What tests are ordered for HIV management?

Essential Laboratory Tests for HIV Management

The comprehensive management of HIV requires a series of specific laboratory tests to monitor disease status, assess organ function, and screen for coinfections and comorbidities. 1

HIV Disease Monitoring Tests

• HIV Serologic Testing: Patients without documentation of HIV serostatus or who were tested anonymously should have confirmatory HIV serologic testing performed upon initiation of care 1

• CD4 Cell Count with Percentage: This should be obtained upon initiation of care as it is the primary marker of immune function and disease progression 1

  • Some experts recommend obtaining two baseline measurements before making treatment decisions due to substantial variation in CD4 counts, especially during acute illness 1
  • CD8 cell count and CD4:CD8 ratio measurements are unnecessary as they are not used in clinical decision making 1

• Plasma HIV RNA Level (Viral Load): A quantitative HIV RNA level should be obtained upon initiation of care to assess prognosis, determine need for antiretroviral therapy, define baseline levels, and monitor response to therapy 1

• HIV Resistance Testing: All patients should undergo genotypic resistance testing upon initiation of care to assess for transmitted drug resistance, even if therapy is deferred 1

  • For patients on failing regimens, resistance testing is essential to guide modification of antiretroviral therapy 1
  • For patients failing integrase strand transfer inhibitor (INSTI)-based regimens, specific genotypic testing for INSTI resistance should be ordered 1

• Coreceptor Tropism Assay: This test should be performed if the use of a CCR5 antagonist is being considered 1

• HLA-B*5701 Testing: Required before initiating abacavir therapy to identify patients at high risk for hypersensitivity reactions 1

Safety Laboratory Tests

• Complete Blood Count with Differential: Essential to assess for anemia, leukopenia, and thrombocytopenia which are common in HIV-infected persons 1

• Chemistry Panel: Important to assess renal and hepatic function 1

  • Includes alanine aminotransferase, aspartate aminotransferase, bilirubin, albumin, alkaline phosphatase, electrolytes, blood urea nitrogen, and creatinine 1

• Fasting Glucose/HbA1c: Recommended to screen for glucose intolerance and diabetes, which have increased prevalence in HIV-infected populations 1

• Fasting Lipid Profile: Required due to increased cholesterol and triglyceride levels associated with HIV infection, antiretroviral drugs, and host factors 1

• Urinalysis and Calculated Creatinine Clearance: Especially important for black HIV-infected patients and those with advanced disease or comorbid conditions due to increased risk of nephropathy 1

  • Should also be performed prior to initiating potentially nephrotoxic drugs such as tenofovir or indinavir 1

• Glucose-6-phosphate Dehydrogenase (G6PD): Screening is recommended upon entry into care or before starting therapy with oxidant drugs in patients with predisposing racial or ethnic backgrounds 1

Coinfection and Comorbidity Screening Tests

• Tuberculosis Screening: HIV-infected patients without history of tuberculosis should be tested for Mycobacterium tuberculosis infection using either a tuberculin skin test (TST) or interferon-γ release assay (IGRA) 1

• Toxoplasma gondii Screening: All HIV-infected patients should be tested for prior exposure to T. gondii by measuring anti-Toxoplasma IgG 1

• Hepatitis Virus Screening: Patients should be screened for hepatitis B virus (HBV) infection by testing for hepatitis B surface antigen (HBsAg), hepatitis B surface antibody (HBsAb), and antibody to hepatitis B total core antigen (anti-HBc) 1

  • Hepatitis C virus (HCV) screening should be performed using HCV antibody testing, with HCV RNA testing for those with positive antibody results 1

• Syphilis Screening: All patients should be screened for syphilis upon initiation of care and periodically thereafter, depending on risk 1

• Cytology: Cervical Pap tests should be performed; anal Pap tests should be considered if indicated 1

• Chest Radiography: Recommended for patients with positive tuberculosis test results or underlying lung disease 1

Special Considerations

• When monitoring viral load, patients should ideally be followed using the same HIV load assay throughout their care to ensure consistency 1

• For patients on specific medications, additional testing may be required:

  • For darunavir/ritonavir treatment, genotypic and/or phenotypic testing is recommended prior to initiation of therapy in treatment-experienced patients 2
  • Liver function tests should be monitored before and during therapy with darunavir/ritonavir due to risk of drug-induced hepatitis 2

• In treatment-experienced patients, resistance testing is particularly important to guide selection of effective antiretroviral regimens 3