Milcent Karen, Poulalhon Claire, Fellous Christelle Vauloup, Petit François, Bouyer Jean, Gajdos Vincent
Clin Lab. 2014;60(11):1921-4. doi: 10.7754/clin.lab.2014.140307.
The aim was to assess procalcitonin (PCT) stability after two days of storage at room temperature.
Samples were collected from febrile children aged 7 to 92 days and were rapidly frozen after sampling. PCT levels were measured twice after thawing: immediately (named y) and 48 hours later after storage at room temperature (named x). PCT values were described with medians and interquartile ranges or by categorizing them into classes with thresholds 0.25, 0.5, and 2 ng/mL. The relationship between x and y PCT levels was analyzed using fractional polynomials in order to predict the PCT value immediately after thawing (named y') from x.
A significant decrease in PCT values was observed after 48 hours of storage at room temperature, either in median, 30% lowering (p < 0.001), or as categorical variable (p < 0.001). The relationship between x and y can be accurately modeled with a simple linear model: y = 1.37 x (R2 = 0.99). The median of the predicted PCT values y' was quantitatively very close to the median of y and the distributions of y and y' across categories were very similar and not statistically different.
PCT levels noticeably decrease after 48 hours of storage at room temperature. It is possible to pre- dict accurately effective PCT values from the values after 48 hours of storage at room temperature with a simple statistical model.
目的是评估降钙素原（PCT）在室温下储存两天后的稳定性。
收集7至92日龄发热儿童的样本，采样后迅速冷冻。解冻后测量两次PCT水平：立即测量（称为y）以及在室温下储存48小时后测量（称为x）。PCT值用中位数和四分位间距描述，或者通过将其分类为阈值为0.25、0.5和2 ng/mL的类别来描述。使用分数多项式分析x和y PCT水平之间的关系，以便从x预测解冻后立即的PCT值（称为y'）。
在室温下储存48小时后，观察到PCT值显著下降，无论是中位数下降30%（p < 0.001），还是作为分类变量（p < 0.001）。x和y之间的关系可以用简单线性模型准确建模：y = 1.37x（R2 = 0.99）。预测的PCT值y'的中位数在数量上非常接近y的中位数，并且y和y'在各分类中的分布非常相似且无统计学差异。
PCT水平在室温下储存48小时后明显下降。使用简单统计模型可以根据室温下储存48小时后的PCT值准确预测有效PCT值。
