So many reports of FUO have also been published in China, but have been limited to single-facility or limited-region studies; no nationwide studies have yet been conducted. Moreover, few assessments of tests used in the diagnostic evaluation of FUO have been reported. In particular, few studies have assessed the clinical usefulness of tests such as serum procalcitonin or positron emission tomography (PET) in China, although these tests are now frequently used.