Fig. 2

Algorithmic approach to an ‘inappropriately well’ adult with the complaint of persistent fever. Abbreviations: DF, drug-induced fever; FF, factitious fever; FH, functional hyperthermia; HH, habitual hyperthermia; WAW, watch-and-wait. Notes: a Thermometer placement, circadian variation, luteal phase, physical activity, chewing, smoking, caffeine, sleep patterns. b Fever is usually hectic, and biological signs are inconsistent. Only a resolution of symptoms within 72 h after discontinuation of treatment, makes the diagnosis probable [72]. c Other clues: health care personnel, peregrination, undocumented fever, hyperpyrexia, psychiatric comorbidities, and inadequate urinary temperature [73, 74]. d The entire debate concerns the value given to lab tests and particularly to inflammatory biomarkers, whose performance is poor in nonhospital-based medicine. Serum protein electrophoresis seems to be more useful for detecting an inflammatory pattern