Before initiating antiviral therapy in an HIV-1 patient diagnosed by enzyme immunoassay and confirmed by Western blot, which laboratory test should be performed?

Before initiating antiviral therapy in a patient diagnosed with HIV-1, it is crucial to evaluate several key laboratory parameters to guide treatment and monitor disease progression. Each of the laboratory tests mentioned plays a significant role in the management of HIV.

Quantitative plasma virus concentration, or viral load testing, is important for assessing the level of viral replication in the patient's body. This measurement helps determine the baseline viral load before starting therapy and is essential for evaluating the effectiveness of the treatment in subsequent follow-up.

The quantitation of CD4 lymphocytes is also essential since CD4 cell counts are a critical indicator of immune system health in individuals with HIV. The baseline CD4 count can assist in deciding when to start antiretroviral therapy and helps monitor the progression of HIV infection.

Phenotype/genotype resistance testing provides crucial information about any existing drug resistance in the HIV virus. This resistance testing can help tailor therapy to ensure that the selected regimen will be effective based on the patient's specific type of HIV and its current resistance patterns.

Each of these tests offers valuable insights that contribute to a comprehensive understanding of the patient’s HIV status and needs. Initiating treatment without this foundational knowledge could lead to suboptimal therapy and worse patient outcomes; therefore, performing all of these tests is advisable