University of Wisconsin–Madison Medical College of Wisconsin

Interpretation of HIV Serologies in the Era of PrEP: Two Cases of False Positives

Justin Temple, MD; Rob Striker, MD, PhD; Amy Pease, APNP

WMJ. 2025;124(2):176-179

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ABSTRACT

Introduction: More availability of HIV pre-exposure prophylaxis (PrEP) is needed to end the HIV epidemic, but this means more clinicians will encounter false positive HIV test results. These cases highlight such occurrences and the steps a clinician may take to determine the significance of such results.

Case Presentations: We present the case of a 68-year-old male who presented for routine follow-up for HIV PrEP and a 41-year-old transgender male who presented to establish care with a primary care clinician. On labs, both had repeatedly positive HIV antigen/antibody tests with undetectable viral loads.

Discussion: With increasing prescription of HIV PrEP comes a need for accurate interpretation of HIV serologies. HIV PrEP users may have altered stages of seroconversion. Additionally, heterophile antibody interference can lead to false positive or negative results.

Conclusions: The reader should gain an understanding of HIV testing, potential pitfalls, and next steps amidst unclear results.


Author Affiliations: Department of Family Medicine and Community Health, University of Wisconsin School of Medicine and Public Health (UWSMPH), Madison, Wisconsin (Temple); Department of Medicine, UWSMPH, Madison, Wisconsin (Striker); Vivent Health, Madison, Wisconsin (Pease).
Corresponding Author: Justin Temple, MD, Sixteenth Street Community Health Centers, 1032 S César E. Chávez Dr, Milwaukee, WI 53204; email justin.temple@sschc.org; ORCID ID 0009-0009-7111-3380
Financial Disclosures: None declared.
Funding/Support: None declared.
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