Instability of fibroblast growth factor-23 (FGF-23): implications for clinical studies.
Author(s): Smith ER, Ford ML, Tomlinson LA, Weaving G, Rocks BF, Rajkumar C, Holt SG
Publication: Clin Chim Acta, 2011, Vol. 412, Page 1008-11
PubMed ID: 21324311 PubMed Review Paper? No
Purpose of Paper
The purpose of this paper was to determine the effects of room temperature storage of K2EDTA whole blood and plasma, with and without protease inhibitors, on levels on intact (N-terminal) and C-terminal fibroblast growth factor (FGF)-23 in healthy individuals and patients with chronic kidney disease (CKD).
Conclusion of Paper
With storage of whole blood or plasma at room temperature, intact FGF-23 declined after 2 h and C-terminal FGF-23 increased after 30 min. Protease inhibitor cocktail completely stabilized intact and C-terminal FGF-23, but aprotinin only partially stabilized intact and C-terminal FGF-23 levels. Baseline levels of intact and C-terminal FGF-23 were 2-3 fold higher in patients with CKD than in healthy individuals, and the relative changes in intact and C-terminal FGF-23 levels with storage were larger in patients with CKD than in healthy individuals.
Studies
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Study Purpose
The purpose of this study was to determine the effects of up to 4 h room temperature storage of K2EDTA whole blood and plasma, with and without protease inhibitor cocktail or aprotinin, on levels of intact and C-terminal FGF-23 in healthy individuals and patients with CKD. After experimental storage plasma and whole blood specimens were frozen and stored at -70 degrees C prior to analysis.
Summary of Findings:
Intact FGF-23 levels measured in plasma declined at similar rates when whole blood or plasma specimens were stored at room temperature for 4 h (both p<0.001). In contrast using the C-terminal assay FGF-23 increased in plasma and whole blood stored at room temperature for 2 h (both p<0.001) or more. Intact and C-terminal FGF-23 levels in both blood and plasma were stabilized for at least 4 h by the addition of protease inhibitor cocktail, but aprotinin only partially stabilized intact and C-terminal FGF-23 levels (each <30% change over 4 h). Baseline levels of intact and C-terminal FGF-23 were 2-3 fold higher in patients with CKD than in healthy individuals, and the relative changes in intact and C-terminal FGF-23 levels in unstabilized whole blood and plasma with storage were larger in patients with CKD than in healthy individuals. In stabilized specimens from healthy individuals, there was only a weak association (r2=0.186) between intact and c-terminal FGF-23 levels, but in patients with CKD, the association between intact and c-terminal FGF-23 was moderate (r2=0.428).
Biospecimens
Preservative Types
- Frozen
Diagnoses:
- Normal
- Other diagnoses
Platform:
Analyte Technology Platform Protein ELISA Peptide ELISA Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Storage Time at room temperature 30 min
2 h
4 h
Biospecimen Aliquots and Components Blood and blood products Plasma
Whole blood
Preaquisition Diagnosis/ patient condition Chronic kidney disease
Healthy
Analyte Extraction and Purification Protease inhibitor Aprotinin
Cocktail
ELISA Specific Targeted peptide/protein N-terminal FGF-23
C-terminal FGF-23