen Does Not Match Name on Request Form
Quantity Not Sufficient
Grossly Hemolyzed

Interfering Substances

Hemolysis and bacterial contamination

Result Reported

1-3 days after receipt of specimen


For private entities, there is a $10 handling fee.

CPT Codes

87389 HIV-1 Ag/HIV-1 and HIV-2 Ab; if reflexed, add 86689 Western Blot


HIV Ag/Ab: 56888-1, Western Blot: 5221-7

Additional Information

Testing alone cannot be used to diagnose AIDS, which is a clinical syndrome. The diagnosis of AIDS must be established clinically. A nonreactive result does not exclude the possibility of exposure to or infection with HIV-1 and/or HIV-2. Nonreactive results may be because of antigen and antibody levels that are below the limit of detection of this assay.

Effective April 1, 2012, the HIV Blue Card, officially known as the Provider's Confidential Report of HIV/AIDs Infection report form (MO 580-1641), will no longer be provided with the positive HIV Western Blot laboratory results. Click here to view letter.