A. History: Subacute (1-3 weeks7-14 days)
Differential Diagnosis
Infections: Tuberculosis, Infective endocarditis, Abscesses (e.g., intra-abdominal, dental), Typhoid fever
Autoimmune diseases: Still’s disease, temporal arteritis
Malignancies: lymphomas
Drug fever: from new medications started days to weeks earlier
| Next Pivotal Assessment | Findings |
|---|---|
This is often classified as Fever of Unknown Origin (FUO) if no cause is found after an initial workup.
Infectious: tuberculosis, occult abscesses, HIV, endocarditis
Inflammatory/autoimmune: lupus, vasculitis, rheumatoid arthritis
Neoplastic: lymphoma, renal cell carcinoma
Miscellaneous: drug fever, factitious fever (self-induced), deep vein thrombosis, thyroiditis
Clues: Often requires advanced workup, including imaging and sometimes biopsy
| Duration | Likely Causes |
|---|---|
| < 7 days | Viral or bacterial infections, acute inflammation |
| 1–3 weeks | TB, abscess, endocarditis, autoimmune diseases |
| > 3 weeks | FUO: infection, malignancy, autoimmune, other rare |
Let me know if you’d like to explore how to use fever pattern (intermittent, remittent, etc.) to aid diagnosis too.