A 40-year-old man comes to the office with concern of HIV infection. The patient had unprotected anal intercourse with a new partner during a business trip a month ago. A few days after the encounter, the patient learned that the partner was HIV positive. The patient immediately visited an urgent care clinic and was tested for HIV using a combination p24 antigen/HIV-antibody immunoassay. Although the test was negative and he has no symptoms, the patient feels anxious about the possibility of infection. He has no prior medical problems and takes no medication. The patient drinks alcohol on social occasions but does not use tobacco or illicit drugs. Temperature is 37.1 C (98.8 F), blood pressure is 130/70 mm Hg, and pulse is 80/min. No oropharyngeal erythema, exudate, or ulcers are present. Lung auscultation is unremarkable and heart sounds are normal. The abdomen is soft and nontender with no organomegaly. Bowel sounds are normal. No anal ulcers are present and genital examination is normal. Repeat testing for HIV antigen and antibody is positive. The patient's CD4+ count is 320/mm³ and serum HIV RNA (viral load) is 500,000 copies/mL. The risks and benefits of antiretroviral therapy are discussed, and the decision is made to initiate treatment. In addition to genotypic drug-resistance testing, what additional laboratory test should be obtained before initiating antiretroviral therapy?

Question

Quizplus · Accepted Answer

Explanation: Patients with newly diagnosed HIV infections require laboratory testing to stage the disease, determine appropriate antiretroviral therapy, and identify coinfections and comorbidities. This patient has received appropriate testing (CD4 count, viral load, HIV genotyping) for HIV staging and drug resistance. Prior to the initiation of antiretroviral therapy, testing for coinfection with hepatitis B virus is required as some antiretroviral medications have dual activity against both hepatitis B virus and HIV. These medications are often used preferentially in patients with both infections. Patients are also typically screened for tuberculosis, hepatitis C virus, and sexually transmitted pathogens (eg, Treponema pallidum, Neisseria gonorrhoeae). (Choice A) Beta-D-glucan is a fungal cell wall component that is often elevated in invasive fungal infections (eg, aspergillosis, candidiasis). This patient is asymptomatic, and beta-D-glucan is not part of routine laboratory testing. (Choice B) Patients with HIV are at increased risk of cytomegalovirus (CMV) reactivation with resultant viremia or end-organ disease (eg, retinitis). This patient is asymptomatic, routine CMV testing is not a part of initial HIV care, and most CMV reactivations occur at CD4 counts <100/mm³. (Choice C) Patients with HIV are at increased risk for cardiovascular disease and require screening for hypertension, hyperlipidemia, diabetes mellitus, and tobacco abuse. An echocardiogram is not a part of initial screening. (Choice E) The risk of thyroid disease is not typically increased in HIV, and routine thyroid function testing is not required. Educational objective: Patients newly diagnosed with HIV require laboratory testing to stage the disease, determine appropriate antiretroviral therapy, and identify coinfections and comorbidities. Prior to initiation of antiretroviral therapy, testing for hepatitis B virus is required as some treatment regimens can target both infections.

A 40-Year-Old Man Comes to the Office with Concern of HIV