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Test Code LAB3170 HIV Antigen and Antibody

Clinical System Name

HIV Antigen and Antibody

Synonyms

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

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.

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.

 

 

Performing Laboratory

Seattle Children's Laboratory  

Department

Department:  Chemistry

Location: Chem East

Phone Number:  (206) 987-2617

 

 

CPT Codes

87389

 

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

 

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.

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.