骨定量超声技术在早产儿骨发育评价中应用和影响早产儿骨发育因素的研究

目的 探讨定量超声(QUS)技术评价早产儿骨发育的作用及早产儿骨发育的影响因素.方法 选取2009年2～7月本院NICU住院的早产儿为观察组,按2:1比例随机选择同期出生的足月儿为对照组,用定量超声仪测量生后2 d之内胫骨声波速度(SOS),同时检测出生24 h内血钙、镁、磷和碱性磷酸酶,分析不同胎龄、体重、性别、母妊娠期高血压疾病及生化指标等因素对SOS值的影响,对有意义的因素进行多元回归分析.结果 (1)胫骨SOS值早产儿低于足月儿;胎龄≤30周早产儿低于胎龄34～36周早产儿和足月儿,胎龄31～33周早产儿低于胎龄34～36周早产儿和足月儿;出生体重<1500 g新生儿低于1500～2500 g和>2500 g的新生儿,P均<0.05;不同性别之间SOS值差异无统计学意义(P>0.05);早产适于胎龄儿低于早产小于胎龄儿,P<0.001:母妊娠期高血压疾病组早产儿高于非妊娠期高血压疾病组,P<0.05.(2)SOS值与胎龄(r=0.347,P<0.001)、母妊娠期高血压疾病(r=0.215,P=0.016)、宫内发育迟缓(r=0.367,P<0.001)、血钙(r=0.259,P=0.004)和血镁(r=0.234,P=0.008)正相关,与血磷(r=-0.201,P=0.025)负相关:多元回归分析发现胎龄、宫内发育迟缓和镁是影响SOS的重要因素(P<0.001).结论 QUS可以准确的评价胎儿骨营养状态,胎龄、宫内生长迟缓和镁是胎儿骨发育的重要影响因素.     

胎龄和体重及缺氧对新生儿纤溶活性的影响

目的　探讨正常新生儿的纤溶活性状态及胎龄、体重、缺氧对纤溶活性的影响 ,并分析新生儿出血的可能原因及风险因素。方法　对不同胎龄、不同出生体重正常新生儿以及出生窒息足月儿的纤溶酶原活性 (P1g)、组织型纤溶酶原激活物活性 (t PA)、纤溶酶原激活物抑制物活性 (PAI)及D 二聚体含量 (D dimer)进行检测。结果　正常足月新生儿P1g为 (2 84± 0 0 6)IU/ml,t PA为 (0 2 4±0 11)IU/ml,PAI为 (0 64± 0 3 7)AU/ml,PAI/t PA比值为 2 6± 2 0 ,D dimer为 (3 7± 4 7)mg/L ,表现出较宽的取值范围。无合并症早产儿P1g活性为 (2 16± 0 5 2 )IU/ml,D dimer含量为 (1 0± 0 7)mg/L ,PAI/t PA比值为 3 9± 2 6;与正常足月儿相比 ,P1g活性和D dimer含量显著降低 (P <0 0 1) ,PAI/t PA比值显著增高 (P <0 0 5 ) ;窒息足月儿与无合并症早产儿相似 ,P1g活性、D dimer含量为 (1 2 0±0 85 )mg/L ;与足月儿相比 ,P1g活性和D dimer含量亦显著降低 ,而PAI/t PA比值显著增高 ,出生后窒息时间与D dimer含量呈显著正相关 (r=0 5 96,P <0 0 1) ;P1g活性、胎龄、出生体重与D dimer含量均呈显著正相关。结论　正常足月儿纤溶活性有较大个体差异 ;纤溶活性的改变和胎龄、出生体重、缺氧密切相关。纤溶活性     

骨定量超声技术在早产儿骨发育评价中应用和影响早产儿骨发育因素的研究

目的探讨定量超声(QUS)技术评价早产儿骨发育的作用及早产儿骨发育的影响因素。方法选取2009年2～7月本院NICU住院的早产儿为观察组,按2∶1比例随机选择同期出生的足月儿为对照组,用定量超声仪测量生后2d之内胫骨声波速度(SOS),同时检测出生24h内血钙、镁、磷和碱性磷酸酶,分析不同胎龄、体重、性别、母妊娠期高血压疾病及生化指标等因素对SOS值的影响,对有意义的因素进行多元回归分析。结果(1)胫骨SOS值早产儿低于足月儿;胎龄≤30周早产儿低于胎龄34～36周早产儿和足月儿,胎龄31～33周早产儿低于胎龄34～36周早产儿和足月儿;出生体重<1500g新生儿低于1500～2500g和>2500g的新生儿,P均<0.05;不同性别之间SOS值差异无统计学意义(P>0.05);早产适于胎龄儿低于早产小于胎龄儿,P<0.001;母妊娠期高血压疾病组早产儿高于非妊娠期高血压疾病组,P<0.05。(2)SOS值与胎龄(r=0.347,P<0.001)、母妊娠期高血压疾病(r=0.215,P=0.016)、宫内发育迟缓(r=0.367,P<0.001)、血钙(r=0.259,P=0.004)和血镁(r=0.234,...     

骨定量超声技术评价早产儿骨量和早产儿骨发育的影响因素

目的探讨骨定量超声技术(QUS)在评价早产儿骨量中的应用以及影响早产儿骨发育的因素。方法对2008年5月至2009年11月本院新生儿病房收治、<7天的早产儿采用QUS、选择左小腿胫骨中1/3段内侧面测量声波传导速度(SOS),同时通过问卷调查的形式,对新生儿性别、胎龄、出生体重及母孕期钙营养状况、居住状况、有无疾病、不良嗜好等进行调查,分析各因素对早产儿骨发育的影响。结果体重≤1500g、1501～2000g和2001～2500g早产儿SOS值分别为(2501±70)m/s、(2624±89)m/s和(2768±211)m/s,体重越大,SOS值越高,差异有统计学意义(P均<0.05)。不同性别早产儿SOS值差异无统计学意义(P>0.05)。体重≤1500g的早产儿血钙(mmol/L)、血磷(mmol/L)和碱性磷酸酶(U/L)均低于2001～2500g的早产儿[血钙:(1.98±0.12)比(2.10±0.17),血磷:(1.53±0.21)比(1.92±0.28),碱性磷酸酶:(196±38)比(201±19),P均<0.05]。孕期每日摄入牛奶>200ml的母亲所生早产儿SOS值为(2788±95)m/s,不喝牛奶组孕母所生早产儿SOS值为(2659±121)m/s,差异有统计学意义(P<0.05)。结论早产儿出生体重越低,SOS值、血钙、血磷和碱性磷酸酶越低;孕期母亲每日摄入牛奶有利于早产儿骨骼发育;QUS可用于早产儿骨量的评价。     

新生儿脐血瘦素水平测定及相关因素分析

目的测定脐血瘦素(leptin)水平并分析其相关因素,以探讨瘦素在胎儿生长发育中的作用.方法采用放射免疫法测定80例新生儿脐血瘦素水平,其中早产儿16例,足月儿64例.足月儿又分为小于胎龄儿11例,适于胎龄儿31例,大于胎龄儿22例.结果早产儿瘦素水平明显低于足月儿(4.25±3.19ng/mlvs9.86±5.50ng/ml,P＜0.001),足月儿中适于胎龄儿瘦素水平(8.91±5.20ng/ml)显著高于小于胎龄儿(5.17±2.46ng/ml)而低于大于胎龄儿(13.56±4.67ng/ml);脐血瘦素与胎龄、出生体重、身长、Kaup指数、头围、胎盘重量、脐血胰岛素、血脂等呈正相关关系;多元逐步回归分析表明体重、性别、胎龄是脐血瘦素的主要相关因素.结论各组新生儿瘦素水平有显著差异,体重、性别、胎龄是其主要相关因素,故瘦素对胎儿生长发育起着重要作用,是胎儿宫内生长发育的重要调控因子.     

新生适于胎龄儿血清瘦素与骨声波传导速度的关系

目的探讨新生适于胎龄儿血清瘦素、骨声波传导速度(SOS)随胎龄的变化,以及瘦素与新生儿骨SOS的关系。方法共收集65例新生适于胎龄儿,根据胎龄分为早期早产儿组(胎龄31~34周,14例),晚期早产儿组(胎龄34~37周,13例),足月儿组(胎龄≥37周,38例)。所有研究对象均测量出生体质量、身长、小腿长度,采用Ponderal指数(PI)估测新生儿营养状态,采用weststrate公式(F%)估测新生儿体脂含量。生后7 d内采集静脉血测定血清瘦素水平,同时采用超声定量技术测量左侧胫骨SOS。结果三组新生儿胎龄、出生体质量、身长、小腿长度、F%、PI、血清瘦素与骨SOS的差异均有统计学意义(F=11.90~140.20,P均0.01);各变量均随胎龄增大而增大(P均0.05)。Pearson相关分析提示,除足月儿身长、PI外,三组新生儿的血清瘦素与其胎龄、出生体质量、身长、PI、F%呈显著正相关(r=0.36~0.78,P均0.05)。三组新生儿骨SOS分别与其瘦素、胎龄、出生体质量及小腿长度呈显著正相关(r=0.33~0.76,P均0.05)。进一步多元线性逐步回归分析发现,仅新生儿的胎龄(β=0.39,P=0.014)和出生体质量(β=0.44,P=0.006)对其骨SOS的影响具显著性。结论新生适于胎龄儿血清瘦素及骨SOS均与胎龄、出生体质量呈正相关,瘦素对骨SOS有影响,但不是其直接影响因素。     

超声心动图检测动脉导管未闭对极低出生体重儿左室舒张功能多普勒参数的影响

目的探讨动脉导管未闭(PDA)对极低出生体重儿左室舒张功能多普勒参数的影响.方法对21例极低出生体重儿于生后12～18 d行超声心动图检查,其中13例动脉导管仍开放者为观察组,8例动脉导管已关闭者为对照组,比较两组间二尖瓣血流频谱左室舒张功能参数.结果观察组心脏指数较对照组显著增高,分别为(4.8±0.6)L/(min·m2)和(4.1±0.6)L/(min·m2),P=0.030;观察组E峰峰值速度、A峰峰值速度分别为(62.2±9.3)cm/s和(59.6±7.8)cm/s较对照组分别为(51.4±10.7)cm/s和(40.3±4.6)cm/s显著增加(P=0.025,P=0.000);观察组E峰减速时间、左室等容舒张时间分别为(59.3±6.0)ms和(49.3±6.6)ms较对照组分别为(84.8±6.5)ms和(59.0±3.8)ms显著缩短(P=0.000,P=0.001);E、A峰峰值速度的比值较对照组显著减小(分别为1.05±0.14和1.27±0.21,P=0.009),但两组比值均＞1;舒张早期充盈分数无显著性差异.结论PDA导致左心室前负荷增加,使极低出生体重儿生后左室舒张功能成熟延迟,并可引起左房压的显著升高.     

新生儿出生后24小时内凝血功能检测的临床意义分析

目的探讨不同胎龄以及不同体重新生儿凝血功能指标的差异,为判断凝血功能指标的临床意义提供参考。方法2015年1月至2018年12月期间,在解放军总医院第五医学中心新生儿科住院治疗的新生儿中,纳入170例胎龄28~42周、出生8 h内入院的新生儿,其中男性87例,女性83例。按胎龄分为早期早产儿组、晚期早产儿组和足月儿组。按新生儿出生体重分为正常出生体重组、低出生体重组和极低出生体重组。按是否小于胎龄分为早产适于胎龄儿组、早产小于胎龄儿组、足月适于胎龄儿组、足月小于胎龄儿组。于生后24 h内抽取静脉血,检测活化部分凝血活酶时间(activatedpartial thromboplastin time,APTT)、凝血酶原时间(prothrombin time,PT)、纤维蛋白原(fibrinogen,FIB)、凝血酶时间(thrombin,TT)及D-二聚体(D-dimer)。结果早期早产儿组的APTT、PT、D-二聚体水平均高于晚期早产儿组及足月儿组(P值均<0.05),FIB水平低于晚期早产儿组及足月儿组(P值均<0.05);晚期早产儿组的APTT、PT水平均高于足月儿组(P值均<0.05),但两组间D-二聚体、FIB水平比较,差异无统计学意义(P值均>0.05)。极低出生体重组的APTT、PT、D-二聚体水平均高于低出生体重组及正常出生体重组(P值均<0.05),FIB水平低于低出生体重组及正常出生体重组(P值均<0.05);低出生体重组的APTT、PT水平均高于正常出生体重组(P值均<0.05),但两组间D-二聚体、FIB水平比较,差异无统计学意义(P值均>0.05)。早产小于胎龄儿组D-二聚体水平高于早产适于胎龄儿组(P<0.05),其余指标比较差异无统计学意义(P值均>0.05);足月适于胎龄儿与足月小于胎龄儿组的凝血指标比较,差异均无统计学意义(P值均>0.05)。早产儿出血发生率高于足月儿[26.6%(29/109)与8.2%(5/61),χ^2=9.019,P=0.003]。结论新生儿凝血指标有胎龄和体重差异,胎龄越小、体重越低的新生儿凝血功能越不完善。     

新生儿血清瘦素水平与生长发育关系研究

目的：探讨新生儿血清瘦素与生长发育的关系。方法：采用放射免疫法检测80例新生儿静脉血和脐血瘦素水平,其中66例足月儿分为大于胎龄儿(LGA)组18例,适于胎龄儿(AGA)组32例,小于胎龄儿(SGA)组16例。采用Rohrer’s指数=出生体重(g)×100/身长(cm)~3估测新生儿营养状态。结果：早产儿血清瘦素水平明显低于足月儿[(0.66±1.03)ng/ml vs(3.59±2.16)ng/ml],P<0.01;足月儿中AGA血清瘦素水平[(3.06±0.96)ng/ml]明显低于LGA[(4.03±2.22)ng/ml],而高于SGA[(1.13±1.98)ng/ml];足月新生儿血清瘦素水平与Rohrer’s指数、新生儿体重、胎龄呈显著正相关(r=0.61,0.68,0.62,P均<0.01)。结论：新生儿体内瘦素是反映新生儿的发育和营养状态的有用指标。[中国当代儿科杂志,2003,5(1):29-30]     

新生儿经皮呼吸

1851年,Gerlach首先证实了人的皮肤能不断地吸收氧气,排泄二氧化碳。对成人已作过大量的研究。估计呼吸的1～2％是经过皮肤的。但是,没有对新生儿经皮气体交换作过直接测定。作者应用皮肤细胞测量气体交换,对27例新生儿(出生体重0.96到4.43公斤,胎龄27到40周)分成三个胎龄组:37周到足月儿(12例),31到36周(8例),27到30周(7例),进行了经皮呼吸的研究。结果足月儿经皮气体交换速度比成人慢。在空气中,足月儿氧吸收及二氧化碳排泄平均为32.0±8.7、40.5±22.4ml/m~2/h,成人为62±9.4、86.5±12.8ml/m~2/h。在高浓度氧中,足月儿对氧的吸收速度也比成人慢。胎龄<31周的婴儿,在新生儿     

Bone measurements of infants in the first 3 months of life by quantitative ultrasound: the influence of gestational age, season, and postnatal age

Background: There are a few quantitative ultrasound (QUS) studies of bone status for Chinese children. Objective: To evaluate the clinical application and to investigate the bone status of neonates and young infants with QUS. Materials and methods: An ultrasound bone sonometer was used to measure the bone speed of sound (SOS) of the tibia in 542 neonates within 3 months of birth. Results: At birth, no significant difference of SOS was found between boys and girls, but there was a significant difference of SOS between premature infants and full-term infants. The SOS in neonates born during spring and summer was significantly lower than those born during autumn and winter. There were significant correlations between SOS and gestational age, and between bone SOS and birth weight in appropriate for gestational age (AGA) infants. Multiple regression analysis found that gestational age and infant birth season were two important factors influencing SOS. During the first 3 months, there was no significant difference in SOS between sexes. The SOS of infants showed an inverse correlation with postnatal age, and the decrease of bone SOS with age in premature infants was more marked than in full-term infants. Conclusions: QUS is suitable for evaluating bone status in infants with high precision. The study offers some basic data for neonates and young infants.     

Quantitative ultrasound measurements of bone speed of sound in premature infants

We measured bone speed of sound in premature infants by quantitative ultrasound. A total of 44 neonates participated in the study including 29 premature infants (median birth weight 1264 g, range 578-2420 g; median gestational age 31 weeks, range 24-36 weeks) and 15 full-term infants (median birth weight 3360 g, range 2700-3730 g; median gestational age 40 weeks, range 37-41 weeks). The left tibial speed of sound (SOS) was measured by quantitative ultrasound. Bone SOS was successfully measured in all infants. We found a significant correlation between tibial SOS and gestational age (r = 0.78, P < 0.0005), but a significant inverse correlation between tibial SOS and post-natal age (r = -0.78, P < 0.0005). Bone SOS was significantly (P < 0.05) higher in full-term infants (3101 m/s, range 2899-3314 m/s) compared to premature infants (2821 m/s, range 2516-3139 m/s), and compared to a subgroup of the premature infants who reached corrected age of full-term infants (2706 m/s, range 2516-2892 m/s, n = 13). Bone SOS was lower (2745 m/s, range 2533-3036 m/s, n = 16) in very low birth weight premature infants (birth weight < 1500 g). CONCLUSION: The results indicate that tibial speed of sound was reduced in premature infants (in particular very low birth weight) compared to full-term infants even when premature infants reached the corrected age of their full-term peers. The potential role of this technique in assessing osteopenia in premature infants warrants further exploration.     

Tissue carnitine reserves of newborn infants

This study assessed the tissue reserves of carnitine at birth in a group of neonates (n = 22) of varying gestational age dying within 24 h of birth, prior to possible changes in carnitine status induced by postnatal intervention. Tissue carnitine concentration was highest in the muscle in each infant. The mean (+/- SD) muscle carnitine concentration of 8.4 +/- 3.6 nmol/mg noncollagen protein (NCP) in very immature infants (less than or equal to 1000 g birth weight) was significantly lower than the corresponding mean (+/- SD) values of 14.0 +/- 3.2 nmol/mg NCP in larger preterm infants (1001-2500 g; P less than 0.01) and 19.4 +/- 2.6 nmol/mg NCP in term infants (greater than or equal to 2501 g; P less than 0.001). Muscle carnitine concentration correlated positively with gestational age (r = 0.832; P less than 0.001) and with body dimensions. Liver and heart carnitine concentrations did not correlate significantly with gestation or body dimensions. The mean (+/- SD) liver carnitine concentration for all the neonates as a group was 4.1 +/- 1.5 nmol/mg NCP. The mean (+/- SD) heart carnitine concentration was 4.7 +/- 1.3 nmol/mg NCP. In comparison to adult controls, tissue carnitine concentrations were markedly lower in neonates, particularly in immature newborns. These data suggest that newborn infants, especially premature babies, are born with limited tissue reserves of carnitine and are therefore at an increased risk for developing carnitine deficiency and its adverse effects in the postnatal period, particularly if maintained on carnitine-free intravenous nutrition for prolonged periods of time.     

Disproportionate alterations in body composition of large for gestational age neonates

OBJECTIVE: The objective was to compare dual-energy x-ray absorptiometry-measured body composition between large (LGA) and appropriate (AGA) birth weight for gestational age neonates.Study design: LGA term infants (n = 47) with birth weights > or =4000 g were compared with 47 gestational age-matched AGA infants; 11 LGA infants were born to mothers with gestational (9) or pregestational diabetes (2). Dual-energy x-ray absorptiometry scans were performed at 1.8 +/- 1.0 days after birth. RESULTS: Body weight and length were the dominant predictors of body composition in LGA and AGA neonates. However, LGA neonates had significantly (P <.001, all comparisons) higher absolute amounts of total body fat, lean body mass, and bone mineral content and had significantly (P <.001, all comparisons) higher proportions of total body fat and bone mineral content but lower lean body mass as a percent of body weight. The changes for total body fat and lean body mass as a percent of body weight were greatest (P <.001) in LGA infants whose mothers had impaired glucose tolerance. CONCLUSION: LGA neonates have higher body fat and lower lean body mass than AGA infants. Impaired maternal glucose tolerance exaggerated these body composition changes.     

Cord prealbumin values in newborn infants: effect of prenatal steroids, pulmonary maturity, and size for dates

We assessed cord prealbumin concentrations in 214 appropriate for gestational age newborn infants, 21 small for gestational age infants, and 27 large for gestational age infants to establish normal values and to assess the effect of intrauterine growth, prenatal steroids, and pulmonary maturity on prealbumin levels. Cord prealbumin values were significantly correlated with increasing gestational age (r = 0.33; P less than 0.001) and birth weight (r = 0.40, P less than 0.001) in the AGA neonates. Neonates born before 37 weeks gestation had significantly lower prealbumin levels than those born at term (P less than 0.001). The SGA infants had significantly lower levels than age-matched AGA controls (P less than 0.01), and LGA infants had significantly higher levels than age-matched AGA controls (P less than 0.001). In preterm infants, those with exposure to prenatal steroids (betamethasone or premature rupture of membranes) had significantly higher prealbumin values than control infants of comparable age and weight (P less than 0.001). Infants without respiratory distress syndrome had higher levels than those of comparable age and weight with hyaline membrane disease (P less than 0.05). This study demonstrates that a correlation of gestational age and birth weight exists with cord prealbumin levels, and that the large variability at each gestational age may be accounted for in part by appropriateness of size for dates, prenatal steroid exposure, and pulmonary maturity.     

Tibial speed of sound in term and preterm infants

The tibial speed of sound (SOS) was measured in 91 healthy singleton infants between 31 and 42 weeks of gestation and 12 sick preterm infants. In healthy infants, the tibial SOS was associated with corrected gestational age (r = 0.40, p < 0.001) but not birth weight. The median tibial SOS in 12 sick preterm infants (2,772, range 2,566-2,934 m/s), whose corrected gestational age was between 31 and 42 weeks, was lower (p < 0.001) than that of 69 healthy gestation-matched healthy infants (3,100, range 2,870-3,381 m/s). Tibial SOS measurements may allow radiation-free assessment of metabolic bone disease of prematurity.     

Longitudinal measurements of bone status in preterm infants

BACKGROUND: Quantitative ultrasound measurement of the speed of sound (SOS) through bone has been investigated as a means of assessing bone status in preterm infants. Few studies report longitudinal measurements. OBJECTIVE: To assess longitudinal changes in bone SOS in preterm infants. METHODS: Sixty preterm infants with gestational ages of < 33 weeks and with birth weight appropriate for gestational age (AGA), and 48 healthy, term AGA infants were enrolled. SOS measurements of the tibia were made within the first week of life in the preterm infants, and within the first 72 hours of life in the term infants. During their hospital stay, weekly measurements of tibial SOS were made in 29 of the preterm infants, who were divided into three gestational age groups: Group 1: 24-26 weeks (n = 8), Group 2: 27-29 weeks (n = 9), and Group 3: 30-32 weeks (n = 12). RESULTS: The median SOS value for the 60 newborn preterm infants was significantly lower than that for the 48 newborn term infants (2,924 versus 3,036 m/sec, p < 0.001). At each time point, SOS values for each of the preterm infant gestational age groups were significantly lower than the term newborn infant SOS values. SOS values decreased significantly over time for the entire cohort of 29 preterm infants (p < 0.001), and for Groups 1 (p = 0.015) and 2 (p = 0.003). At several time points, there was a significant negative correlation between serum alkaline phosphatase levels and SOS values, and a significant positive correlation between serum phosphorus levels and SOS values. CONCLUSION: SOS measurements of the tibia decline during hospitalization in preterm infants, suggesting a progressive loss of bone strength. Longitudinal measurements of bone SOS in combination with serum alkaline phosphatase and serum phosphorus levels may identify infants at risk of developing osteopenia of prematurity.     

早产儿生后早期血清降钙素原生理变化规律的研究

目的探讨生后不同时间和不同胎龄的早产儿血清降钙素原(PCT)生理变化规律。方法无感染新生儿217例,其中足月儿115例,早产儿102例,后者依据胎龄分为3个亚组:30～32周(30例)、33～34周(35例)、35～36周(37例),分别研究其生后0～12 h、13～24 h、25～36 h、37～48 h、49～72 h、73～96 h、97～120 h、121～144 h PCT水平变化规律。结果新生儿生后随着时间推移,PCT逐渐升高,24 h左右达高峰,其后逐渐下降,生后96 h左右降至儿童正常值。早产儿组PCT峰值晚于足月儿组,约在生后36 h出现,此后缓慢下降,96 h左右降至和足月儿数据相当。30～32周早产儿生后PCT数值维持低浓度水平,37～48 h逐渐升高,升高时间晚于33～34周及35～36周早产儿。结论新生儿在生后早期PCT有一个先增高后下降的动态变化过程,其中早产儿分泌高峰要迟于足月儿。32周以前早产儿生后36 h之内PCT水平较低。     

Breath hydrogen excretion in the premature neonate

We measured breath hydrogen excretion in 103 neonates from birth to as late as 2 months of age. The patients weighed less than 2000 g at birth and were part of a study of hydrogen excretion as a screening test for necrotizing enterocolitis. Hydrogen excretion in parts per million was normalized for the quality of the expired air by dividing by the Pco2 of the gas sample The rise in the H2/CO2 ratio was influenced by gestational age, energy intake, and antibiotic usage but not by the daily frequency of feeding. The mean +/- SD peak H2/CO2 ratio was 5.1 +/- 3.6 ppm per millimeter of mercury and occurred at 16.0 +/- 11.0 days of age. The age at which the peak H2/CO2 occurred varied with gestational age. Patients born between 23 and 28 weeks gestational age (n = 34) were 22.9 +/- 13.1 days of age when they experienced their peak H2/CO2 ratio, whereas those born between 29 and 34 weeks gestational age (n = 62) were 12.2 +/- 7.5 days of age. The age at which the peak H2/CO2 ratio occurred did not differ between these two groups when corrected for the age at which oral intake exceeded 420 kJ/kg per day. These results suggest that premature neonates require experience with ingesting more than 420 kJ/kg per day before bacteria and carbohydrates are present in large enough quantities to permit measurable hydrogen production. This information will be useful in future studies of premature gut development and physiology and in studying pathologic processes in which malabsorption may play a role.     

Measurements of bone turnover markers in premature infants

We determined the levels of circulating bone turnover markers in preterm infants during the first weeks of life. Twenty premature infants (mean gestational age 27+/-2.2 weeks, mean birth weight 894+/-231 g) hospitalized in the neonatal intensive care unit (NICU) at the Meir General Hospital, Israel, participated in the study. Measurements of bone turnover markers were performed at birth, and every week thereafter for an average follow-up of 11.2+/-0.7 weeks. Bone osteoblastic activity was assessed by measurements of circulating osteocalcin, bone-specific alkaline phosphatase (BSAP) and the C-terminal procollagen peptide (PICP) levels. Bone resorption was assessed by measurements of serum levels of the carboxy-terminal cross-links telopeptide of type I collagen (ICTP). All three markers of osteoblastic activity increased markedly and significantly during the first three weeks of life, and then continued to increase gradually until week 10 (p<0.01). Circulating ICTP levels increased in the first week of life and then decreased gradually throughout the follow-up (p<0.01). The study participants were divided into premature infants born at extremely low birth weight (ELBW: <1000 g, n=12) and very low birth weight (VLBW: 1000-1250 g, n=8). Osteocalcin (in weeks 2-5 of life), PICP (weeks 3-5), and ICTP levels (weeks 2-3) were significantly higher in VLBW preterms. These results suggest increased bone formation in premature infants in the first three months of life. The increased bone turnover in VLBW compared to ELBW premature infants may be the result of a generally higher morbidity in ELBW preterm infants in early stages of life.