HIV Antibodies
Last updated: Thursday, 25, October, 2007
| Item | Process |
|---|---|
| Specimen | 10 mL blood in plain tube. Informed consent must be obtained from the patient prior to ordering the test. |
| Method | Immunoassay for detection of both HIV-1 and HIV-2 antibodies. Specialised laboratories confirm positive immunoassay results by immunoblot methods. |
| Reference Interval | Positive is significant, if confirmed by immunoblotting. |
| Application | Diagnosis is of HIV infection. Screening of blood, tissue or organ donors. Following exposure, the seronegative "widow" period may be from 3 weeks to several months. Occasional subtypes of HIV may be undetectable by some EIA methods. |
| Interpretation | Positive indicates HIV infection and must be confirmed by immunoblot and by testing on a seperate sample. False positives are rare, and can be further assessed by immunoblot, tests for HIV antigen or, preferably, HIV-1 RNA and repeat HIV antibody testing; see HIV Antigen, HIV-1 RNA. In terminal disease, HIV antibodies may be negative. HIV-1 is common worlwide; HIV-2 is less common and is largely confined to Africa. Patients where there is a high clinical suspicion and are negative for HIV antibody should undergo P24 antigen testing or Proviral DNA assay. |
| Reference | Schleupner CJ. In Mandell GL et al eds. Principles and Practice of Infectious Diseases. 4th ed. Churchill Livingstone 1995. Gaines H et al. Lancet 1987; 1:1249-1253. |