CPT® Code 87900

The CPT® Code 87900 refers to a laboratory test that predicts the drug susceptibility phenotype of infectious agents, specifically utilizing regularly updated genotypic bioinformatics. This test is particularly relevant in the context of viral infections, such as HIV, where understanding the drug resistance profile of the virus is crucial for effective treatment planning. The process involves phenotypic testing, which, while labor-intensive and technically challenging, is essential for measuring how susceptible a virus is to specific drugs. This is achieved by determining the concentration of a drug that can inhibit viral replication in vitro, providing valuable insights into the effectiveness of potential antiviral therapies. Genotypic bioinformatics plays a significant role in this predictive process by identifying viral mutations that are associated with known drug resistance, thereby enhancing the accuracy of susceptibility predictions. The test typically requires a blood sample, which is obtained through a separately reported venipuncture, and the serum or plasma is then analyzed using advanced techniques such as polymerase chain reaction (PCR) or sequencing. This test is particularly ordered for patients with new onset HIV infections to assess the drug resistance of the transmitted viral strain, aiding in the formulation of an appropriate treatment regimen. Additionally, it may be utilized for patients with established HIV infections who are experiencing suboptimal viral load suppression after starting treatment or who show signs of virologic failure, indicated by elevated plasma HIV RNA levels despite adequate dosing of their antiviral therapy.