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Mayo Clinic Laboratories

Test Code HIVRFL HIV-1 p24 Antigen and Total Antibodies to HIV-1 and HIV-2 in Plasma (with Reflex)

Important Note

This test may be affected by biotin interference. Patients on high dose biotin (5mg/day or more) should not have samples drawn until at least 24 hours after the last biotin administration.

Infectious

Specimen and Container/Tube

Specimen Type: Plasma

Preferred Specimen: Lavendar Top (6 mL)

Specimen Stability

Storage Temperature

Stability

Room Temperature

7 days

Refrigerated

4 weeks

Frozen

3 months*

 

* Please refer to Microbiology/Immunology procedures for stability claims for HIVSD and Mayo's website for Viral Load testing requirements. Plasma must be separated from the red cells within 24 hours of collection.

 

Note: May be frozen up to 6 times.

Collection Instructions

Collect specimen per standard laboratory collection procedures. 

Specimen Handling and Transport Instructions

UCMC Onsite Instructions: 

Collect specimen per standard collection procedure and send to laboratory immediately. 

 

UCMC Offsite and UC MedLab Outreach Instructions: 

  • Samples should be centrifuged within 2 hours of collection.
  • Centrifuge specimens at >2500 x g for 10 minutes at room temperature.
  • Aliquot sample into plastic transport tube containing a minimum of 0.2 mL of specimen.
  • Samples must be sent room temperature at 15-25oC.

Rejection Criteria

  • Common specimen rejected situations include: incorrect specimen type, insufficient volume, missing or incomplete specimen identifiers, incorrect specimen transport, or specimens outside stability limits. 
  • Specimens that are clotted or grossly hemolyzed.
  • Specimens that were transported unspun/whole blood and draw time is greater than 6 hours

Reference Values

Test

Age

Sex

Interpretation

HIV Ag

All

All

Non-Reactive

HIV Ab

All

All

Non-Reactive

HIV DUO

All

All

Non-Reactive

Critical Values

Analyte

Unit

Low

High

Age

N/A

N/A

N/A

N/A

N/A

Turnaround Time

Turnaround times are relative to the time the specimen is received in the test laboratory. 

 

STAT Turnaround Time: 1 hour

Routine Turnaround Time: up to 4 hours

Testing Schedule:  24/7

Clinical Indications

AIDS is caused by 2 known types of HIV. HIV type 1 (HIV-1) is found in patients with AIDS or AIDS-related complex, and in asymptomatic infected individuals at high risk for AIDS. The virus is transmitted by sexual contact, by exposure to infected blood or blood products, or from an infected mother to her fetus or infant. HIV type 2 (HIV-2) infection is endemic only in West Africa and it has been identified in individuals who had sexual relations with individuals from that geographic region. HIV-2 is similar to HIV-1 in viral morphology, overall genomic structure, and its ability to cause AIDS.

 

Antibodies against HIV-1 and HIV-2 are usually not detectable until 6 to 12 weeks following exposure and are almost always detectable by 12 months. They may fall to undetectable levels (ie, seroreversion) in the terminal stage of AIDS when the patient’s immune system is severely depressed, but HIV p24 antigen should be detectable and yield reactive results with the HIV antigen-antibody combination detection assays.

Test Components

HIV Ag

HIV Ab

HIV DUO

Methodology

Electrochemiluminescence immunoassay (ECLIA) (Roche Diagnostics)

CPT Codes

87389

LOINC Codes

56888-1

Additional Information

Routine serologic screening of patients at risk for HIV-1 or HIV-2 infection usually begins with a HIV-1/-2 antigen and/or antibody screening test, which may be performed by various US Food and Drug Administration-approved assay methods, including rapid HIV antibody tests, enzyme immunoassays, and chemiluminescent immunoassays. In testing algorithms that begin with these methods, supplemental or confirmatory testing should be requested only for specimens that are repeatedly reactive by these methods.

Last Review Date

05/30/25

Volume

Preferred Volume: 0.5 mL

Minimum Volume: 0.2 mL