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Test Code LAB3170 HIV Antigen and Antibody

Clinical System Name

HIV Antigen and Antibody

Description

This testing detects HIV-1 p24 Antigen in addition to HIV-1 and HIV-2 antibodies. Positive and equivocal results require further testing. The added detection of HIV-1 p24Ag shortens the antibody-negative window period associated with acute HIV-1 infection. Reactive samples will reflex to additional immunoassay testing for confirmation.

Sample Requirements

Specimen: Whole Blood

Container(s): Lavender/EDTA

Preferred Vol: 4 mL

Minimum Vol: 2 mL

 

Note: Other acceptable sample types include: Gold SST, Red, Gold Microtainer, Dark Green/Sodium Heparin, Lt. Green/Lithium Heparin Microtainer, 

For possible reflex to PCR, specimens collected on patients <18 months cannot be shared with any other testing.  For other samples, please mark clearly on the label any add on samples.

Processing Instructions

Reject due to:

Spin: Y

Aliquot:Y

Temp: 2 - 8 C

Storage location: Spin blood, refrigerate plasma in a plastic tube affixed with a large computer label in the CPA refrigerator. Store in CPA fridge, FrigF rack

 

 

Off-site collection:

Stability

Specimen Type Temperature Time
plasma Room temp 48 h
  Refrigerated 7 d
  Frozen 2 m
whole blood Room temp 24 h*

 

*False positives may occur if the plasma remains with the cells for >24 hours.

Performing Laboratory

Seattle Children's Laboratory  

Department

Department:  Chemistry

Location: Chem East

Phone Number:  (206) 987-2617

 

 

Synonyms

AIDS Virus Antibody Test
HIV Screening
HIV Serology
HTLV III Antibody
HIV AgAb

Availability

STAT Performed TAT
N M - F 1-4 d

 

Please contact the Chemistry Department (987-2565 or 987-3694) if STAT testing is requested.  If Chemistry is unavailable (evenings), contact the clinical pathologist on call.

 

 

Methodology

Method: Immunoassay on Bioplex 2200

Analytical Volume: 0.5 mL plasma, additional volume needed for possible RNA testing on children <18 months

Limitations:

Reference Range

 

Negative

 

CPT Codes

87389

 

Clinical Information

In children <18 months, maternal antibodies may still be present which can cause a false positive HIV antibody/antigen result.  Orders on children <18 months, will be are reviewed by the Chemistry team to assess pre-test probability of mom and baby.  Recommended testing for higher pre-test probability is HIV RNA Quantitation.