Preanalytical study of fetuin-A: effect of sample type, processing speed and freeze-thaw cycles.
BACKGROUND
It has been suggested that fetuin-A may be a potential biomarker of cardiometabolic disease. However, few studies have investigated preanalytical factors that might impact the measurement of fetuin-A in the circulation. This pilot study aimed to investigate the preanalytical variables of sample type, timing of sample centrifugation and the impact of freeze-thaw cycles on the concentration of fetuin-A in serum or EDTA-plasma.


METHODS
Blood samples were taken from 19 male or female healthy volunteers, aged 18-70 years, and left at ambient room temperature for 2 h or 48 h. The tubes were then centrifuged, serum and EDTA-plasma separated, and fetuin-A concentrations measured using a commercially available enzyme-linked immunosorbent assay (ELISA).


RESULTS
There was no significant difference between the concentrations of fetuin-A in EDTA-plasma and serum following separation from whole blood at 2 h postcollection (P=0.78). The median (interquartile range) concentrations of fetuin-A in EDTA-plasma separated at 2 h and 48 h postcollection were 589 µg/mL (484-703 µg/mL) and 767 µg/mL (687-942 µg/mL), respectively (P<0.0005). For serum, equivalent concentrations were 606 µg/mL (501-669 µg/mL) at 2 h and 607 µg/mL (564-757 µg/mL) at 48 h postcollection (P=0.06). Fetuin-A concentrations measured in EDTA-plasma and serum showed no significant change following three freeze-thaw cycles in samples separated at 2 h postcollection (EDTA-plasma P=0.16; serum P=0.89).


CONCLUSIONS
This small pilot study has shown that serum is preferable to EDTA-plasma for the measurement of fetuin-A. It has also shown that fetuin-A appears to be as stable after three freeze-thaw cycles as it is after one.
BHF Glasgow Cardiovascular Research Centre, Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, UK.
Lisa
L
McArthur
BHF Glasgow Cardiovascular Research Centre, Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, UK.
Lisa
L
Johnston
BHF Glasgow Cardiovascular Research Centre, Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, UK.
Naveed
N
Sattar
BHF Glasgow Cardiovascular Research Centre, Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, UK.
Jennifer
J
Logue
BHF Glasgow Cardiovascular Research Centre, Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, UK Paul.Welsh@glasgow.ac.uk.
Paul
P
Welsh
D000293:Adolescent; D000328:Adult; D000368:Aged; D004492:Edetic Acid / Q000737:chemistry; D004797:Enzyme-Linked Immunosorbent Assay / Q000592:standards*; D005260:Female; D005615:Freezing; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D010949:Plasma; D044967:Serum; D013696:Temperature; D060749:alpha-2-HS-Glycoprotein / Q000032:analysis*
C556354:AHSG protein, human; D060749:alpha-2-HS-Glycoprotein; D004492:Edetic Acid
Fetuin-A; freeze-thaw cycles; plasma; preanalytical variables; serum