What laboratory value would be indicative of the need for PCP prophylaxis in a patient with HIV?

The necessity for prophylaxis against Pneumocystis pneumonia (PCP) in patients with HIV is primarily guided by the CD4+ T-cell count, which is a critical marker of immune function in these patients. A CD4+ count of 200/mm³ is generally recognized as a threshold indicating the increased risk for opportunistic infections, including PCP.

PCP prophylaxis is recommended when the CD4+ count drops below 200/mm³, making the correct choice a CD4+ count at this level or lower. In this case, a CD4+ count of 150/mm³ clearly demonstrates that the patient is at a heightened risk for infections like PCP, thus indicating the need for prophylactic treatment.

This understanding helps healthcare providers assess and manage the opportunistic infection risk in patients living with HIV. Having a CD4+ count below this threshold signifies a compromised immune system and a greater likelihood of developing PCP, justifying the initiation of prophylaxis to prevent this potentially life-threatening infection.