A nurse is caring for a client who has HIV. Which of the following laboratory values is the nurse's priority?

Choice A rationale A positive Western blot is a confirmatory diagnostic test for HIV infection, establishing the presence of antibodies. While important, it is not an acute parameter reflecting the current status of immune function or risk of opportunistic infection. Choice B rationale A platelet count of 150,000/mm is at the lower limit of the normal range (150,000 to 450,000/mm). This value does not indicate a critical clotting abnormality or an immediate life-threatening bleeding risk. Choice C rationale A white blood cell (WBC) count of 5,000/mm is within the normal range (4,500 to 11,000/mm). This value does not suggest an acute, uncontrolled infection or severe neutropenia requiring urgent intervention. Choice D rationale A CD4-T-cell count of 180 cells/mm is critically low, falling below the diagnostic threshold of 200 cells/mm for an AIDS diagnosis. This severe immunosuppression places the client at highest immediate risk for developing life-threatening opportunistic infections and malignancies.