Research tagged [internal-medicine]

Diagnostic Framework for Fever of Unknown Origin in Immunocompetent Adults: A Peer-Reviewed Clinical Consensus

Background: Fever of Unknown Origin (FUO) in immunocompetent adults represents a significant diagnostic challenge, often requiring extensive investigation despite initial comprehensive workup. The lack of specific localizing symptoms and the broad differential diagnosis necessitate a systematic, tiered approach to avoid diagnostic delays and inappropriate empirical treatments. This paper synthesizes expert clinical opinions on the subsequent diagnostic steps following an unrevealing initial evaluation. Methods: This consensus paper was developed from a clinical Q&A discussion on the tachyDx community platform, involving three verified physicians (an internist, an infectious disease specialist, and an oncologist) and garnering 60 community peer votes. The original clinical scenario involved a 42-year-old female presenting with four weeks of fever, weight loss, and night sweats, with an extensive negative initial workup. Expert responses were analyzed and synthesized to formulate a structured diagnostic pathway. Results: Key recommendations for second-tier investigations include 18F-FDG PET/CT, which demonstrates a diagnostic yield of approximately 50% and guides targeted biopsies. Specific laboratory markers such as ferritin (>1000 ng/mL for adult-onset Still's disease), LDH, uric acid, and beta-2 microglobulin (for occult lymphoma) were highlighted. The importance of repeat blood cultures for fastidious organisms and targeted biopsies (bone marrow, temporal artery, liver, or excisional lymph node) based on imaging findings was emphasized. Empiric anti-tuberculosis treatment in endemic areas and empiric steroid therapy for adult-onset Still's disease were recommended only under strict clinical and laboratory criteria. Conclusions: A systematic, tiered diagnostic approach incorporating advanced imaging, specific biomarkers, and targeted biopsies is crucial for resolving FUO after an initial negative workup. Careful consideration of regional epidemiology and strict adherence to diagnostic criteria are paramount before initiating empiric therapies, particularly in conditions like tuberculosis and adult-onset Still's disease.