Instability of fibroblast growth factor-23 (FGF-23): implications for clinical studies

Smith, Edward R, Ford, Martin L, Tomlinson, Laurie A, Weaving, Gary, Rocks, Bernard F, Rajkumar, Chakravarthi and Holt, Stephen G (2011) Instability of fibroblast growth factor-23 (FGF-23): implications for clinical studies. Clinica Chimica Acta, 412 (11-12). pp. 1008-1011. ISSN 1873-3492

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Abstract

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.

Item Type: Article
Schools and Departments: Brighton and Sussex Medical School > Clinical and Experimental Medicine
Subjects: R Medicine > RC Internal medicine > RC0581 Specialties of internal medicine > RC0952 Geriatrics
Depositing User: Simone Breckell
Date Deposited: 30 Apr 2013 13:21
Last Modified: 30 Apr 2013 13:21
URI: http://sro.sussex.ac.uk/id/eprint/44548
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