Wastney M E, Angelus P A, Barnes R M, Subramanian K N
Department of Pediatrics, Georgetown University Medical Center, Washington, District of Columbia 20007, USA.
Pediatr Res. 1999 Feb;45(2):191-6. doi: 10.1203/00006450-199902000-00006.
Zinc (Zn) is an essential nutrient for growth, but little is known about Zn absorption, distribution, excretion, and retention in preterm infants. Nine infants with gestational age 32+/-1 wk (mean+/-SE), birth weight 1.44+/-0.08 kg, postnatal age 14+/-3 d, on Zn intake of 23+/-3 micromol/kg per d via enteral feeding of preterm formula were studied. A stable Zn isotope (70Zn) was administered orally or i.v., and plasma, red blood cells, urine, and feces were sampled for up to 30 d. Samples were analyzed for Zn by inductively coupled plasma atomic emission spectrometry and for isotope enrichment by inductively coupled plasma mass spectrometry. Data were analyzed by compartmental analysis using the Simulation Analysis and Modeling program, and absorption, distribution, excretion, and retention were calculated. Absorption was 36+/-5% or 7+/-1 micromol/kg per d; distribution in plasma was 15+/-1 micromol Zn/L and in RBC was 41+/-4 micromol Zn/L; excretion in urine was 0.55+/-0.03 micromol Zn/kg per d and in feces was 17+/-3 micromol Zn/kg per d and retention was 5+/-1 microl/kg per d. Results show that healthy preterm infants with Zn intake of 23 micromol/kg per d and expected growth rates (> 15 g/kg per d) absorb and retain Zn at rates comparable to in utero accretion. The values for absorption, distribution, and excretion by this population of healthy preterm infants provide a normal range for future studies, although further studies are required to determine endogenous excretion rates in healthy preterm infants. We speculate that these values can be used to determine whether Zn kinetics are abnormal in sick infants or in infants with slow growth.
锌（Zn）是生长所必需的营养素，但对于早产儿锌的吸收、分布、排泄和潴留情况知之甚少。研究了9例胎龄32±1周（均值±标准误）、出生体重1.44±0.08 kg、生后年龄14±3天的婴儿，这些婴儿通过肠内喂养早产儿配方奶，锌摄入量为每日23±3微摩尔/千克。口服或静脉注射稳定的锌同位素（70Zn），并在长达30天的时间内采集血浆、红细胞、尿液和粪便样本。通过电感耦合等离子体原子发射光谱法分析样本中的锌含量，通过电感耦合等离子体质谱法分析同位素富集情况。使用模拟分析与建模程序通过房室分析对数据进行分析，并计算吸收、分布、排泄和潴留情况。吸收率为36±5%或每日7±1微摩尔/千克；血浆中的分布量为15±1微摩尔锌/升，红细胞中的分布量为41±4微摩尔锌/升；尿中排泄量为每日0.55±0.03微摩尔锌/千克，粪便中排泄量为每日17±3微摩尔锌/千克，潴留量为每日5±1微升/千克。结果表明，锌摄入量为每日23微摩尔/千克且预期生长速率（>每日15克/千克）的健康早产儿吸收和潴留锌的速率与子宫内的蓄积速率相当。尽管需要进一步研究来确定健康早产儿的内源性排泄率，但这群健康早产儿的吸收、分布和排泄值为未来的研究提供了一个正常范围。我们推测这些值可用于确定患病婴儿或生长缓慢的婴儿的锌动力学是否异常。
