Bender George Jesse, Cashore William James, Oh William
Department of Pediatrics, Brown Medical School, Women and Infants' Hospital of Rhode Island, 100 Dudley St, Providence, RI 02860, USA.
Pediatrics. 2007 Nov;120(5):1067-73. doi: 10.1542/peds.2006-3024.
Bilirubin is toxic to the brain and enters the brain in unbound form. Serum unconjugated, unbound bilirubin may be a good predictor of bilirubin encephalopathy. Unbound bilirubin levels may depend on the bilirubin-binding capacity of albumin, which has not been described for neonates of <28 weeks' gestation.
The purpose of this work was to determine the ontogeny of bilirubin-binding capacity and the effect of clinical status in very preterm neonates.
A total of 152 neonates (23-31 weeks' gestational age; 440-1300 g) were enrolled prospectively. At 5 days of age, total serum bilirubin and unbound bilirubin were measured with the unbound bilirubin-A1 analyzer (Arrows Co, Osaka, Japan) and albumin with the Bromocresol-purple method. Scatchard plots were used to estimate bilirubin-binding affinity and capacity. Clinical status for each infant was rated as high, moderate, or low risk by using a modified Score for Neonatal Acute Physiology model. Low risk was considered clinically stable.
Unbound bilirubin has a significant, direct correlation to total bilirubin and is greater in unstable than in stable neonates. For the entire cohort, bilirubin-binding capacity had a direct relationship to gestational age. The bilirubin-binding capacities of infants in the low- and high-risk groups also had a direct relationship to gestational age. Bilirubin-binding capacity was greater in the low-risk group (20.8 +/- 4.6 mg/dL; 356 +/- 79 micromol/L) than in the moderate- (17.8 +/- 3.5 mg/dL; 304 +/- 60 micromol/L) or high- (17.3 +/- 3.4 mg/dL; 296 +/- 58 micromol/L) risk groups. Bilirubin-binding affinity did not differ by clinical risk status or gestational age.
In very preterm, very low birth weight infants, bilirubin-binding capacity is directly proportional to gestational age. Bilirubin-binding capacity is lower and unbound bilirubin higher in unstable than in stable neonates. These data may be useful in guiding the management of hyperbilirubinemia in very low birth weight infants.
胆红素对大脑有毒性，以未结合形式进入大脑。血清未结合、未与白蛋白结合的胆红素可能是胆红素脑病的良好预测指标。未结合胆红素水平可能取决于白蛋白的胆红素结合能力，而对于孕周小于28周的新生儿，尚未对此进行描述。
本研究旨在确定极早产儿胆红素结合能力的个体发育情况以及临床状态对其的影响。
前瞻性纳入152例新生儿（胎龄23 - 31周；体重440 - 1300克）。在出生后5天时，使用未结合胆红素 - A1分析仪（日本大阪Arrows公司）测定总血清胆红素和未结合胆红素，采用溴甲酚紫法测定白蛋白。用Scatchard图估计胆红素结合亲和力和能力。采用改良的新生儿急性生理学评分模型将每个婴儿的临床状态分为高、中、低风险。低风险被认为临床稳定。
未结合胆红素与总胆红素呈显著正相关，且不稳定新生儿中的未结合胆红素高于稳定新生儿。对于整个队列，胆红素结合能力与胎龄呈正相关。低风险组和高风险组婴儿的胆红素结合能力也与胎龄呈正相关。低风险组的胆红素结合能力（20.8±4.6毫克/分升；356±79微摩尔/升）高于中风险组（17.8±3.5毫克/分升；304±60微摩尔/升）或高风险组（17.3±3.4毫克/分升；296±58微摩尔/升）。胆红素结合亲和力在不同临床风险状态或胎龄之间无差异。
在极早产、极低出生体重儿中，胆红素结合能力与胎龄成正比。不稳定新生儿的胆红素结合能力较低，未结合胆红素较高。这些数据可能有助于指导极低出生体重儿高胆红素血症的管理。
