SHORT REPORT Potential use of procalcitonin concentrations as a diagnostic marker of the PFAPA syndrome Takao Yoshihara & Toshihiko Imamura & Kentaro Yokoi & Mayumi Shibata & Gen Kano & Shinya Osone & Kanae Yagi & Shinjiro Todo & Yumi Murakami & Yuichi Yamada & Hiroyuki Yamada & Shinji Satomura & Hiroyuki Ishida Received: 21 June 2006 / Accepted: 27 July 2006 / Published online: 30 September 2006 # Springer-Verlag 2006 Keywords PFAPA syndrome . Periodic fever . Procalcitonin PFAPA syndrome is a clinical entity of unknown etiology characterized by periodic episodes of high fever accompa- nied by aphthous stomatitis, pharyngitis/tonsillitis, and cervical adenitis [3, 5]. Since specific laboratory abnormal- ities for the PFAPA syndrome are inexistent, it is usually diagnosed clinically after excluding other probable causes of the fever, such as infection [1]. In PFAPA patients, discriminating between a fever attack due to bacterial infection and a fever attack due to noninfectious inflamma- tion constitutes a major difficulty. Because procalcitonin, a propeptide of calcitonin, is reported to be a sensitive marker of systemic bacterial infection [2, 4], we followed periph- eral leukocyte counts, CRP values and procalcitonin concentrations during the fever attacks associated with PFAPA syndrome in the hope of defining reliable criteria for its diagnosis. We determined serum procalcitonin concentrations in six PFAPA syndrome patients (two males and four females) with a median age of 7.5 (range 3–10) years and in 32 controls (bacterial, n=10 and non-bacterial, n=22). Sampling was performed on the third to fifth day of fever. In the PFAPA syndrome patients, febrile episodes started at the median age of 2.5 (range 1–7) years with each episode lasting 5–7 days and recurring every 3–4 weeks. The ethical committees of our institutes approved the study protocol and the guardians of all the patients gave their informed consent. Serum procalcitonin concentrations were measured by using the fully automated enzyme immunolu- minescent assay (Wako Pure Chemical Industries, Ltd.), which employs katacalcin monoclonal antibody and calci- tonin polyclonal antibody labeled with peroxidase for SphereLight 180 (Olympus Corporation). The detection limit was 0.1 ng/ml and the normal reference was set at <0.5 ng/ml. In PFAPA patients, the correlations between procalcitonin, CRP values and leukocyte counts were examined over 13 febrile episodes. Serum procalcitonin values ranged from 0.20 to 11.36 (median value 1.05) ng/ml in positive control subjects (Table 1), while all the negative controls had undetectable levels. During febrile episodes in PFAPA patients, which were confirmed not to be due to adenoviral or group A streptococcal infections, leukocyte counts and serum con- centrations of CRP were invariably and significantly Eur J Pediatr (2007) 166:621–622 DOI 10.1007/s00431-006-0281-2 T. Yoshihara (*) : T. Imamura : K. Yokoi : H. Ishida Department of Pediatrics, Matsushita Memorial Hospital, 5-55, Sotojima-cho, Moriguchi, Osaka 570-8540, Japan e-mail: yoshihara.takao@jp.panasonic.com M. Shibata : G. Kano Department of Pediatrics, Kobe Central Hospital, Kobe, Japan S. Osone Department of Pediatrics, Akashi City Hospital, Akashi, Japan K. Yagi : S. Todo Department of Pediatrics, Kyoto Prefectural University of Medicine, Kyoto, Japan Y. Murakami : Y. Yamada Central Laboratory, Matsushita Memorial Hospital, Moriguchi, Japan H. Yamada : S. Satomura New Diagnostics Business and Technology Development Operations, Wako Pure Chemical Industries, Ltd., Osaka, Japan