Schmiedchen Bettina, Longardt Ann Carolin, Bührer Christoph, Raila Jens, Loui Andrea, Schweigert Florian J
Department of Physiology and Pathophysiology, University of Potsdam, Nuthetal, Germany.
Neonatology. 2014;105(2):155-60. doi: 10.1159/000356773. Epub 2013 Dec 18.
The relative dose response (RDR) test, which quantifies the increase in serum retinol after vitamin A administration, is a qualitative measure of liver vitamin A stores. Particularly in preterm infants, the feasibility of the RDR test involving blood is critically dependent on small sample volumes.
This study aimed to assess whether the RDR calculated with retinol-binding protein 4 (RBP4) might be a substitute for the classical retinol-based RDR test for assessing vitamin A status in very preterm infants.
This study included preterm infants with a birth weight below 1,500 g (n = 63, median birth weight 985 g, median gestational age 27.4 weeks) who were treated with 5,000 IU retinyl palmitate intramuscularly 3 times a week for 4 weeks. On day 3 (first vitamin A injection) and day 28 of life (last vitamin A injection), the RDR was calculated and compared using serum retinol and RBP4 concentrations.
The concentrations of retinol (p < 0.001) and RBP4 (p < 0.01) increased significantly from day 3 to day 28. On day 3, the median (IQR) retinol-RDR was 27% (8.4-42.5) and the median RBP4-RDR was 8.4% (-3.4 to 27.9), compared to 7.5% (-10.6 to 20.8) and -0.61% (-19.7 to 15.3) on day 28. The results for retinol-RDR and RBP4-RDR revealed no significant correlation. The agreement between retinol-RDR and RBP4-RDR was poor (day 3: Cohen's κ = 0.12; day 28: Cohen's κ = 0.18).
The RDR test based on circulating RBP4 is unlikely to reflect the hepatic vitamin A status in preterm infants.
相对剂量反应（RDR）试验通过测定维生素A给药后血清视黄醇的增加量来定量评估肝脏维生素A储备。特别是对于早产儿，涉及血液样本量少的RDR试验的可行性至关重要。
本研究旨在评估用视黄醇结合蛋白4（RBP4）计算的RDR是否可替代经典的基于视黄醇的RDR试验，用于评估极早产儿的维生素A状况。
本研究纳入了出生体重低于1500g的早产儿（n = 63，中位出生体重985g，中位胎龄27.4周），这些婴儿每周接受3次5000IU棕榈酸视黄酯肌肉注射，共4周。在出生第3天（首次维生素A注射）和出生第28天（最后一次维生素A注射），使用血清视黄醇和RBP4浓度计算并比较RDR。
从第3天到第28天，视黄醇（p < 0.001）和RBP4（p < 0.01）浓度显著增加。第3天，视黄醇-RDR的中位数（IQR）为27%（8.4 - 42.5），RBP4-RDR的中位数为8.4%（-3.4至27.9），而第28天分别为7.5%（-10.6至20.8）和-0.61%（-19.7至15.3）。视黄醇-RDR和RBP4-RDR的结果显示无显著相关性。视黄醇-RDR和RBP4-RDR之间的一致性较差（第3天：Cohen's κ = 0.12；第28天：Cohen's κ = 0.18）。
基于循环RBP4的RDR试验不太可能反映早产儿的肝脏维生素A状况。
