Laboratory Testing for Initial Assessment and Monitoring While on Antiretroviral Therapy
(Last updated:2/12/2013; last reviewed:2/12/2013)
A number of laboratory tests are important for initial evaluation of HIV-infected patients upon entry into care, during follow-up (if antiretroviral therapy (ART) has not been initiated), and before and after the initiation or modification of therapy to assess virologic and immunologic efficacy of ART and to monitor for laboratory abnormalities that may be associated with antiretroviral (ARV) drugs. Table 3 outlines the Panel’s recommendations for the frequency of testing. As noted in the table, some tests may be repeated more frequently if clinically indicated.
Two surrogate markers are routinely used to assess the immune function and level of HIV viremia: CD4 T-cell count (CD4 count) and plasma HIV RNA (viral load). Resistance testing should be used to guide selection of an ARV regimen; a viral tropism assay should be performed before initiation of a CCR5 antagonist; and HLA-B*5701 testing should be performed before initiation of abacavir (ABC). The rationale for and utility of these laboratory tests are discussed below.