Several FGF23 immunoassays are available. However, they are reserved for research purposes as none have been approved for clinical use. We evaluated the performances of a new automated assay for intact FGF23 on the DiaSorin Liaison platform which is approved for clinical use. We established reference values in 908 healthy French subjects aged 18–89 years, and measured iFGF23 in patients with disorders of phosphate metabolism and in patients with chronic kidney disease (CKD). Intra-assay CV was 1.04–2.86% and inter-assay CV was 4.01–6.3%. The limit of quantification was <10 ng/L. Serum iFGF23 concentrations were considerably lower than EDTA values highlighting the importance of using exclusively EDTA plasma. Liaison iFGF23 values were approximately 25% higher than Immutopics values. In the 908 healthy subjects, distribution of the Liaison iFGF23 values was Gaussian with a mean ± 2SD interval of 22.7–93.1 ng/L. Men had a slightly higher level than women (60.3 ± 17.6 and 55.2 ± 17.2 ng/L, respectively). Plasma iFGF23 concentration in 11 patients with tumour-induced osteomalacia, 8 patients with X-linked hypophosphatemic rickets, 43 stage 3a, 43 stage 3b, 43 stage 4, 44 stage 5 CKD patients, and 44 dialysis patients were 217.2 ± 144.0, 150.9 ± 28.6, 98.5 ± 42.0, 130.8 ± 88.6, 130.8 ± 88.6, 331.7 ± 468.2, 788.8 ± 1306.6 and 6103.9 ± 11,178.8 ng/L, respectively. This new iFGF23 assay available on a platform that already allows the measurement of other important parameters of the mineral metabolism is a real improvement for the laboratories and clinicians/researchers involved in this field.
FGF23 Reference values Vitamin D Chronic kidney disease Hypophosphatemia Hyperphosphatemia
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Compliance with Ethical Standards
Conflict of interest
JCS reports lecture fees and/or travel/hotel expenses from DiaSorin, Roche Diagnostics, Abbott, Amgen, Shire, MSD, Lilly and Rottapharm; EC is a consultant for IDS and DiaSorin and has received lecture fees from IDS, DiaSorin, Roche, Abbott and Amgen; PD is a consultant for IDS and has received lecture fees and/or travel expenses from DiaSorin, Amgen, Shire, Fresenius, Menarini and Sanofi; DP, M-LP, AR and PC have nothing to disclose.
Human and Animal Rights and Informed Consent
All procedures performed in our patients/healthy subjects were in accordance with the ethical standards of the national research committee and with the 1964 Helsinki declaration and its latter amendments or comparable ethical standards. All healthy subjects and patients gave informed consent to have their blood sample tested.
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1.Service des Explorations FonctionnellesG.H. Necker Enfants MaladesParis cedex 15France
2.Service d’Endocrinologie pédiatrique, French Reference Center for Rare Disorders of the Mineral Metabolism, Department of Endocrinology and Diabetology for ChildrenHôpital Bicêtre, Assistance Publique-Hôpitaux de ParisLe Kremlin BicêtreFrance
3.Department of Nephrology-Dialysis-TransplantationUniversity of LiègeLiègeBelgium
4.Service d’Endocrinologie et des Maladies de la ReproductionAssistance Publique-Hôpitaux de Paris, Hôpitaux Universitaires Paris-Sud, Hôpital de BicêtreLe Kremlin BicêtreFrance
5.INSERM 1185, Fac Med Paris SudUniv Paris-Sud, Université Paris-SaclayLe Kremlin BicêtreFrance
6.Department of Clinical ChemistryUniversity of LiègeLiègeBelgium