Final answer:
In systemic lupus erythematosus (SLE), fever related to infection should be reported immediately due to the high risk of serious complications in immunocompromised patients.
Step-by-step explanation:
The registered nurse (RN) should instruct the client diagnosed with systemic lupus erythematosus (SLE) to report fever related to infection immediately. This is critical because people with SLE are immunocompromised and at higher risk of infections, which can escalate quickly and be potentially life-threatening. While other symptoms such as weight loss, anorexia, depressed mood, and breaks in tissue integrity are important and should be managed, fever may indicate an underlying infection that requires urgent medical intervention. SLE can affect multiple organ systems, and its complications can be serious, thus prompt reporting and management of symptoms like fever is vital.