Metabolic consequences of intrauterine growth retardation in very low birthweight infants

By the combination of energy and macronutrient balances, continuous open circuit computerized indirect calorimetry, and anthropometry, we have compared small for gestational age (SGA) and appropriate for gestational age (AGA) very low birthweight infants with respect to metabolizable energy intake (mean +/- SE: 125.9 +/- 2.5 versus 130.4 +/- 3.5 kcal/kg X day), energy expenditure (67.4 +/- 1.3 versus 62.6 +/- 0.9 kcal/kg X day), storage of energy and macronutrients and growth. Fourteen studies in six SGA infants (gestational age, 33.1 +/- 0.3 weeks; birthweight, 1120 +/- 30 g) and 22 studies in 13 AGA infants (gestational age, 29.3 +/- 0.4 weeks; birthweight, 1155 +/- 40 g) were performed. The SGA infants had a lower absorption of fat (68.7 +/- 3.2 versus 79.7 +/- 1.7%) and protein (69.1 +/- 3.2 versus 83.4 +/- 1.5%) and hence increased (P less than 0.001) energy loss in excreta (29.9 +/- 2.8 versus 18.2 +/- 1.5 kcal/kg X day). The significant hypermetabolism of SGA infants by 4.8 kcal/kg X day was associated with an increased fat oxidation. Despite lower energy storage, SGA infants were gaining weight (19.4 +/- 0.9 g/kg X day), length (1.25 +/- 0.14 cm/week), and head circumference (1.16 +/- 0.9 cm/week) at higher rates than the AGA group. The energy storage per g weight gain was lower (P less than 0.001) in the SGA group (3.0 +/- 0.14 versus 4.26 +/- 0.26 kcal) reflecting higher water, lower fat (22.2 +/- 1.8 versus 33.8 +/- 2.5%; P less than 0.001) and lower protein (7.7 +/- 0.5 versus 12.5 +/- 0.8%; P less than 0.001) contents of weight gain in the SGA group.     

Cerebral artery flow velocity acceleration and deceleration characteristics in newborn infants

To evaluate maturational differences in the cerebral artery blood flow velocity characteristics, we measured the middle cerebral (MCA) and basilar artery blood flow velocity and time intervals using a real-time imaging pulsed Doppler system in 39 preterm and 25 term infants. Preterm MCA and basilar artery mean Doppler spectral area under the curve were approximately 22 and 25% lower than the corresponding term values, with a significant increase during gestation as revealed by regression models. Paradoxically, the mean MCA systolic acceleration and deceleration slopes were approximately 28 and 18% higher in preterm than in term infants: acceleration 701.2 +/- 160 cm/s2 versus 546.4 +/- 156.5/s2 (p less than 0.005), and deceleration 222.2 +/- 71.6 cm/s2 versus 188.2 +/- 52.2 cm/s2 (p less than 0.05), respectively. Similarly, acceleration and deceleration pressure half times for MCA were about 15 and 18% shorter in the preterm (p less than 0.01 and less than 0.005). Multiple regression models controlling for velocity and frequency terms revealed an inverse relationship between gestational age and MCA acceleration (p less than 0.005), and a positive relationship between gestational age and MCA acceleration pressure half times (p less than 0.02). In preterm infants the MCA specific index of pulsatility was about 32% higher (p less than 0.05) than in the term, which was also inversely related to gestational age in a regression model controlling for velocity terms (p less than 0.02). However, the basilar artery acceleration and deceleration slopes were not significantly different between term and preterm groups, nor showed a significant gestational age effect in the multiple regression models.(ABSTRACT TRUNCATED AT 250 WORDS)     

Increased energy expenditure and fecal fat excretion do not impair weight gain in small-for-gestational-age preterm infants.

In order to optimize the nutrition of high-risk premature infants beyond the early postnatal period, a more precise knowledge of individual nutritional requirements is needed. We therefore studied the influence of intrauterine growth retardation on energy expenditure and nutrient utilization determined by indirect calorimetry and fecal fat excretion (steatocrit) in nineteen premature infants who were appropriate-for-gestational-age (AGA; mean gestational age 29.9+/-0.3 weeks, mean birth weight 1.30+/-0.05 kg) and thirteen small-for-gestational-age (SGA) premature infants [mean gestational age 32.4+/-0.5 weeks, mean birth weight 1.024+/-0.07 kg (i.e., below the 10th percentile)] during the first and second month of life. All infants were clinically stable during the study period. In nine SGA infants we observed a significantly higher steatocrit compared to twelve AGA infants (29+/-1 vs. 17+/-1% p = 0.0001). SGA infants (n = 12) also showed a slightly (albeit statistically not significantly) higher energy expenditure than AGA infants (n = 15) (58.7+/-1.9 vs. 53.6+/-1.5 kcal/kg per day, p = 0.054). Despite the increased fat excretion and higher energy expenditure, SGA infants gained weight more rapidly during the study period than AGA infants (20+/-1 vs. 17+/-1 g/kg per day, p = 0.026). We conclude that influences of intrauterine growth retardation on energy expenditure and nutrient utilization persist during the first weeks of extrauterine life. However, these metabolic changes do not impair the capability of SGA infants for extrauterine catch-up growth if adequate nutrition is provided.     

Association between serum leptin and anthropometric parameters at birth and at 15th day of life in infants born asymmetrically small for gestational age

The aim of this study was to investigate changes in skinfold measurements taken at three sites, mid-arm circumference and umbilical circumference during the first 15 days of life; and to evaluate relationships between anthropometric measurements and umbilical cord blood serum leptin levels in infants born small for gestational age (SGA) and appropriate for gestational age (AGA) infants. Of 50 newborn infants, 25 were SGA and 25 were AGA. Neonates' weight, mid-arm circumference (MAC), umbilical circumference (UC), and triceps, subscapular and periumbilical skinfold thicknesses were measured (Holtain callipers) immediately after delivery. Anthropometric parameters were measured again at 15th days of age. At birth, mean birth weight, mean skinfold thickness, MAC and UC measurements in the AGA group were significantly higher than those of the SGA group. These differences were also found on the 15th day. Birth weight correlated with all skinfold thicknesses, MAC and UC at birth. Weight at 15th day of life correlated with skinfold thicknesses, MAC and UC at 15th day of life. Cord blood leptin level was significantly lower in the SGA than in the AGA infants. This difference continued on the 15th day. When cord blood leptin level was compared with that of the 15th day, we found that leptin levels in the cord blood were significantly higher. There were significantly positive correlations between leptin levels and birth weight and skinfold thicknesses when the infants were all grouped together. When the newborns were grouped according to birth weight, there were positive correlations between cord blood serum leptin levels and these parameters in the AGA group, but no correlation in the SGA group. At the 15th day of life serum leptin levels correlated with weight, subscapular and triceps skinfold thickness in the AGA group, but only with triceps skinfold thickness in the SGA group.     

Term infants with fetal growth restriction are not at increased risk for low intelligence scores at age 17 years

OBJECTIVE: To assess the long-term cognitive outcome of small for gestational age (SGA) compared with appropriate for gestational age (AGA) infants. DESIGN: Data from the Jerusalem Perinatal Study was matched with information from the army draft medical board. SGA and severe SGA were defined as birth weight below the 10th and 3rd percentiles for gestational age, respectively. A multiple linear regression analysis was performed to control for clinical, perinatal, and socio-demographic confounding variables. SUBJECTS: A cohort of 13,454 consecutive singleton term infants born between 1974 and 1976. Main outcome measure: IQ at age 17 years. RESULTS: SGA infants had lower adjusted mean +/- SE IQ scores compared with their AGA peers: 102.2 +/- 0.9 versus 105.1 +/- 0.7 (P <.0001) for males and 102.5 +/- 0.9 versus 103.9 +/- 0.7 (P <.015) for females. SGA was not associated with lower academic achievements compared with AGA. CONCLUSION: After controlling for multiple confounders, being born SGA at term is associated with slightly lower intelligence test scores at age 17 years. However, the clinical significance of the small difference is not evident in academic achievements.     

Assessment of proportional growth of very low birth weight infants fed banked human milk

Twenty appropriate (mean +/- S.D., gestational age (AGA): 29.9 +/- 1.5 weeks) and 15 small (GA: 34.6 +/- 2.4 weeks) for gestational age (SGA) very low birth weight infants fed banked mature human milk were studied until term for anthropometric parameters: midarm (MAC), chest (CC), head (HC) circumferences, triceps (TSKF) and subscapular (SSKF) skinfold thickness recorded at 15 and 60 s, dynamic skinfold (delta % SKF), muscle (AMA) and fat (AFA) areas, weight and length. In AGA infants, all the parameters at term were significantly lower in extrauterine (EUL) that in intrauterine life (IUL). At term the relative proportion of AFA to total arm area was increased in EUL compared to IUL both in AGA (25.87 +/- 3.8 vs. 23.26 +/- 1.27% respectively, P less than 0.01) and in SGA infants (21.89 +/- 4.63 vs. 18.81 +/- 3.9 respectively, P less than 0.05). SGA infants showed a similar growth in EUL compared to IUL, and a significantly lower AMA and AFA than in AGA infants in EUL. Although HC was in both infants below the 10th centile at term, the ratio weight/HC2 suggests a relative preservation of head growth in EUL compared to IUL (AGA: 20.72 less than 0.87 vs. 22.65 +/- 1.46 respectively, P less than 0.001; SGA; 20.82 +/- 1.16 vs. 21.62 +/- 1.86 respectively, NS). Delta %SKF were negatively correlated with post-conceptional age suggesting a loss of extracellular water in AGA (delta %TSKF: r = -0.287, P less than 0.02) and in SGA infants (delta %TSKF: r = -0.301, P less than 0.02; delta %SSKF: r = -0.316, P less than 0.02). An intrauterine model of discrimination between AGA and SGA infants does not apply to EUL. An equation was established in SGA infants with the best discriminant parameters giving a predictive post-conceptional age: post-conceptual age (PCA) (weeks) = 0.276 HC (cm) + 0.723 CC (cm) - 0.122 MAC (cm) + 0.5 TSKF (mm) + 10.173, (r = 0.867, P less than 0.001) allowing a clear discrimination between AGA and SGA infants. These results suggest that infants show quite different growth patterns between IUL and EUL both for AGA and SGA infants.     

Cardiac hypertrophy and altered hemodynamic adaptation in growth-restricted preterm infants

The objective was to elucidate hemodynamic adaptation in very low birth weight (<1500 g) infants after intrauterine growth retardation. 31 growth-retarded (SGA, birth weight <-2 SD) and 32 appropriate for gestational age (AGA, birth weight within +/- 1 SD range) infants were enrolled. In SGA infants, the diastolic diameters of the interventricular septum and the left ventricle were increased, and serum brain natriuretic peptide (BNP) was elevated. Left ventricular output (LVO) of the AGA infants increased from 150 +/- 28 to 283 +/- 82 mL/kg/min during the study (p < 0.01). The SGA infants had a higher initial LVO than the AGA infants (243 +/- 47 versus 150 +/- 28 mL/kg/min, p < 0.05), but did not show further LVO increase during the study period. Red cell (RCV) and blood (BV) volume were assessed by Hb subtype analysis, when packed donor red cells were transfused. RCV and BV did not differ between the groups initially, but RCV increased by 18% and BV by 29% in the AGA group during the first 3 d. On day 3, AGA infants had larger BV than the SGA infants (88 +/- 5 versus 73 +/- 12 mL/kg, p < 0.05). In conclusion, cardiac hypertrophy, elevated initial LVO and BNP of the SGA infants suggest increased cardiac workload after intrauterine growth retardation. Based on the BV and RCV data, blood volume regulation may also be impaired. The data suggest that SGA preterm infants may be exposed to an increased risk of circulatory failure during early adaptation.     

34 周以下适于胎龄及小于胎龄早产儿出生 2 周内 蛋白质、能量摄入及体质量变化

目的了解34周以下早产适于胎龄儿(AGA)和小于胎龄儿(SGA)生后蛋白质、能量摄入量以及体质量z评分的变化情况。方法回顾收集2012年1月至2014年12月入院的314例早产儿,比较268例AGA和46例SGA早产儿生后2周内蛋白质、能量摄入情况和体质量变化。结果 SGA组住院时间、肠外联合肠内营养时间、全肠内营养时间、达足量喂养时间均较AGA早产儿长,差异有统计学意义(P??0.05);SGA组生后第4、8、12天能量摄入量明显低于AGA组,SGA组生后第6、8天总蛋白质摄入量明显低于AGA组,差异均有统计学意义(P??0.05);SGA组日平均体质量增长量大于AGA组,差异有统计学意义(P??0.05);AGA组与SGA组生后2周内体质量z评分均逐渐远离中位水平,且SGA组2周时体质量z评分低于AGA组(P??0.05)。结论胎龄??34周的SGA早产儿恢复出生体质量后的生长速率快于AGA早产儿,存在一定的追赶生长;但SGA、AGA早产儿的生长均有待提高。     

Intrauterine growth restriction and postnatal steroid treatment effects on insulin sensitivity in preterm neonates

OBJECTIVES: To study whether intrauterine growth restriction (IUGR) is associated with decreased sensitivity to the main fetal growth factor, insulin, and the effect of glucocorticoid therapy on insulin sensitivity in preterm infants. STUDY DESIGN: Newborn infants with a birth weight (BW) of< 1500 g were classified as appropriate for gestational age ([AGA], BW within +/- 1 SD, n = 10), or small for gestational age ([SGA], BW <-2 SD, n = 13); 5 AGA infants and 8 SGA infants received systemic steroids. An abbreviated modified minimal model test was performed, consisting of sequential blood samples for glucose and insulin assays, and intravenous infusions of 0.3 g/kg glucose and 0.02 U/kg regular human insulin. The insulin sensitivity index (S(I)) was calculated using a computer program. RESULTS: The basal insulin/glucose ratio (I/G) and S(I) did not differ between the AGA and SGA groups. Steroids did not influence the I/G nor the S(I) of AGA infants (10.2 +/- 6.7 vs 8.2 +/- 2.3), but decreased the S(I) in the SGA group (12.2 +/- 5.1 vs 5.3 +/- 2.7, P <.05). CONCLUSIONS: Insulin sensitivity of neonates can be measured by the modified minimal model. IUGR is not associated with impaired fetal glucose tolerance. Early neonatal steroid treatment decreases insulin sensitivity in SGA infants, which may contribute to their risk of having hyperglycemia.     

Peripheral nerve conduction velocity and brainstem auditory evoked responses in small for gestational age preterm infants

Ulnar nerve conduction velocity (NCV) and brainstem auditory evoked responses (BAER) were measured in each of 11 preterm small for gestational age (SGA) infants born at less than 35 weeks gestation. The mean motor NCV in the SGA infants was similar to that reported for infants who were appropriately grown for their gestational age (AGA). However, the mean central conduction time of the BAER in SGA infants was significantly shorter than that of AGA infants of the same post-menstrual age. Thus, the precocious development of auditory brainstem neural function in preterm SGA infants is not accompanied by changes in functional maturation of the peripheral motor nerves.     

Serum ferritin, iron levels and iron binding capacity in asymmetric SGA babies.

The concentration of serum ferritin reflects the extent of iron stores in premature infants. We aimed to determine serum ferritin levels and iron status in asymmetric small for gestational age (SGA) babies. This study was performed on 21 SGA babies and 19 appropriate for gestational age (AGA) babies. Hemoglobin, iron, iron binding capacity and ferritin levels were investigated in the first six hours after the birth. Hemoglobin levels in the SGA and control groups were 20.9 +/- 1.3 (19.4-23.4 g/dl) and 19.6 +/- 0.8 (18.5-21.5 g/dl), respectively (p = 0.001). Serum ferritin levels in the SGA and AGA groups were 58.36 +/- 20.1 ng/ml and 90.46 +/- 30.5 ng/ml, respectively. Ferritin levels were found lower in the SGA group (p < 0.001). In the SGA group, decreased serum iron and increased iron binding capacity were found but the difference was not significant (p > 0.05). Decreased ferritin levels may result from either impaired iron transport associated with uteroplacental vascular insufficiency or increased iron utilization during enhanced erythropoiesis in conditions characterized by chronic fetal hypoxia. Our results stress the significance of iron supplementation and careful anemia follow-up in term SGA babies. Because anemia progress early, beginning iron therapy as soon as possible is a necessity in SGA babies as in prematures.     

Growth and mineral metabolism in very low birth weight infants. I. Comparison of the effects of two modes of NaHCO3 treatment of late metabolic acidosis.

Twenty-six infants weighing less than 1,300 g at birth were divided into pairs according to birth weight (900-1,100 and 1,101-1,300 g) and gestational age ("appropriate" (AGA) = mean 31 weeks; and "small" (SGA) = mean 34 weeks). One member of the pairs was then allocated randomly to one of two treatment regimens with oral sodium bicarbonate. Group A was treated whenever base excess was greater than -8mEq/liter as detected on twice weekly testing and/or when suspected to be acidotic from failure to gain weight. In group B, base excess was maintained within 1 SD of normal (-3.2 +/- 1.7 mEq/liter). The infants received Enfalac 200 ml/kg/24 hr, at 67 cal/100 ml, with vitamin D 400 IU/24 hr added from age 2 weeks. The following measurements were made: daily weight, weekly length, skinfold thickness, head circumference, twice weekly blood pH, PaCO2, base excess, and weekly plasma total calcium, ionic calcium, total magnesium, inorganic phosphorus, and total protein. There were six pairs of each of AGA and SGA infants and two unpaired group A infants. Weekly weight gains did not differ between group A and group B or between AGA and SGA. Length increment was greater in AGA than in SGA babies (0.94 +/- 0.02 vs 0.85 +/- 0.04 cm/week) but not significantly so (P less than 0.1), and in group B babies compared to group A babies (0.973 +/- 0.029 vs 0.83 +/- 0.037 cm/week) (P less than 0.01). Plasma pH was lower in group A (7.23 +/- 0.02) than in group B (7.30 +/- 0.02) and calcium ion activity higher (group A 2.72 +/- 0.04; group B 2.51 +/- 0.06 mEq/liter) between ages 20 and 29 days. Plasma magnesium was higher in group A (1.77 +/- 0.04 mEq/liter) than in group B (1.56 +/- 0.06 mEq/liter) from age 20 to 39 days. Inorganic phosphorus concentrations were consistently higher in group A than in group B, but the differences did not reach significance. Mean total protein concentrations did not rise above 4.5 g/100 ml and tended to be higher in babies of group A than of group B. Bone age was retarded in all babies. Radiographs available for 7 of 13 SGA infants were normal, whereas 6 of 11 radiographs of AGA babies showed some osteoporotic changes.     

小于胎龄儿青春前期女孩硫化脱氢表雄酮和胰岛素水平的研究

目的探讨小于胎龄儿(SGA)青春前期女孩肾上腺机能初现及是否具有肾上腺机能早现、高肾上腺雄激素血症、高胰岛素血症和胰岛素抵抗现象。方法以符合纳入标准的SGA 39例为研究对象,年龄(7.4±1.7)岁,42例适于胎龄儿(AGA)为对照组,年龄(7.4±1.7)岁。在隔夜空腹12 h后,行身体检查,并抽血检测空腹血糖、胰岛素、硫化脱氢表雄酮(DHEAS)、皮质醇和雌二醇。胰岛素敏感性用空腹血糖与胰岛素乘积的倒数再取自然对数来评价。结果两组中未发现肾上腺机能早现的临床表现,两组间孕母孕龄、年龄、体重指数、空腹血糖、皮质醇、雌二醇和胰岛素敏感性指数差异无统计学意义。SGA组出生体重、研究时的身高和体重均低于AGA组,SGA血清胰岛素和DHEAS水平均高于AGA组(对数转换值:1.076±0.041vs.1.050±0.051,P<0.05;2.637±0.271vs.2.514±0.250,P<0.05)。AGA组DHEAS值在7岁以后出现明显增加,SGA组DHEAS值出现增加的趋势与AGA组比较有所提前。结论AGA女孩肾上腺机能初现的年龄约为7岁,而SGA女孩肾上腺机能初现有始动提前的趋势,青春前期SGA女孩有高肾上腺雄激素血症和胰岛素水平升高的现象,但以胰岛素敏感性指数来评价,尚未发现胰岛素抵抗现象。     

Neonatal coagulopathy in preterm,small-for-gestational-age infants

Our aim was to determine if antenatal hypoxia was associated with liver dysfunction and coagulation abnormalities in small-for-gestational-age (SGA) infants. Sixteen SGA infants, median gestational age 30 (range 26-32) weeks, who consecutively had had umbilical artery Doppler studies in the week before delivery, were compared to appropriate-for-gestational-age (AGA) controls, who were each matched to an SGA infant for gestational age. The median international normalised ratio (INR) was significantly higher (1.9 vs. 1.3, p < 0.001) and the neutrophil (p = 0.003) and platelet counts (p < 0.001), alkaline phosphatase (p < 0.001) and albumin (p < 0.02) levels significantly lower in the SGA compared to the AGA group. The umbilical artery pulsatility index (PI) was elevated, indicating antenatal hypoxia, in all but 1 of the SGA infants. Multiple linear regression analysis demonstrated that the INR was significantly related to the umbilical artery PI independent of the other variables (p = 0.0002, R(2) = 0.71). These results suggest that the coagulopathy seen in preterm SGA infants might at least be partially explained by antenatal hypoxia affecting the liver and hence vitamin K-dependent coagulation.     

Regional cerebral blood flow velocity patterns in newborn infants

Using range-gated pulsed Doppler sonography, cerebral blood flow velocity (CBFV) waveforms from the anterior cerebral artery (ACA), middle cerebral artery (MCA) and circle of Willis artery (CW) were examined in a total of 34 newborn infants. We compared the pulsatility index (PI) from the three cerebral arteries sampled in 10 term and 10 preterm (29 +/- 2 weeks) newborn infants without a history of perinatal asphyxia or intracranial pathology. The Pl in the ACA ranged from 0.60 to 1.03. There were no significant differences in Pl between the three vessels by paired comparisons. The Pl of the MCA differed from that of the ACA by 0.00 +/- 0.05. The variation coefficient (CV) was 7%. For CW with ACA, the difference was 0.00 +/- 0.04 and CV was 6%. Both intra- and interexaminer variation in Pl measurements were studied in another 14 infants. The variation coefficients were 5-8% for all three cerebral arteries. We showed that CBFV waveform patterns were similar in regional cerebral arteries, with Pl being a consistent CBFV index. In normal cerebral circulation, the intervessel Pl differences were within observer variations. Deviation from this may suggest abnormal regional cerebral haemodynamics.     

The influence of gestational age, size for dates, and prenatal steroids on cord transferrin levels in newborn infants

Serum transferrin levels assess protein status in older children and adults. To generate standards for its use in newborn infants, we measured umbilical cord serum transferrin levels in 161 appropriate (AGA), 25 large (LGA) and 16 small (SGA) for gestational age infants between 25 and 43 weeks' gestation. We also assessed the effects of intrauterine growth, exposure to prenatal steroids, and presence of pulmonary maturity on neonatal transferrin levels. Cord transferrin levels in AGA infants were significantly correlated with increasing gestational age (r = 0.60; p less than 0.001). Infants born before 37 weeks' gestation had significantly lower transferrin levels, when compared with those born at term (p less than 0.001). LGA infants had significantly higher levels than age-matched AGA infants (253 +/- 75 vs. 214 +/- 53 mg/dl; p less than 0.025). Despite significantly lower mean birth weights (p less than 0.001), SGA infants also had significantly higher levels than gestational age-matched AGA controls (227 +/- 63 vs. 167 +/- 40 mg/dl; p less than 0.005). For infants less than 35 weeks' gestation, neither the 20 preterm infants with exposure to prenatal steroids (maternal betamethasone), nor the 26 infants with pulmonary maturity had significantly elevated transferrin levels, when compared with gestational age-matched control infants. Newborn transferrin levels correlate well with gestational age and are significantly affected by size for dates, but not by a brief course of prenatal steroids or by pulmonary maturity.     

Glycerol metabolism and triglyceride-fatty acid cycling in the human newborn: effect of maternal diabetes and intrauterine growth retardation.

Kinetics of glycerol metabolism and triglyceride/fatty acid cycling were quantified in 12 healthy, normal, appropriate-for-gestational-age (AGA) infants, eight small-for-gestational-age (SGA) infants, and five infants of insulin-dependent diabetic mothers (IDM) at less than 48 h of age. Stable isotope-labeled [2-13C]glycerol and [6,6-2H2]glucose in combination with indirect respiratory calorimetry were used. The tracers were used as constant rate infusion and steady state isotopic enrichment of glucose, glycerol, and bicarbonate was measured by mass spectrometric methods. After a 7- to 9-h fast, the plasma glucose, glycerol, and FFA concentrations were similar in the AGA and IDM groups. In the SGA group, the plasma glucose concentration was significantly lower than that in the AGA group throughout the study, but plasma FFA and glycerol concentrations were not different from those in the AGA infants. Plasma betahydroxybutyrate concentration was significantly elevated in the AGA group compared with IDM and SGA infants (AGA 0.59 +/- 0.39, SGA 0.35 +/- 0.09, IDM 0.33 +/- 0.21 mmol/L; mean +/- SD). The rate of appearance of glycerol was significantly elevated (p less than 0.05) in SGA infants (AGA 9.47 +/- 2.11, IDM 9.55 +/- 2.14, SGA 12.15 +/- 3.87 mumol/kg.min). Between 80 and 90% of glycerol turnover was converted to glucose, accounting for 20% of glucose turnover with no significant difference in the three groups. Approximately 35% of glycerol carbon was recovered in the bicarbonate (CO2) pool. Less than 5% of CO2 carbon was derived from glycerol. Estimation of triglyceride-fatty acid cycle revealed that the triglyceride energy mobilized was increased in SGA infants.(ABSTRACT TRUNCATED AT 250 WORDS)     

Glucose production and oxidation in preterm infants during total parenteral nutrition

During total parenteral nutrition in preterm infants, glucose may be infused at high rates, but it is not known if the endogenous glucose production is fully suppressed under these circumstances. Eight preterm appropriate for gestational age (AGA) (birth wt: 1613 +/- 151 g, gestational age: 31.1 +/- 1.5 wk) and eight preterm small for gestational age (SGA) newborn infants (1185 +/- 241 g, 32.9 +/- 2.6 wk) receiving a glucose infusion rate of 7.55 +/- 0.56 and 8.16 +/- 0.65 mg/kg.min, respectively, were studied during continuous total parenteral nutrition at postnatal d 8. Glucose oxidation rate was determined with a primed constant infusion of [U-13C] glucose, measuring the 13CO2 production in breath gas by isotope ratio mass spectrometry and the glucose production rate in plasma by gas chromatography mass spectrometry. In breath gas of AGA and SGA infants, 60 and 65%, respectively, of the infused tracer appeared as 13CO2. The glucose production rates were 7.97 +/- 1.61 and 8.12 +/- 1.84 mg/kg.min in AGA and SGA infants, respectively, indicating that no significant endogenous glucose production occurred. The glucose oxidation calculated from the glucose production and 13CO2 production was 4.74 +/- 0.99 mg/kg.min in AGA infants and was significantly different from the carbohydrate oxidation rate of 6.62 +/- 1.23 mg/kg.min measured by simultaneous indirect calorimetry. In SGA infants, however, the glucose and carbohydrate oxidation rates were not significantly different at 5.33 +/- 1.56 and 6.16 +/- 2.45 mg/kg.min. It is concluded that 1-wk-old AGA or SGA preterm infants receiving total parenteral nutrition of 80 kcal/kg.d produce no endogenous glucose and their glucose oxidation rates are similar at 63-65% of the glucose infused. It is suggested that the significant difference between glucose and carbohydrate oxidation rates observed in AGA but not in SGA infants is due either to a higher rate of lipogenesis from carbohydrates, or, less likely, to a higher rate of glycogen oxidation.     

早产小于胎龄儿生长代谢的临床研究

目的 探讨早产小于胎龄儿（SGA）与适于胎龄儿（AGA）在住院期间生长代谢的差异,为临床对早产SGA进行营养干预提供依据。方法 1 370例早产儿纳入研究,根据胎龄与出生体重的关系分为SGA组（675例）与AGA组（695例）,比较两组早产儿住院期间的一般情况、体格增长及血生化指标等情况。结果 SGA组住院天数长于AGA组（P < 0.05）。与AGA组相比,SGA组出院体重、出院体重Z评分及出院身长均较低,宫外生长迟缓发生率较高（P < 0.05）,头围增长速率大于AGA组。与AGA组相比,SGA组达全肠内喂养时间及需肠外营养时间均较长（P < 0.05）。SGA组入院时白蛋白、前白蛋白、血清磷、出院前总胆汁酸高于AGA组,白蛋白低于AGA组（P < 0.05）。SGA组窒息、新生儿呼吸窘迫综合征、心肌损伤、喂养不耐受、肺炎、败血症、低血糖、低甲状腺素血症的发生率高于AGA组（P < 0.05）。结论 早产SGA住院期间体格发育明显落后于AGA,宫外生长迟缓发生率较高,更易出现并发症。     

Serum adiponectin concentrations in newborn infants in early postnatal life

Serum adiponectin levels were investigated in 28 small-for-gestational-age (SGA) and 34 appropriate-for-gestational-age (AGA) term neonates to examine how fetal growth correlates with adiponectin levels. A blood sample for determination of adiponectin was obtained during the first 24 h of life. The levels of serum adiponectin were significantly higher in all newborn infants than in healthy children (28.7 +/- 17.0 versus 9.3 +/- 6.1 microg/mL; p < 0.01). There was a significant difference in adiponectin levels between SGA and AGA infants (23.2 +/- 14.8 versus 33.2 +/- 17.5 microg/mL; p=0.02). For all of the newborn groups, serum adiponectin levels correlated positively with birth weight (r=0.27, p <0.05) and head circumference (r=0.30, p <0.05). There was no relationship between serum adiponectin levels and gestational age, birth length, blood glucose levels, or blood sampling time after birth. There was no gender difference in adiponectin levels in the entire newborn group (30.0 +/- 19.7 versus 28.0 +/- 15.5 microg/mL, in male and female infants). Our results suggest that hyperadiponectinemia and a positive relationship between the serum levels of adiponectin and birth weight in newborns cannot be explained by the low percentage of body fat alone. Lower adiponectin levels in SGA infants than in AGA infants are unlikely to suggest insulin resistance in intrauterine growth-retarded infants in early postnatal life but may be a predisposing factor in the future development of insulin resistance or type 2 diabetes.