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.     

Longitudinal investigation of the relationship between breast milk leptin levels and growth in breast-fed infants

BACKGROUND: It has been shown that leptin is present in breast milk and human mammary epithelial cells are able to synthesize leptin. It has been suggested that leptin in human milk might be involved in the regulation of postnatal nutrition and growth. AIMS: To investigate whether there is a relationship between leptin levels in human milk and weight gain in the postnatal period and to compare variations of milk-borne maternal leptin concentrations for small for gestational age (SGA), large for gestational age (LGA) and appropriate for gestational age (AGA) infants. INFANTS AND METHODS: Forty-seven healthy lactating women aged from 17-38 years and their infants were included in the study. The infants were separated into three groups according to birth weight as SGA (n = 11), LGA (n = 14) and AGA (n = 22). All infants were fed with breast milk during the study period. Anthropometric measurements were performed on the 15th day of life and at 1, 2, and 3 months of age, and the body mass index (BMI) of the infants' mothers was calculated. Breast milk leptin levels were analyzed by radioimmunoassay. RESULTS: Breast milk leptin levels were found reduced in the SGA group and increased in the LGA group compared to the AGA group at 15 days of life (13.4 +/- 2.2, 28.5 +/- 4.4 and 18.4 +/- 2 ng/ml, respectively; p <0.05). At 1 month of age, leptin levels in breast milk were significantly lower in the LGA group than in the AGA group (15.5 +/- 4.9, 19.4 +/- 1.7 ng/ml, respectively; p<0.05). There was no difference among the three groups at 2 and 3 months of age (p>0.05). There was a positive correlation between birth Weight and breast milk leptin levels on the 15th day (r = 0.47, p = 0.001). A negative correlation was found between weight gain during the first 15 days and 1 month of life and breast milk leptin levels on the 15th day (r = -0.44, p = 0.002; r = -0.40, p = 0.005, respectively). No relationship could be determined between breast milk leptin levels and BMI of the mothers. CONCLUSION: Maternal milk of SGA, LGA and AGA infants had different leptin levels, especially during the first month of life. More rapid growth was shown in the SGA infants during the first postnatal 15 days compared to AGA and LGA infants, and human milk leptin levels were significantly reduced in the SGA group. However, LGA infants gained more weight during the second 15 days of life and breast milk leptin levels were dramatically decreased in LGA and increased in SGA infants at the end of first month of life. These findings suggest that the presence of leptin in breast milk might have a significant role in growth, appetite and regulation of nutrition in infancy, especially during the early lactation period, and the production of leptin in breast tissue by human mammary epithelial cells might be regulated physiologically according to necessity and state of the infant.     

Whole blood fatty acid composition differs in term versus mildly preterm infants: small versus matched appropriate for gestational age

To investigate the associations between whole blood fatty acid (FA) profile and restricted intrauterine growth, any small for gestational age (SGA) infant born in our maternity ward through 1 y was matched with two appropriate for gestational age (AGA), of the same GA +/- 0.5 wk, infants, further subdivided into term and preterm. Whole blood was collected at d 4 on a strip and FA % composition assessed by means of gas chromatography. The whole sample consisted of 28 SGA versus 56 AGA born at term and 20 SGA versus 40 AGA born preterm at around 35 wks. Parent FA of the n-6 and n-3 FA families were higher in preterm groups, whereas docosahexaenoic acid was higher in term AGA (median % values, 3.9 versus 3.7 in term SGA, 2.8 in preterm AGA, and 2.5 in preterm SGA, p < 0.001). Term AGA had markedly higher values for the docosahexaenoic acid/alpha-linolenic acid ratio (median value: 91, versus 18 in term SGA, 12 in preterm AGA, and 10 in preterm SGA, p < 0.001). Term SGA had significantly lower levels of total monounsaturated FA and higher levels of eicosapentaenoic acid. Therefore, the 4-d whole blood FA pattern is associated with both GA and birth weight.     

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.     

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.     

Variation in size at birth in infants born small for gestational age in Lithuania

The aim of this study was to describe the heterogeneity in body proportions of infants born small for gestational age (SGA), defined by birthweight, and to study the relationship of placental size with neonatal anthropometric measurements. Anthropometry was evaluated in 107 symmetrically and asymmetrically growth-retarded infants born SGA (birthweight <-2 SD) and compared with 181 appropriate-for-gestational age infants (AGA; birthweight and length +/- 2 SD). Study children were born at Kaunas University Hospital during the period from 1 January 1998 to 25 August 2000. Two-thirds of SGA children were light (SGA(W)) and one-third was both light and short (SGA(WL)) for gestational age. Infants in both SGA groups were significantly leaner than AGA children. SGA(WL) infants had significantly larger heads in relation to their length compared with SGA(W) and even AGA children, probably indicating a brain-sparing effect. SGA(WL) children had the lowest mean placental weight, but the highest placental weight to birthweight (PW/BW) ratio. The PW/BW ratio was inversely correlated with most infant measurements; the strongest negative relationship was observed with birthlength and lower leg length. CONCLUSION: There is heterogeneity in children born SGA, defined by birthweight. It is suggested that the two SGA groups represent the continuum of intrauterine growth retardation, with an initial reduction in trophic growth and a subsequent retardation of linear growth. The PW/BW ratio is a strong indicator for impaired prenatal linear growth.     

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.     

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.     

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.     

Immunoglobulins IgG, IgM and IgA levels in preterm and small for date newborns.

Forty preterm [14 small for gestational age (SGA), 26 average for gestational age (AGA)] and 40 term (10 SGA and 30 AGA) babies were tested for immunoglobulins (Ig), G, M and A levels. IgG levels increased with gestational age from 922.00 +/- 14.00 mg/dl at 34 weeks to 1827.33 +/- 184.09 mg/dl at 40 weeks. Mean immunoglobulins were lower in SGA babies. IgG was 1029.59 +/- 122.80 mg/dl in SGA preterm babies and increased to 1262.00 +/- 200.0 mg/dl in 2 kg babies. IgM and IgA although increased with higher birth weight but rise was not statistically significant. More care to avoid infections in preterm and SGA babies, with lower immunoglobulin levels and less resistance, is recommended.     

Postnatal dependence of plasma copper and zinc levels on gestational age and maturity observed in infants fed a high zinc content formula

We studied the effect of gestational age and maturity on plasma zinc and copper levels at 10 and 120 days of age. The association of plasma zinc changes and body growth was also investigated. Infants were receiving a controlled intake of zinc and copper solely through a zinc-supplemented formula (4.7 mg/L of zinc and 0.16 mg/L of copper). Twenty-eight low-birthweight infants (less than 2,500 g) having gestational ages ranging from 33 to 40 weeks [17 with an appropriate birthweight for gestational age (AGA) and 11 small for gestational age (SGA)] were enrolled in the present study. Measurements of plasma zinc and copper concentration, weight, length, head circumference, and tricipital and subscapular skinfolds were carried out at 10 and 120 days of age. Proton-induced x-ray fluorescence technique (PIXE) was used to assess copper and zinc concentrations. At 10 days of age a significant correlation between copper concentration and gestational age was found. At 120 days of age the copper concentration was higher than at 10 days and independent of gestational age and maturity (mean +/- SEM = 116 +/- 5 micrograms/dl). At 10 days of age no significant correlation between zinc content and gestational age was found (86 +/- 4 micrograms/dl). The plasma zinc percent change over the period from 10 to 120 days of age was positively correlated with gestational age in the whole sample as well as in AGA and SGA infants separately.(ABSTRACT TRUNCATED AT 250 WORDS)     

Normal thyroid function in young adults who were born very preterm

There is some evidence for elevated thyrotropin (TSH) levels in children born preterm, but follow-up studies into adulthood are lacking. We tested whether thyroid function in young adults born at a gestational age < 32 weeks, with either an appropriate (appropriate for gestational age, AGA) or low birth weight for gestational age (small for gestational age, SGA), differed from that in age-matched controls. We made our measurements when the study participants reached 21 years of age. Serum concentrations of TSH and free T4 (fT4) and body composition were measured in subjects born preterm and AGA (n = 29) or SGA (n = 28), and in non-preterm controls (n = 30). The TSH and fT4 concentrations of participants were within normal limits. Free T4 levels in subjects born preterm were slightly higher than those in controls: 17.0 +/- 2.4 (AGA) and 17.2 +/- 1.7 (SGA) vs. 16.1 +/- 1.9 pmo/L (p = 0.04). TSH concentrations did not differ between groups. From these preliminary data, we conclude that young adults born preterm have a normal thyroid function.     

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.     

The effect of antenatal betamethasone on cord blood concentrations of retinol-binding protein, transthyretin, transferrin, retinol, and vitamin E

We assessed the effect of short-term (less than or equal to 1 week) and prolonged (greater than 1 week) exposure to antenatal betamethasone on umbilical cord serum concentrations of retinol-binding protein (serum t 1/2 = 12 h), transthyretin (t 1/2 = 2 days), transferrin (t 1/2 = 8 days), retinol (vitamin A), and vitamin E in appropriate-for-gestational-age preterm newborn infants of less than 36 weeks' gestation. A group of 30 infants whose mothers received a single course of betamethasone less than or equal to 1 week prior to delivery had significantly elevated mean retinol-binding protein and transthyretin but not transferrin concentrations when compared with a group of 30 gestational age- and birth weight-matched infants with no exposure to antenatal betamethasone. A group of eight infants whose mothers received multiple (more than two) weekly courses of betamethasone prior to delivery had significantly elevated mean serum concentrations of all three proteins when compared with eight gestational age- and weight-matched control infants with no betamethasone exposure. Serum retinol and vitamin E concentrations were measured in a group of 21 infants exposed to short-term prenatal betamethasone and were significantly greater than in a group of 21 control infants without steroid exposure. We conclude that antenatal steroids increase the umbilical cord serum concentrations of retinol-binding protein, transthyretin, transferrin, retinol, and vitamin E. The effect on the various serum proteins is dependent on the duration of exposure to steroids.     

Cord serum lipid and lipoprotein-cholesterol values in normal and betamethasone-treated newborns of varying gestational age.

Cord serum total cholesterol, very low density lipoprotein-, low density lipoprotein-, high density lipoprotein-cholesterol and triglyceride was determined in 30 AGA infants and 35 SGA infants born between the larger than or equal to 37th less than or equal to 42th week of gestation and in 26 AGA infants born between the larger than or equal to 33th less than 37th week of gestation. In SGA infants significantly higher VLDL-cholesterol and triglyceride values were found than in AGA infants. In AGA infants less than 37 weeks of gestation total cholesterol, LDL-, and HDL-cholesterol concentrations were higher than in AGA infants larger than or equal to 37 weeks of gestation. In 10 betamethasone-treated AGA infants less than 37 weeks of gestation HDL-cholesterol was higher than in 16 untreated AGA infants less than 37 weeks of gestation.     

Effect of gestational age upon prealbumin and retinol binding protein in preterm and term infants

The relationships between maternal and umbilical cord levels of prealbumin and retinol binding protein (RBP) were studied in 68 mothers and in their appropriate-for-gestational-age neonates delivered between 25 and 42 weeks gestation. Arterial and venous concentrations of prealbumin and RBP in cord sera were also studied in a subsample of eight infants. In cord sera, prealbumin and RBP levels increased with gestational age (prealbumin, r = 0.47; RBP, r = 0.40, p less than 0.01), and were significantly different in neonates born at term compared to those born prematurely (mean +/- SD, prealbumin 12.0 +/- 3.9 mg/dl vs. 8.8 +/- 2.3 mg/dl, p less than 0.001; RBP, 2.3 +/- 0.8 vs. 1.8 +/- 0.5 mg/dl, p less than 0.005). No significant differences between arterial and venous concentrations of prealbumin and RBP were observed in cord blood. In maternal blood, serum prealbumin and RBP concentrations did not increase with length of gestation (25-42 weeks). Maternal prealbumin was not correlated significantly with infants' cord serum levels; the correlation coefficient for RBP was 0.29, p less than 0.05. Maternal prealbumin and RBP serum levels were approximately twice the values seen in neonates born both at term and prematurely. Although the difference between premature and full-term cord levels of prealbumin and RBP may reflect an increase in hepatic protein synthesis that occurs with maturation of the fetus and/or a change in placental function after 37 weeks gestation, neither of these factors sufficiently explains the variance in neonatal prealbumin and RBP levels.     

Cord transferrin and ferritin values in newborn infants at risk for prenatal uteroplacental insufficiency and chronic hypoxia

We measured cord transferrin and ferritin levels in 50 newborn infants with fetal conditions associated with either uteroplacental vascular insufficiency or chronic hypoxia. Sixteen small for gestational age infants, 21 infants of mothers with preeclampsia, and 13 symptomatic infants of diabetic mothers had significantly higher transferrin levels and lower ferritin levels and calculated iron stores than did asymptomatic gestational age-matched control infants without these conditions. Cord ferritin levels and calculated iron stores were significantly lower in the infants of diabetic mothers than in any other group of infants. Cord transferrin levels were inversely correlated with ferritin levels (r = -0.59, P less than 0.001) and were unrelated to transthyretin levels and birth weight in the high-risk infants, but were positively correlated with ferritin levels (r = 0.50, P less than 0.001), transthyretin levels (r = 0.65, P less than 0.001), and birth weight (r = 0.75, P less than 0.001) in the control infants. We conclude that cord transferrin levels do not reflect protein-energy status in newborn infants with prenatal histories suggesting uteroplacental insufficiency or chronic hypoxia, and that when associated with decreased cord ferritin levels, indicate possible impaired iron stores in these infants.     

Risk factors for small-for-gestational-age babies: The Auckland Birthweight Collaborative Study

OBJECTIVE: This case-control study determined whether internationally recognized risk factors for small-for-gestational-age (SGA) term babies were applicable in New Zealand. METHODOLOGY: All babies were born at 37 or more completed weeks of gestation in one of three hospitals in Auckland. Cases weighed less than the sex specific 10th percentile for gestational age at birth, and controls (appropriate-for-gestational-age (AGA)) were a random selection of heavier babies. Information was collected by maternal interview and from obstetric databases. RESULTS: Information from 1714 completed interviews (844 SGA and 870 AGA) was available for analysis. Computerized obstetric records were available for 1691 of the 1701 women who consented to such access. In a multivariate analysis allowing for sex, gestational age at birth, social class and other potential confounders, mothers who smoked had a significantly increased risk of an SGA baby (adjusted OR 2.41; 95% CI 1.78-3.28), as did primiparous mothers (adjusted OR 1.34; 95% CI 1.03-1.73), mothers of Indian ethnicity (adjusted OR 3.22; 95% CI 1.95-5.30), women with pre-eclamptic toxaemia (adjusted OR 2.42; 95% CI 1.08-5.40) and those with pre-existing hypertension toxaemia (adjusted OR 5.49; 95% CI 1.81-16.71). Mothers of SGA infants were shorter (P < 0.001) and reported lower prepregnancy body weights (P < 0.001) than mothers of AGA infants. The population attributable fraction for smoking suggests that up to 18% of SGA infants born in the ABC Study could be related to maternal smoking. CONCLUSIONS: Risk factors associated with SGA births in other countries are also important in New Zealand. Smoking in pregnancy is an important and potentially modifiable behaviour, and efforts to decrease the number of women who smoke during pregnancy should be encouraged.     

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。     

Asymptomatic hyperammonemia in low birthweight infants

At 0-3 days of age the plasma ammonium concentration in full term appropriate for gestational age (AGA) infants was (mean +/- SEM) 27.5 +/- 0.5 micron; a value similar to that reported in adults. Ammonium levels in low birthweight AGA and SGA groups were 47.0 +/- 2.0 micron and 45.1 +/- 3.3 micron respectively; significantly elevated (P less than 0.001) as compared to the full term group. These increased ammonium levels persisted at 3-5 weeks of age. Associated with the hyperammonemia was a significant (P less than 0.01) decrease in plasma alpha-ketoglutarate concentration: 11.8 +/- 1.0 micron, in the low birthweight AGA as compared to 20.7 +/- 0.6 micron in the full term AGA infants. There was an inverse linear correlation between plasma concentrations of ammonium and alpha-ketoglutarate r = -0.86, P less than 0.001. Urinary orotate excretion was significantly elevated (P less than 0.05) in low birthweight AGA infants. There was no difference in the plasma concentrations of glutamine, glutamate, or alanine among the various groups. Hyperammonemia was not associated with neurologic dysfunction.