肾病综合征患儿血清铁与转铁蛋白的变化

目的：肾病综合征(NS)患儿尿中丢失白蛋白的同时也伴有转铁蛋白的丢失,测定血清铁及转铁蛋白等铁代谢相关指标以及尿转铁蛋白,了解其变化及其相互关系。方法：NS患儿37例,测定其治疗前和恢复期铁代谢相关指标(血清铁、铁蛋白、转铁蛋白、转铁蛋白饱和度、总铁结合力以及外周血红细胞参数)及尿转铁蛋白,并与正常对照组比较。结果：①在NS治疗前血清铁为18.8±3.8μmol/L,分别与恢复期的21.0±3.5μmol/L,及对照组的22.2±3.8μmol/L比较,差异有显著性(P<0.01);转铁蛋白为1.9±0.3g/L,分别与恢复期的2.9±0.6g/L和对照组的3.1±0.5g/L比较,差异有显著性(P<0.01);总铁结合力为56.4±9.2μmol/L,分别与恢复期的51.9±7.7μmol/L和对照组的50.7±6.8μmol/L比较,差异亦有显著性(均P<0.01);转铁蛋白饱和度为(55.7±9.2)%,与NS恢复期及对照组的(47.4±13.3)%,(46.4±8.2)%比较,差异有显著性(P<0.01)。②血清白蛋白与转铁蛋白呈正相关(r=0.609,P<0.01)。③血清转铁蛋白浓度与尿转铁蛋白呈负相关(r=-0.550,P<0.01)。结论：NS患儿血清铁及转铁蛋白明显降低,可能与转铁蛋白从尿中丢失有关。     

Stimulation of collagen synthesis and linear growth by growth hormone in glucocorticoid-treated children.

Impaired linear growth and skeletal maturation associated with chronic glucocorticoid therapy may result from (1) inhibited insulin-like growth factor 1 (IGF-1) activity; (2) impaired type 1 collagen synthesis; or (3) suppressed growth hormone (GH) secretory response to growth hormone-releasing hormone. Each mechanism could potentially be improved by exogenous GH treatment. Seven slowly growing glucocorticoid-treated children received recombinant DNA human GH (0.3 mg/kg/per week) for 6 to 21 (mean 13.1 +/- 4.9) months. Height, weight, IGF-1 activity, glycosylated hemoglobin level, and C-terminal type 1 procollagen level were measured every 3 months and growth velocity was calculated. Skeletal maturation and 2-hour postprandial serum glucose and insulin levels were assessed every 6 months. All patients showed increased growth velocity during treatment with GH. Mean growth velocity increased from 3.43 +/- 0.65 cm/y to 6.72 +/- 0.84 cm/y with GH therapy (P less than .005). Growth velocity standard deviation scores corrected for bone age (P less than .005), IGF-1 levels (P less than .05), and C-terminal type 1 procollagen levels (P less than .005) also increased with GH therapy. C-terminal type 1 procollagen levels correlated well with growth velocity (r = .652) while IGF-1 levels did not (r = .17). Glycosylated hemoglobin levels remained unchanged, but 2-hour postprandial glucose levels rose during GH treatment. Slowly growing glucocorticoid-treated children receiving GH therapy increased growth velocity for 6 to 21 months. Initially diminished C-terminal type 1 procollagen levels rose with GH therapy, a change which corresponded with growth acceleration.(ABSTRACT TRUNCATED AT 250 WORDS)     

Treatment of diabetes in children under 3 years of age. Indications, methods and results

Before modern methods of diabetes management were available, the achievement of strict glycemic control was considered almost impossible in most children with early onset of the disease. The present results obtained over 2 years in 31 children aged 21 +/- 2 (SEM) months at the onset of the disease indicate the efficiency of intensive conventional therapy in 21 of them: glycosylated hemoglobin averaged 7.0 +/- 0.3% (N = 4.7 +/- 0.7%) during the observed 26 +/- 7 months, with only 0.02 +/- 0.01 hypoglycemic attack per patient-month and no diabetic ketoacidosis. In the remaining 10 children, who resisted intensive conventional therapy, we used insulin pumps to improve blood glucose control, with the following results over 21 +/- 4 months: Glycosylated hemoglobin decreased from 9.3 +/- 0.3% (before pump) to 8.0 +/- 0.4% (p less than 0.05). The frequency of hypoglycemia decreased dramatically from 1.7 +/- 0.7 to 0.03 +/- 0.01 episode per patient-month. The frequency of ketonuria and ketoacidosis was unchanged. We concluded that intensification of therapy through conventional means, or pump treatment if necessary, allows a long term efficient control of blood glucose in preschool children.     

Myocardial dysfunction in children with acute meningococcemia

Acute meningococcemia is frequently associated with cardiovascular collapse of uncertain cause. Review of the records of 12 consecutive children revealed clinical evidence of myocardial dysfunction in six (50%). Subsequently myocardial function was prospectively assessed clinically and echocardiographically in 12 children. Seven (58%) of the 12 children had echocardiographic evidence of myocardial dysfunction as defined by a depressed left ventricular shortening fraction (LVSF). The mean LVSF in these seven children was 0.25 +/- 0.03, as compared with the mean LVSF of 0.39 +/- 0.7 in the remaining children. The LVSF estimate of myocardial function strongly correlated with cardiac output as measured by standard thermodilution (r = 0.98, P less than 0.01). Acute meningococcemia was not fatal in those children without evidence of myocardial dysfunction. In contrast, three of the seven children with evidence of myocardial dysfunction died. In four children, echocardiographic evidence of left ventricular dysfunction preceded cardiovascular collapse and clinical recognition of myocardial dysfunction. In children with an initially low LVSF, recovery of LVSF was associated with survival. Children with acute meningococcemia may have impaired myocardial function as indicated by depressed LVSF, resulting in low cardiac output despite normal intravascular volume. Thus, in addition to restoring intravascular volume, knowledge of the status of myocardial function may help direct therapy toward optimizing myocardial contractility.     

Effect of calcium therapy in the sick premature infant with early neonatal hypocalcemia

Twenty-seven sick premature infants with serum calcium concentrations less than 6.0 mg/dl during the first day of age were enrolled in a prospective controlled study involving two treatment regimens--calcium given as a bolus or a drip--or no treatment. Mean total calcium concentration was 5.5 +/- 0.8 mg/dl, and ionized calcium was 3.1 +/- .3 mg/dl, with no significant difference between treatment groups. By 24 hours, in all groups total calcium had increased to greater than 6.0 mg/dl (bolus 6.5 +/- 1.1, drip 7.0 +/- 0.4, control 6.6 +/- 0.4) and ionized calcium to greater than 3.5 mg/dl (bolus 3.9 +/- 0.3, drip 3.6 +/- 0.6, control 3.6 +/- 0.3). Ionized and total calcium concentrations were significantly correlated (r = 0.562; P less than 0.001), but total calcium did not predict ionized calcium in any group. These data support the concept that, even in sick infants, early neonatal hypocalcemia is a physiologic phenomenon that may not require treatment.     

Diabetes mellitus associated with cystic fibrosis

The prevalence of overt diabetes mellitus and carbohydrate intolerance was studied in 448 patients with cystic fibrosis (CF). Insulin-dependent diabetes (IDDM) developed in 7.6% of patients (13 male and 21 female). Survival was significantly lower (P less than 0.01) in the IDDM-CF group, with fewer than 25% surviving to age 30 years, whereas nearly 60% of the nondiabetic CF population reached this age. A significant deterioration in CF clinical status, based on NIH score, became apparent 2 years before onset of overt IDDM (P less than 0.05 at 2 years prior, P less than 0.01 at IDDM diagnosis). Total glycosylated hemoglobin (HbA1) was significantly (P less than 0.001) higher for the total CF population (7.3% +/- 1.2%) than for the general non-CF population (6.5% +/- 0.7%), and in the IDDM-CF group (P less than 0.05) compared with normoglycemic CF control patients. Female patients had a higher mean HbA1 after 12 years of age than their male counterparts did (P less than 0.02). HBA1 did not predict the development of IDDM, but there was a weak inverse relationship between HbA1 and both NIH clinical score (r = -0.41, P less than 0.02) and standard pulmonary function tests (forced vital capacity, r = -0.25, P less than 0.01) in the general CF population. Therefore, impaired carbohydrate tolerance in CF is associated with progressive clinical deterioration.     

Improved erythrocyte survival with combined vitamin E and selenium therapy in children with glucose-6-phosphate dehydrogenase deficiency and mild chronic hemolysis

To study the antioxidant effect of high-dose vitamin E alone and in combination with selenium in patients with glucose-6-phosphate dehydrogenase deficiency with mild chronic hemolysis, 36 male children with such manifestations were enrolled consecutively into two equal groups. Group 1 received 800 IU vitamin E daily, and group 2 received 800 IU vitamin E in combination with 25 micrograms selenium. Hematologic status before and 2 months after treatment was evaluated. After treatment there was a significant change toward normal in both groups. The mean red cell half-life increased in group 1 from 16.9 to 22.8 days (P less than 0.01), and in group 2 from 15.6 to 24.3 days (P less than 0.01). A comparison of the mean difference of paired values in the two groups revealed a more significant increase in hemoglobin (0.9 +/- 0.1 gm/dl vs 1.2 +/- 0.2 gm/dl, P less than 0.05), hematocrit (2.4% +/- 0.4% vs 3.8% +/- 0.3%, P less than 0.05), and red cell half-life (5.9 +/- 3.0 days vs 9.1 +/- 4.4 days, P less than 0.01), and more significant reduction in reticulocytes (-0.7% +/- 0.2% vs -1.5% +/- 0.4%, P less than 0.01) in group 2. Clinical assessment and follow-up indicated no side effects related to the drugs.     

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.     

Iron-deficiency anaemia and its response to oral iron: report of a study in rural Gambian children treated at home by their mothers

Haematological and iron parameters, measured in 907 children aged from 6 months to 5 years in rural Gambia at the start of the rainy season, differed from those in American reference populations as follows: mean haemoglobin levels were much lower at ages 1 and 2 years and mean levels of mean corpuscular volume (MCV) were lower at all ages (at age 1 year mean haemoglobin was 11.2 g/dl and mean MCV 68.2 fl); in a sample of 249 children randomly selected from the whole study population, mean serum iron levels were similar but mean transferrin saturation and mean serum ferritin levels were lower, especially at ages 1-3 years (at age 1 year mean serum iron was 11.1 mumol/l, mean transferrin saturation 16.9%, and geometric mean serum ferritin 8.8 ng/ml. A total of 213 children (23%) whose haemoglobin and mean corpuscular volume were both less than the 3rd percentile of the reference population received oral iron or placebo from their mothers during the rainy season when malaria transmission is maximal. Mean levels of haemoglobin, mean corpuscular volume, serum iron, transferrin saturation and serum ferritin rose in the iron-treated group and fell in the placebo group at all ages, except under 1 year for serum ferritin, to produce significant differences between the groups by the end of the study. Total iron-binding capacity showed no significant changes during the study. We concluded that oral iron given by the mother during the rainy season can be used to treat iron-deficiency anaemia in Gambian children who would otherwise become more anaemic.     

Decreased prolactin secretion in childhood obesity

Twelve obese patients and 7 control subjects, age and sex matched, whose weights were greater than 200% of ideal weight and 100% of ideal body weight, respectively, underwent intravenous insulin and thyroid releasing hormone (TRH) tests. Serial prolactin growth hormone, insulin, blood sugar, cortisol, glucagon, thyrotropin stimulating hormone, thyroxine, and triiodothyronine were obtained by RIA. Obese patients showed no significant differences from controls in basal and nadir glucose, basal and peak glucagon, cortisol, and thyroid responses to both tests. Basal insulin levels were higher (36 +/- 9.4 vs 10 +/- 2.3 microU/ml, P less than 0.05) and peak growth hormone responses after insulin were lower in the obese group (6.1 +/- 1.1 vs 12.7 +/- 3.7 ng/ml, P less than 0.05) than in controls. Whereas all control subjects had prolactin responses to both tests, five of 12 obese patients had no responses to insulin. Obese patients had lower prolactin responses at 30 minutes after insulin (5.4 +/- 0.7 vs 12.9 +/- 3.7 ng/ml, P less than 0.05) and lower prolactin responses at 60 minutes after TRH (9.9 +/- 1.7 vs 20.4 +/- 5.9 ng/ml, P less than 0.05). Maximum prolactin responses after TRH were lower in obese patients (9.9 +/- 2.0 vs 28.8 +/- 10.9 ng/ml, P less than 0.05). Maximum prolactin responses after insulin were lower in obese patients (6.2 +/- 4.1 vs 28.9 +/- 18.3 ng/ml). Thus prolactin secretion in childhood obesity is decreased after both stimuli, but more so after IV insulin that TRH, and suggests that, as in adult hypothalamic obesity, neuroendocrine regulation of prolactin release in obese children is impaired.     

Plasma renin activity related to sodium balance, renal function and urinary vasopressin in the newborn infant.

Plasma renin activity was determined in 25 healthy, full-term, newborn infants aged 1 day to 9 weeks. High values were found, the mean level at 1-2 days of life (24.8 +/- 8.4 ng/ml/hr, SE) being significantly higher than the mean levels at 7-9 days (5.8 +/- 1.5) and at 4-9 weeks (8.1 +/- 1.3) (P less than 0.05). No correlation was found between plasma renin activity and systolic blood pressure, hematocrit, creatinine clearance, serum sodium, or serum potassium. Plasma renin activity (log values) was inversely correlated with sodium intake (r = -0.58) or with urinary sodium (r = -0.44), and positively with urinary osmolality (r = 0.67). The correlations reached higher coefficients if only infants aged less than or equal to 9 days were considered. In addition, vasopressin was measured by radioimmunoassay in the urine. The daily excretion was lower in newborn infants (9.4 +/- 1.6 ng/m2/day, SE, at 1-2 days of postnatal life) than in healthy children (37.1 +/- 5.6), and was significantly correlated with creatinine clearance (r = 0.69), but not with urinary osmolality.     

The syndrome of inappropriate secretion of antidiuretic hormone in children with bacterial meningitis

Plasma concentrations of arginine vasopressin were determined by radioimmunoassay in 13 normal children, 21 patients with febrile illnesses (not bacterial meningitis), and 17 patients with bacterial meningitis. The mean +/- 1 SD concentrations of AVP in the normal children and patients with various febrile illnesses were 0.7 +/- 0.6 and 1.0 +/- 1.2 muU/ml, respectively. The mean +/- 1 SD concentration of AVP in patients with bacterial meningitis was 3.3 +/- 2.3 muU/ml. The concentrations of AVP in the patients with bacterial meningitis were significantly greater (P less than 0.001) than those noted in the normal children or children with other febrile diseases.     

Hormone ontogeny in the ovine fetus. IV. Serum somatomedin activity in the fetal and neonatal lamb and pregnant ewe: correlation with maternal and fetal growth hormone, prolactin, and chorionic somatomammotropin.

Somatomedin (SM) activity was measured by a placental membrane receptor assay using 125I-labeled somatomedin A, as radioligand in serum samples obtained from 33 ovine fetuses, 14 neonatal lambs, 8 pregnant, and 3 postpartum ewes. The mean serum concentration of SM activity in eight adult rams was 2.06 +/- 0.12 U/ml. In fetal sheep, SM activity was detected at 66 days gestation (term 147 days), in the youngest fetus studied. Before 100 days of gestation, SM was lower (P less than 0.001) in fetal sheep (1.08 +/- 0.18 U/ml) than in adult rams. In fetuses between 101 and 125 days, SM rose (P less than 0.001) to 2.64 +/- 0.32 U/ml. In late gestation fetal serum SM fell but during the neonatal period it rose to 3.38 +/- 0.3 U/ml, higher (P less than 0.01) than that in adult rams. Serum SM activity in the pregnant ewe prior to 100 days was 1.01 +/- 0.11 U/ml, increased (P less than 0.05) to 1.75 +/- 0.21 U/ml between 125 days and term, and rose further to 2.56 +/- 0.32 U/ml in the postpartum period. Maternal concentrations of serum SM in late gestation were significantly less than in the fetus. Gel chromatography of fetal, maternal, and neonatal sera indicated that over 90% of SM activity circulated in high-molecular weight form. The rise in SM activity in fetal serum between 100 and 125 days parallels the rise in fetal growth hormone and prolactin concentrations; however, in maternal serum the increase in SM activity is associated with rising maternal chorionic somatomammotropin concentrations.     

Quality-protein maize as the sole source of dietary protein and fat for rapidly growing young children

Earlier studies demonstrated that quality protein maize (QPM), with increased lysine and tryptophan and decreased leucine contents, was more digestible and supported 45% greater nitrogen retention than common maize. Ten recovering malnourished children (ages 13 to 29 months, height-ages 5 to 15 months, weight-ages 3 to 11 months) have now received 90% of their diet energy and 100% of protein and fat from QPM. Energy intake was adjusted to allow them to reach the 50th centile of weight-for-length (according to the National Center for Health Statistics) in 90 days (two completed 60 days only). Growth was compared with that of 10 children receiving modified cow's milk formula (CMF). Energy intakes (QPM 110 +/- 15, CMF 106 +/- 12, corrected for absorption to 94 and 97 kcal/kg.d), crude energy costs of gain (43 +/- 9 and 40 +/- 10, corrected to 37 and 37 kcal/g), linear growth (1.23 +/- 0.24 and 1.33 +/- 0.26 cm/mo), gains in height-age (3.1 +/- 0.7 and 3.3 +/- 1.2 mo), weight gain (2.6 +/- 0.6 and 2.6 +/- 0.8 g/kg.d), and final sums of fat folds (24.3 +/- 3.5 and 27.2 +/- 2.9 mm) were not different. Gains in weight-age were greater (7.5 +/- 2.3 vs 5.4 +/- 1.6 months, P less than .05) and serum albumin decreased (4.10 +/- 0.24 to 3.77 +/- 0.31 g/dL, P less than .01) during QPM feeding. Plasma-free total essential amino acids and ratio of these to total essential amino acids were less after QPM than after CMF diets. Equal growth rates with QPM and CMF diets offer great potential for developing- and developed-country children.     

Iron deficiency anemia and catecholamine metabolism

To assess the effects of iron therapy on platelet monoamine oxidase (MAO) activity and urinary excretion of total metanephrines (MN) in infants and young children with iron deficiency anemia, 24 subjects were tested before and after one month of oral iron treatment. Thirteen healthy children comprised the control group. In the control group, platelet MAO level was 0.21 +/- 0.02 U/mg protein (mean +/- SE), urinary total metanephrine was 2.51 +/- 0.47 micrograms/mg creatinine. In cases with iron deficiency, mean platelet MAO level was 47.6% lower (p less than 0.005) whereas mean urinary metanephrine plus normetanephrine (MN-NMN) was only 20.7% lower (p greater than 0.05) than the control values. After one month, the anemic patients receiving oral iron therapy showed a significant increase in hemoglobin concentration, per cent transferrin saturation and platelet MAO activity (p less than 0.05). However, urinary metanephrine excretion was found to be lower in this group when compared to the metanephrine levels in iron deficiency before the medication (p less than 0.05). Although hemoglobin and transferrin saturation did not return to normal levels, these findings suggested that platelet MAO activity increased and urinary excretion of metanephrines decreased after iron medication.     

A single food bolus stimulates albumin synthesis in growing piglets

BACKGROUND: A stable isotope tracer method to quantify the synthesis of proteins of hepatic origin in response to feeding is described. The response of albumin synthesis on one mixed meal in a piglet model was investigated and the intragastric and intravenous administration modes of 13C-valine were compared. METHODS: The fasting and postprandial fractional synthesis rates (FSRs) of albumin in 15 piglets were measured while infusion rates of 13C-valine were changed in anticipation of the increased appearance of the tracee after a single liquid food bolus (30 mL/kg infant formula). 13C-valine enrichments in albumin hydrolysates at regular time intervals were determined with gas chromatography-combustion isotope ratio mass spectrometry. RESULTS: The intravenous mode (n = 8) showed constant plasma alpha-ketoisovalerate tracer-to-tracee ratios (coefficient of variation range: 1-8%), and a 27% increase in albumin FSR after the food bolus (mean FSR +/- standard error [SE]: fasting 14.4% +/- 1.6% vs. postprandial 18.3% +/- 2.2% per day; P < 0.005). In the intragastric mode (n = 7), albumin FSR calculated from the mean precursor values increased 32% after feeding (fasting 14.6% +/- 1.5% vs. postprandial 19.3% +/- 1.6% per day; P = 0.005), despite absence of constant alpha-ketoisovalerate enrichment (coefficient of variation range: 15-31%). The FSRs were not significantly different between both infusion modes. CONCLUSIONS: A mixed food bolus increases albumin FSR in growing piglets by approximately 30%, irrespective of the tracer administration route. The concept of anticipated precursor steady state is applicable to study changes of hepatic protein synthesis after a single meal. The intragastric mode of tracer administration can be applied as a less invasive method to measure tissue specific protein synthesis in children.     

Oral breathing in newborn infants

Newborn infants are considered obligate nasal breathers, hence dependent on a patent nasal airway for ventilation. The conditions under which oral breathing could occur and the contribution of oral ventilation to total ventilation were studied in 30 healthy term infants (aged 1 to 3 days). Nasal and oral airflow were measured using two resistance-matched pneumotachometers, and heart rate, tcPO2, etCO2, and sleep state were continuously recorded. In three of 10 infants studied in undisturbed sleep, spontaneous oronasal breathing was noted during both active and quiet sleep (mean duration 19 +/- 25 minutes), the distribution of tidal volume being 70% +/- 12% nasal and 30% +/- 12% oral. Episodes of oronasal breathing were also observed after crying in six infants (mean duration 21 +/- 19 seconds). In an additional 20 infants, multiple 15-second end-expiratory nasal occlusions were performed; eight (40%) of these infants initiated and sustained oral breathing in response to nasal occlusion. Respiratory rate, tidal volume, heart rate, and tcPO2 did not change when oral breathing occurred in response to nasal occlusion, although minute ventilation decreased from 265 to 199 ml/min/kg (P less than 0.05). These results demonstrate that newborn infants may use the oral airway for ventilation, both spontaneously and in response to complete nasal occlusion.     

Mineral homeostasis in very premature infants: serial evaluation of serum 25-hydroxyvitamin D, serum minerals, and bone mineralization

This study was designed to evaluate the role of vitamin D sufficiency, as reflected in serum 25-hydroxyvitamin D (25-OHD) concentrations, on serum minerals and bone mineralization in very premature infants. Seventy-two infants (mean +/- SD gestation 30.1 +/- 2.5 weeks, mean +/- SD birth weight 1178 +/- 278 gm) were observed serially for the first 3 months of life. Mean serum calcium and phosphorus values, but not magnesium, remained low prior to 12 weeks. The percentage of infants with moderate to severe hypomineralization was 75% at 3 weeks, 55% at 6 weeks, 54% at 9 weeks, and 15% at twelve weeks. Low serum calcium and phosphorus values, high alkaline phosphatase activity, and moderate-severe hypomineralization were more frequent in infants weighing less than 1000 gm and in those with lower mineral intake. With a 400 IU vitamin D supplement, 45% of infants could maintain an initially normal serum 25-OHD concentration or increase low concentrations, whereas 55% had falling or persistently low (less than or equal to 15 ng/ml) 25-OHD concentrations. Birth weight and mineral intakes were comparable in these two groups, yet the group with the lower serum 25-OHD concentration had lower serum calcium and higher alkaline phosphatase values, and a higher percentage of moderate to severe hypomineralization. Regardless of birth weight, mineral intake, or 25-OHD concentration, increases in serum calcium and phosphorus values and in mineralization were seen at postconception term (12 weeks in most infants, nine weeks in those weighing 1250 to 1600 gm). At 12 weeks of age, but not before, serum 25-OHD concentration was directly correlated with serum calcium (r = 0.47, P less than 0.01) and serum phosphorus (r = 0.47, P less than 0.01) and inversely correlated with alkaline phosphatase values (r = -0.71, P less than 0.01). Mineral availability and 25-OHD sufficiency both appear to be important and to act synergistically, with neither totally compensating for the other.     

A simple estimate of glomerular filtration rate in full-term infants during the first year of life

An estimate of glomerular filtration rate has been derived for children from body length (L, in centimeters) and plasma creatinine (Pcr, in milligrams per deciliter): GFR = 0.55 L/Pcr. The near universality of this estimate in children led us to seek a similar formula for estimating GFR in full-term infants during the first year of life. We measured Pcr in 137 healthy infants and performed creatinine clearance (Ccr) studies in 63 of them aged greater than or equal to 5 days. Beyond the first week, Pcr averaged 0.39 +/- 0.01 (0.10 SD) mg/dl. The estimate of GFR from 0.55 L/Pcr overestimated Ccr by 24% (P less than 0.001). Based on the calculation of a new constant from Ccr X Pcr/L, GFR was more accurately estimated from 0.45 L/Pcr (mean difference of Ccr - 0.45 L/Pcr = -0.4 +/- 3.7 (SE) ml/min X 1.73 m2) in full-term infants between 1 and 52 weeks of age. Because the constant 0.45 and Pcr do not change significantly during this period, GFR can be approximated at the bedside from body length of the healthy full-term infant (GFR = 0.45 L/0.39 = 1.1 L).     

Differentiation of transient hyperammonemia of the newborn and urea cycle enzyme defects by clinical presentation

We reviewed clinical data in 33 patients with transient hyperammonemia of the newborn (THAN): six previously unreported cases and 27 from the literature. Thirteen neonates with urea cycle enzyme deficiencies (UCED) served for comparison. No differences were found in the incidence of perinatal complications, route of delivery, Apgar scores, sex, or incidence or time of onset of seizures. On the other hand, neonates with THAN had significantly lower birth weights (mean +/- SEM 2282 +/- 78 gm vs 3336 +/- 222 gm, P less than 0.001) and gestational ages (35.1 +/- 0.5 weeks vs 39.6 +/- 0.5 weeks, P less than 0.001). Mean time of onset of respiratory distress (3.9 +/- 1.4 hours vs 71.5 +/- 26.1 hours, P less than 0.001), ventilatory support (P less than 0.001), lethargy (P less than 0.005), and coma (P less than 0.005) occurred earlier in THAN. Distinctive laboratory findings in patients with THAN included abnormal chest radiographic findings and plasma ammonium concentrations that were higher (1871 +/- 209 microM vs 973 +/- 169 microM, P less than 0.02) at an earlier age. Respiratory distress occurred in all but one patient with THAN before 24 hours; in contrast, only 62% of infants with UCED had respiratory symptoms, and none before 30 hours. In this retrospective study, the clinical presentation alone differentiated THAN from UCED.