Examkin

Soru

Zorluk: Çok zorOrdering Laboratory Tests

A 29-year-old man presents to an outpatient clinic with a 5-day history of fever, severe pharyngitis, profound fatigue, and a nonpruritic maculopapular rash on his trunk and extremities. He has no significant past medical history. Social history is notable for unprotected receptive anal intercourse with a new male partner 16 days ago. His temperature is 38.3°C (100.9°F), blood pressure is 118/76 mmHg, pulse is 102/min, and respirations are 16/min. Physical examination reveals generalized cervical and axillary lymphadenopathy. The physician suspects acute retroviral syndrome and initiates the standard diagnostic algorithm and pre-treatment evaluation.

Arrange the following laboratory tests in the most appropriate chronological sequence for establishing the definitive diagnosis, evaluating the baseline disease state, and preparing for the initiation of antiretroviral therapy.

  1. 1Fourth-generation HIV-1/2 antigen/antibody combination immunoassay
  2. 2HIV-1/HIV-2 antibody differentiation immunoassay
  3. 3HIV-1 nucleic acid amplification test (NAT)
  4. 4CD4+ T-lymphocyte count and quantitative HIV-1 RNA viral load
  5. 5Genotypic antiretroviral drug resistance testing and HLA-B*5701 allele screening

Cevap

The correct sequence begins with the 4th-generation combination immunoassay, followed by the antibody differentiation immunoassay, then the HIV-1 NAT to resolve indeterminate acute results, followed by baseline staging with CD4/viral load, and finally pre-treatment resistance and pharmacogenomic screening.
The evaluation of suspected acute HIV infection follows a strict diagnostic algorithm established by the Centers for Disease Control and Prevention (CDC), followed by a standardized pre-treatment baseline assessment. The process begins with the highly sensitive fourth-generation HIV-1/2 antigen/antibody combination immunoassay. If reactive, this must be followed by an HIV-1/HIV-2 antibody differentiation immunoassay. In acute HIV infection, the differentiation assay is typically negative or indeterminate because the p24 antigen (detected by the first test) appears before fully mature antibodies (detected by the second test). To resolve this discordance and confirm acute infection, an HIV-1 nucleic acid amplification test (NAT) is required. Once the diagnosis is definitively established, the physician must order baseline staging laboratories, primarily a CD4+ T-lymphocyte count and a quantitative HIV-1 RNA viral load. Finally, prior to or concurrent with initiating antiretroviral therapy, genotypic resistance testing and HLA-B*5701 allele screening must be performed to ensure the selected regimen is both effective and safely tailored to the patient.

Adım Adım Çözüm

1
Perform initial screening for HIV infection.
Fourth-generation HIV-1/2 antigen/antibody combination immunoassay.
This is the most sensitive initial screening test, capable of detecting both HIV antibodies and the p24 antigen, which appears earlier in the course of acute infection.
2
Confirm a positive initial screening test and differentiate the viral type.
HIV-1/HIV-2 antibody differentiation immunoassay.
Required to distinguish between HIV-1 and HIV-2 infections and to confirm the presence of antibodies. In acute HIV, this test is often negative or indeterminate because mature antibodies have not yet fully developed.
3
Resolve indeterminate or negative differentiation assay results in the setting of suspected acute infection.
HIV-1 nucleic acid amplification test (NAT).
Directly detects viral RNA. A positive NAT following a positive 4th-generation screen and a negative/indeterminate differentiation assay definitively diagnoses acute HIV-1 infection.
4
Establish baseline disease stage and immunological status after confirming the diagnosis.
CD4+ T-lymphocyte count and quantitative HIV-1 RNA viral load.
Essential for assessing baseline immune function and the magnitude of viremia, which guides clinical monitoring and establishes a reference point to assess future virologic suppression on therapy.
5
Optimize the initial antiretroviral therapy (ART) regimen for safety and efficacy.
Genotypic antiretroviral drug resistance testing and HLA-B*5701 allele screening.
Identifies transmitted drug resistance mutations and screens for potential abacavir hypersensitivity, ensuring the selected standard ART regimen is both effective and safe for the specific patient.

Anahtar Kavram

Standard HIV diagnostic testing algorithm and subsequent baseline pre-treatment evaluation sequence.
Bu soruyu puanla

Konular

Ordering Laboratory Tests

Bu konudan daha fazla soru