Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, United States.
Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, United States; Seattle Children's Hospital, Seattle, WA, United States.
Clin Biochem. 2022 Jan;99:111-117. doi: 10.1016/j.clinbiochem.2021.10.005. Epub 2021 Oct 19.
The measurement of plasma concentrations of retinol binding protein is a component of nutritional assessment in neonatal intensive care. However, serial testing in newborns is hampered by the limited amount of blood that can be sampled. Limitations are most severe with preterm infants, for whom close monitoring may be most important.
We developed an assay to quantify retinol binding protein using trypsin digestion and liquid chromatography-tandem mass spectrometry, which requires a serum or plasma volume of 5 µl. Additionally, we validated the method according to current recommendations and performed comparison with a standard nephelometry platform in clinical use.
The assay demonstrated linearity from below 1 mg/dL (0.48 µM) to more than 20 mg/dL (9.7 µM), and an imprecision of 11.8% at 0.43 mg/dL (0.21 µM). The distribution of results observed with the new method was different when compared with nephelometry.
Liquid chromatography-tandem mass spectrometry facilitated testing a smaller sample volume, thereby increasing the ability to monitor key nutritional markers in premature infants. The differences in results compared with a commercially-available nephelometric assay revealed questionable results for lower concentrations by immunoassay.
视黄醇结合蛋白的血浆浓度测量是新生儿重症监护营养评估的一个组成部分。然而，由于新生儿可以采集的血量有限，因此对其进行连续检测存在困难。早产儿的限制最为严重，因为对他们的密切监测可能是最重要的。
我们开发了一种使用胰蛋白酶消化和液相色谱-串联质谱法来定量视黄醇结合蛋白的检测方法，该方法仅需 5µl 的血清或血浆量。此外，我们根据当前的建议验证了该方法，并与临床使用的标准散射比浊平台进行了比较。
该检测方法在低于 1mg/dL（0.48µM）至超过 20mg/dL（9.7µM）的范围内显示出线性，在 0.43mg/dL（0.21µM）时的精密度为 11.8%。与散射比浊法相比，新方法观察到的结果分布不同。
液相色谱-串联质谱法可用于检测更小的样本量，从而提高监测早产儿关键营养标志物的能力。与市售的散射比浊测定法相比，结果存在差异，表明免疫测定法对较低浓度的结果存在疑问。
