BACKGROUND: Fibroblast growth factor-23 (FGF-23) is a bone secreted hormone that regulates phosphate homeostasis and calcitriol levels. FGF-23 concentrations are elevated in chronic kidney disease (CKD), oncogenic osteomalcia and a number of rare hereditary disorders. Studies systematically evaluating the pre-analytical stability of intact FGF-23 are lacking. METHODS: The stability of FGF-23 was assessed in timed experiments using blood taken into K2-EDTA plasma specimen tubes from a group of healthy participants and from a group with mild-to-moderate CKD. We evaluated the use of aprotinin, a serine protease inhibitor, and a commercially available protease inhibitor cocktail to preserve intact FGF-23 after blood collection. FGF-23 measurements were made using both intact and C-terminal assays. RESULTS: Both whole blood and separated sample studies demonstrated a rapid loss of intact FGF-23 within 2 h, while concentrations increased using the C-terminal assay. The addition of protease inhibitor cocktail stabilised FGF-23 concentrations for 4 h after blood collection. Intact and C-terminal assay FGF-23 measurements showed poor correlation in both healthy and CKD cohorts. CONCLUSION: K2-EDTA plasma samples, even when promptly separated, are unsuitable for measurement of FGF-23 unless stabilised with a protease inhibitor cocktail.
BACKGROUND:Fibroblast growth factor-23 (FGF-23) is a bone secreted hormone that regulates phosphate homeostasis and calcitriol levels. FGF-23 concentrations are elevated in chronic kidney disease (CKD), oncogenic osteomalcia and a number of rare hereditary disorders. Studies systematically evaluating the pre-analytical stability of intact FGF-23 are lacking. METHODS: The stability of FGF-23 was assessed in timed experiments using blood taken into K2-EDTA plasma specimen tubes from a group of healthy participants and from a group with mild-to-moderate CKD. We evaluated the use of aprotinin, a serine protease inhibitor, and a commercially available protease inhibitor cocktail to preserve intact FGF-23 after blood collection. FGF-23 measurements were made using both intact and C-terminal assays. RESULTS: Both whole blood and separated sample studies demonstrated a rapid loss of intact FGF-23 within 2 h, while concentrations increased using the C-terminal assay. The addition of protease inhibitor cocktail stabilised FGF-23 concentrations for 4 h after blood collection. Intact and C-terminal assay FGF-23 measurements showed poor correlation in both healthy and CKD cohorts. CONCLUSION:K2-EDTA plasma samples, even when promptly separated, are unsuitable for measurement of FGF-23 unless stabilised with a protease inhibitor cocktail.
Authors: Christopher T Sempos; Annemieke C Heijboer; Daniel D Bikle; Jens Bollerslev; Roger Bouillon; Patsy M Brannon; Hector F DeLuca; Glenville Jones; Craig F Munns; John P Bilezikian; Andrea Giustina; Neil Binkley Journal: Br J Clin Pharmacol Date: 2018-07-17 Impact factor: 4.335
Authors: Casey M Rebholz; Morgan E Grams; Josef Coresh; Elizabeth Selvin; Lesley A Inker; Andrew S Levey; Paul L Kimmel; Ramachandran S Vasan; John H Eckfeldt; Harold I Feldman; Chi-Yuan Hsu; Pamela L Lutsey Journal: J Am Soc Nephrol Date: 2014-07-24 Impact factor: 10.121
Authors: D El-Maouche; C E Dumitrescu; P Andreopoulou; R I Gafni; B A Brillante; N Bhattacharyya; N S Fedarko; M T Collins Journal: Osteoporos Int Date: 2016-02-29 Impact factor: 4.507
Authors: Anna Jovanovich; Petra Bùzková; Michel Chonchol; John Robbins; Howard A Fink; Ian H de Boer; Bryan Kestenbaum; Ronit Katz; Laura Carbone; Jennifer Lee; Gail A Laughlin; Kenneth J Mukamal; Linda F Fried; Michael G Shlipak; Joachim H Ix Journal: J Clin Endocrinol Metab Date: 2013-06-14 Impact factor: 5.958