Hogewind-Schoonenboom Jacomine E, Huang Lisha, de Groof Femke, Zhu Li, Voortman Gardi J, Schierbeek Henk, Vermes Andras, Chen Chao, Huang Ying, van Goudoever Johannes B
*Department of Pediatrics, Academic Medical Centre, Emma Children's Hospital, Amsterdam †Department of Pediatrics, Division of Neonatology, Erasmus Medical Centre, Sophia Children's Hospital, Rotterdam §Department of Pediatrics, Division of Neonatology, Children's Hospital of Fudan University, Shanghai, PR China ||Hospital Pharmacy, Erasmus Medical Centre, Rotterdam, The Netherlands ¶Department of Pediatrics, Division of Gastroenterology, Children's Hospital of Fudan University, Shanghai, PR China.
J Pediatr Gastroenterol Nutr. 2015 Sep;61(3):373-9. doi: 10.1097/MPG.0000000000000807.
Threonine is one of the essential amino acids. Its major fate is incorporation into intestinal mucosal proteins and synthesis of secretory glycoproteins. Therefore, it has an important function in the neonatal gut barrier integrity. The objective was to quantify the threonine requirement in fully enterally fed term neonates by means of the indicator amino acid oxidation (IAAO) method, using L-[1-C]phenylalanine as indicator.
After a 24-hour test diet adaptation, containing randomly assigned amounts of threonine (range 5-182 mg · kg · day), the participating neonates received a primed continuous infusion of [C]bicarbonate and L-[1-C]phenylalanine. At baseline and during the plateau phase of both infusions, breath samples were obtained for CO2. The fractional L-[1-C]phenylalanine oxidation (FCO2) was estimated and plotted against the threonine intakes. Biphasic linear regression crossover analysis was used to calculate the breakpoint of the FCO2, representing the mean threonine requirement. Data are presented as mean ± SD.
Thirty-two term neonates (gestational age 39 ± 1 weeks, birth weight 3.3 ± 0.3 kg, mean postnatal age 10 ± 4 days) were studied. The mean threonine requirement was estimated to be 68 mg · kg · day with an upper and lower 95% confidence interval of 104 and 32 mg · kg · day, respectively (r = 0.37).
The determined threonine requirement is extremely close to the existing requirement recommendations (∼90% of the present World Health Organization requirement guidelines). Infant formula preparations presently on the market, however, contain up to twice as much threonine as recommended. The threonine intake in formula-fed infants may therefore be reduced considerably.
苏氨酸是必需氨基酸之一。其主要去向是掺入肠黏膜蛋白并合成分泌性糖蛋白。因此，它在新生儿肠道屏障完整性方面具有重要作用。目的是通过指示剂氨基酸氧化（IAAO）法，以L-[1-¹³C]苯丙氨酸作为指示剂，定量全肠道喂养足月儿的苏氨酸需求量。
在适应含随机分配量苏氨酸（范围为5 - 182 mg·kg·天）的24小时试验饮食后，参与研究的新生儿接受[¹³C]碳酸氢盐和L-[1-¹³C]苯丙氨酸的首剂持续输注。在两种输注的基线期和平台期，采集呼气样本用于检测二氧化碳。估算L-[1-¹³C]苯丙氨酸氧化分数（FCO₂），并将其与苏氨酸摄入量作图。采用双相线性回归交叉分析计算FCO₂的转折点，该转折点代表平均苏氨酸需求量。数据以均值±标准差表示。
研究了32名足月儿（胎龄39±1周，出生体重3.3±0.3 kg，平均出生后年龄10±4天）。估计平均苏氨酸需求量为68 mg·kg·天，95%置信区间上限和下限分别为104和32 mg·kg·天（r = 0.37）。
确定的苏氨酸需求量与现有需求建议极为接近（约为世界卫生组织当前需求指南的90%）。然而，目前市场上的婴儿配方奶粉制剂中苏氨酸含量高达推荐量的两倍。因此，配方奶喂养婴儿的苏氨酸摄入量可大幅降低。
