The client has been on treatment for rheumatoid arthritis for 3 weeks. During the administration of etanercept (Enbrel), it is most important for the nurse to check:

The most critical aspect to monitor when a client is receiving etanercept, an immunosuppressive medication used for rheumatoid arthritis, is the white blood cell counts and platelet counts. Etanercept works by inhibiting the tumor necrosis factor (TNF), which plays a key role in inflammation and immune responses. This immunosuppressive action can lead to a decreased ability to fight infections and can affect bone marrow function.

For this reason, regular assessments of blood counts are essential to identify any potential hematologic side effects, such as leukopenia (low white blood cell count) or thrombocytopenia (low platelet count), which can increase the risk of infection and bleeding. Monitoring these parameters helps ensure the client's safety during treatment and allows for timely intervention if abnormalities are detected.

While monitoring for injection site reactions, fatigue, pain, or taste changes may be relevant, they do not carry the same level of potential harm as the complications arising from altered blood counts, making the assessment of white blood cells and platelets paramount in this case.