Zamora Tara G, Guiang Sixto F, Widness John A, Georgieff Michael K
Children's Hospitals and Clinics of Minnesota, St Paul, Minnesota, USA.
Department of Pediatrics, University of Minnesota School of Medicine, Minneapolis, Minnesota, USA.
Pediatr Res. 2016 Jun;79(6):922-8. doi: 10.1038/pr.2016.20. Epub 2016 Feb 11.
Critically ill preterm and term neonates are at high risk for negative iron balance due to phlebotomy that occurs with frequent laboratory monitoring, and the high iron demand of rapid growth. Understanding the prioritization of iron between red blood cells (RBCs) and brain is important given iron's role in neurodevelopment.
Ten neonatal twin lamb pairs (n = 20) underwent regular phlebotomy for 11 d. Lambs were randomized to receive no iron or i.v. daily iron supplementation from 1 to 5 mg/kg. Serum hemoglobin concentration and reticulocyte count were assayed, iron balance calculated, and iron content of RBCs, liver, brain, muscle, and heart measured at autopsy.
Among phlebotomized lambs: (i) liver iron concentration was directly related to net iron balance (r = 0.87; P < 0.001) and (ii) brain iron concentration was reduced as a function of net iron balance (r = 0.63) only after liver iron was depleted. In animals with negative iron balance, total RBC iron was maintained while brain iron concentration decreased as a percentage of the iron present in RBCs (r = -0.70; P < 0.01) and as a function of reticulocyte count (r = -0.63; P < 0.05).
Phlebotomy-induced negative iron balance limits iron availability to the developing brain.
危重新生早产儿和足月儿由于频繁实验室监测导致的静脉穿刺放血以及快速生长对铁的高需求，处于铁负平衡的高风险中。鉴于铁在神经发育中的作用，了解红细胞（RBC）和大脑之间铁的优先分配情况很重要。
十对新生双胎羔羊（n = 20）接受了为期11天的定期静脉穿刺放血。羔羊被随机分为不补铁组或静脉每日补充1至5mg/kg铁剂组。测定血清血红蛋白浓度和网织红细胞计数，计算铁平衡，并在尸检时测量RBC、肝脏、大脑、肌肉和心脏的铁含量。
在接受静脉穿刺放血的羔羊中：（i）肝脏铁浓度与净铁平衡直接相关（r = 0.87；P < 0.001），并且（ii）仅在肝脏铁耗尽后，大脑铁浓度才作为净铁平衡的函数而降低（r = 0.63）。在铁负平衡的动物中，RBC总铁含量得以维持，而大脑铁浓度作为RBC中铁含量的百分比下降（r = -0.70；P < 0.01），并作为网织红细胞计数的函数下降（r = -0.63；P < 0.05）。
静脉穿刺放血引起的铁负平衡限制了发育中大脑的铁供应。
