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HIV Test
Aka: HIV Test, HIV Antibody, HIV Screening, HIV Labs
- Indications
- See HIV Screening Indications
- Labs: HIV Diagnosis (2014 U.S. protocol)
- Step 1: HIV-1/HIV-2 EIA Antibody Test with p24 Antigen testing (fourth generation)
- Negative
- No HIV-1 or HIV-2 Antibody or p24 Antigen
- p24 Antigen is detectable by HIV Testing as early as 2 weeks after infection
- High Negative Predictive Value
- Retest in 2-4 weeks if new HIV Exposure in prior 2 weeks
- Positive
- Go to Step 2 for discriminatory assay
- Step 2: HIV-1/HIV2 Discriminatory Assay (Multispot)
- Negative for HIV-1 and HIV-2
- Go to step 3 for confirmatory, NAAT testing
- If NAAT Test not available, then report as HIV Indeterminate
- HIV-1 Antibody positive (most common in U.S.)
- Obtain viral load
- Start Combination Antiretroviral Therapy
- HIV-2 Antibody positive (West Africa, nRTI resistance)
- Start Combination Antiretroviral Therapy
- Step 3: HIV-1 RNA Nucleic Acid Amplification Test (NAT or NAAT) for HIV RNA Viral Activity
- Negative NAAT
- Retest in 2-4 if new HIV Exposure in prior 2 week
- Positive NAAT
- Acute HIV Infection (although rare False Positive tests occur)
- Start Combination Antiretroviral Therapy
- Labs: Timing of HIV Test detection (from transmission)
- Days 10-12 (1-2 weeks)
- HIV 1 nucleic acid amplification test (NAAT) for HIV RNA Viral Activity positive
- Days 15-17 (2 weeks)
- HIV p24 Antigen positive
- Day 21 (3 weeks)
- HIV-1/HIV-2 EIA Test (fourth generation) positive
- Day 28 (4 weeks)
- HIV-1/HIV2 Discriminatory Assay (Multispot)
- Day >35 (5 weeks)
- Unigold OraQuick positive
- HIV Western Blot positive
- References
- Masciotra (2011) J Clin Virol 52(Suppl 1):S17-22 [PubMed]
- Labs: HIV Screening
- First line screening (recommended)
- Combined HIV-1/HIV-2 Antibody and p24 Antigen Immunoassay (fourth generation test)
- Other HIV rapid Screening Tests (office based, perform Multispot/NAAT testing if positive)
- Uni-Gold Recombigen
- Alere Determine
- Rapid finger-stick test detects p24 Antigen and detects and distinguishes HIV-1 and HIV-2 Antibody
- Approved in U.S. by FDA in 2013
- OraQuick (oral swab based)
- Available as In-Home HIV Test as of 2013
- Approved for age 17 years old and older
- Results in 20-40 minutes
- Test Sensitivity
- Approaches 99% when performed in clinic
- Drops to 92% (False Negative Rate: 1 in 12) when performed at home (due to user error)
- Test Specificity: 99.98% (False Positive Rate: 1 in 5000)
- Most accurate at 3 months after exposure
- Older tests (replaced)
- HIV ELISAAntibody Test (1st generation HIV Tests)
- Replaced with other Screening Tests above
- Positive 3-8 weeks from infection
- Were often negative initially in acute onset
- Labs: Other HIV Tests (confirmatory, discriminatory and activity tests)
- CD4 Cell Count
- Best marker of HIV-related Immunosuppression, infection duration and prognosis
- Varies from person to person, lab to lab, by time of day, and most significantly by acute comorbid illness
- HIV-1/HIV2 Discriminatory Assay (Multispot)
- Discriminates between HIV-1 and HIV-2
- HIV-1 RNA Nucleic Acid Amplification Test (NAT or NAAT) for HIV RNA Viral Activity (HIV Viral Load)
- Test Sensitivity: 100% sensitive
- Test Specificity: 97.4% Specific
- Positive at 11-12 days from infection
- Higher rate of False Positives
- Low counts (<10,000) are often False Positives
- Labs: p24 Antigen (direct detection)
- Positive at 14-15 days from infection (falls within 6-8 weeks)
- Used as part of screening protocol (see above)
- Consider for Acute Retroviral Syndrome diagnosis
- Test Sensitivity: 88.7% (high False Negative Rate)
- Test Specificity: 100%
- (2001) Ann Intern Med 134:25-29 [PubMed]
- Older tests
- HIV Western Blot Assay
- Use as confirmatory test for first generation HIV Tests
- Replaced with Multispot and NAAT testing following 4th generation combination HIV-1/HIV-2/p24 tests
- Efficacy: False-negative HIV Test causes (Consider repeat testing or HIV Viral Load testing)
- Acute seroconversion (<4 weeks of HIV Infection)
- Advanced AIDS (Antibody based tests)
- Autoimmune Condition
- Hemodialysis patients (Renal Failure)
- Multiple pregnancies
- Multiple transfusions
- Cystic Fibrosis
- Liver disease
- Intravenous Drug Abuse
- Immunization
- HIV Vaccination (experimental only)
- Recent other Immunization
- Labs: Related Sexually Transmitted Disease Testing
- Syphilis Serology (Rapid Plasma Reagin, VDRL)
- Hepatitis B Serology
- Hepatitis C Serology
- Gonorrhea Culture
- Chlamydia Antigen
- Labs: Disease Screening Related to Advanced HIV or AIDS
- Tuberculin Skin Test (PPD, Mantoux)
- Consider Quantiferon-TB instead
- Dose: 0.5 cc injected (contrast with standard 0.1 cc)
- Positive: >5 mm (contrast with standard 10 mm)
- CytomegalovirusSerology (CMV)
- Toxoplasmosis Titer
- Gynecologic examination with Pap Smear
- HIV associated with advanced Cervical Cancer
- References
- (1997) Med Lett Drugs Ther 39:81-3 [PubMed]
- Mylonakis (2000) Arch Intern Med 160:2386-8 [PubMed]
- Sherin (2014) Am Fam Physician 89(4): 265-72 [PubMed]