As citric acid and
sodium citrate hinder the actual uricase-based UA measurement, therefore
instead of ACD and SC tubes, SST tubes should prefer while detecting serum UA,
evident from the findings of a newly issued study in the Journal of
Pharmaceutical and Biomedical Analysis. After noting considerable differences
between UA concentrations of blood samples collected by different collection
tubes, this study was led to determine the impact of exogenous tube components
on calculated UA concentrations.
Blood samples were obtained in Sodium Citrate (SC) tubes, Serum Separator Tubes
(SST tubes), and Acid Citrate Dextrose (ACD) tubes and uricase method was used
to measure the circulating UA concentrations. Impact of dextrose, citric acid
and sodium citrate in the presence of peroxidase, violet dye, and hydrogen
peroxide determined by absorbance assays.
As compared to the SST tubes, UA concentrations collected in ACD and SC tubes
were found to be lower. Further, different concentration of citric acid,
dextrose and sodium citrate demonstrated significantly lower UA measurements
than controls. In the presence of leuco crystal violet, hydrogen peroxide, and
peroxidase, absorbance assays showed that increased concentrations of citric
acid and sodium citrate associated with the reduced amount of oxidized dye in
the uricase method of UA measurement in a dose-dependent manner. The reason
behind this was the scavenging of hydrogen peroxide by citric acid, and this
reduces the quantity of oxidized leuco dye which leads to false low UA
measurements. However, dextrose was not associated with the altered amount of
oxidized dye. Therefore, the ACD and SC tubes should not be used while
measuring the UA through uricase measurement methods.
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