A Novel CLEIA for FGF23
Ito, Nobuaki The University of Tokyo
Kubota, Takuo Osaka University
Kitanaka, Sachiko University of Tokyo
Fujiwara, Ikuma Tohoku University
Adachi, Masanori Kanagawa Children's Medical Center
Takeuchi, Yasuhiro Toranomon Hospital|Okinaka Memorial Institute for Medical Research
Yamagami, Hitomi Minaris Medical
Kimura, Takehide Minaris Medical
Shinoda, Tatsuya Minaris Medical
Minagawa, Masanori Chiba Children's Hospital
Okazaki, Ryo Teikyo University
Ozono, Keiichi Osaka University
Seino, Yoshiki Osaka Hospital|Japan Community Healthcare Organization
Pulmonary small cell carcinoma
Prostate small cell carcinoma
Introduction: Measurement of fibroblast growth factor 23 (FGF23) has been reported to be clinically useful for the differential diagnosis of chronic hypophosphatemia. However, assays for research use only are available in Japan. Thus, the objective of this study was to examine the clinical utility of a novel and automated chemiluminescent enzyme immunoassay for the measurement of FGF23.
Materials and Methods: Participants were recruited from July 2015 to January 2017 at six facilities in Japan. Thirty-eight patients with X-linked hypophosphatemic rickets (XLH; 15 males, 23 females, age 0–66 years), five patients with tumour-induced osteomalacia (TIO; 3 males, 2 females, age 60–73 years), and twenty-two patients with hypophosphatemia (11 males, 11 females, age 1–75 years) caused due to other factors participated in this study.
Results: With the clinical cut-off value of FGF23 at 30.0 pg/mL indicated in the Diagnostic Guideline of Rickets/Osteomalacia in Japan, the sensitivity and specificity of FGF23-related hypophosphatemic rickets/osteomalacia without vitamin D deficiency (disease group-1) were 100% and 81.8%, respectively, which distinguished it from non-FGF23-related hypophosphatemia (disease group-2). Furthermore, the diagnostic sensitivity of FGF23-related hypophosphatemia with vitamin D deficiency remained at 100%. Among the four patients with FGF23 levels ≥ 30.0 pg/mL in disease group-2, two patients with relatively higher FGF23 values were suspected to have genuine FGF23-related hypophosphatemia, due to the ectopic production of FGF23 in pulmonary and prostate small cell carcinomas.
Conclusion: The novel FGF23 assay tested in this study is useful for the differential diagnosis of hypophosphatemic rickets/osteomalacia in a clinical setting.
Journal of Bone and Mineral Metabolism
The Japanese Society for Bone and Mineral Research|Springer Nature
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Institute of Advanced Medical Sciences