Vitamin D levels and insulin resistance in children born with severe growth restriction.

This study was designed to examine differences in serum 25(OH)D levels between small-for-gestational-age (SGA) and appropriate-for-gestational-age (AGA) prepubertal children in correlation with birth weight and indices of insulin resistance and ß-cell function. Sixty-five nonobese children were examined at age 5-7.5 years; 27 born SGA and 38 matched AGA. Body weight, height, BMI, and waist circumference were recorded and fasting serum levels of glucose, insulin, 25(OH)D, and parathyroid hormone (PTH) were measured. The homeostasis model assessment for insulin resistance (HOMA-IR) and the ß-cell function index (HOMA-ß%) were estimated. The mean level of 25(OH)D was higher in the SGA group (26.2±10 vs. 17.2±7 ng/ml, p<0.01) but that of PTH was no different. The insulin resistance and ß-cell function indices were higher in the SGA group: HOMA-IR 1.34±0.67 vs. 0.99±0.53, and HOMA-ß% 135±56 vs. 97±60 in the SGA and AGA groups, respectively. In the SGA group, 25(OH)D was correlated with HOMA-ß% but not with HOMA-IR or insulin. In multiple regression, in the total cohort 25(OH)D and HOMA-IR were independently negatively correlated with birth weight (ß= - 0.31, ß= - 0.36, p<0.05) respectively. In conclusion, at prepuberty severely in utero growth restricted children have increased birth weight dependent levels of 25(OH)D, which might exert a regulatory role on ß-cell function.

Serum insulin-like growth factor I (IGF-I), IGF-binding proteins-1 and -3, and postnatal growth of late preterm infants.

Late preterm infants may have impaired early growth. The role of circulating insulin-like growth factors (IGFs) in the regulation of postnatal growth of these infants is unclear. The aim of the study was to investigate prospectively the serum levels of IGFs during the first year of life in late preterm infants and their association with birth weight and early postnatal growth. The study was conducted on 112 infants, born appropriate for gestational age (GA) at GA 32-36 weeks. Serum levels of IGF-I and IGF-binding proteins (IGFBP) -1 and -3, and anthropometric measurements were recorded at the chronological age of 2 and 6 weeks, and 3, 6, 9, and 12 months. The mean levels of both IGF-I and IGFBP-3 were found to be lower at 2 and 6 weeks, 82±44, 100±31 ng/ml, and 1.7±0.8, 2.1±1 µg/ml, respectively, but then rose and remained stable between 3 and 12 months. The levels of IGFBP-1 were lower at the 3 first study points and increased gradually thereafter. Birth weight correlated positively with the level IGF-I at 2 and 6 weeks (R=0.35, 0.37; p<0.01), but negatively at 12 months (R= - 0.34; p<0.01), independent of other factors. At all study points up to 6 months, the level of IGF-I was higher in infants who showed more rapid growth in either body weight or crown heel length. In late preterm infants, the serum IGF-I level is closely related to early accelerated growth. Its diverse associations with birth weight may imply a regulatory effect on regression of growth towards the mean.

Visfatin levels in prepubertal children born small or large for gestational age.

Children born small (SGA) or large (LGA) for gestational age are prone to develop insulin resistance (IR) during childhood. Visfatin, a hormone with insulin-mimetic actions, has been associated with IR. This study was designed to examine whether serum level of visfatin is correlated with metabolic indices of IR, in prepuberty in association with the intrauterine growth pattern. The following parameters were evaluated at a mean age of 6.5±1.2 years in 155 prepubertal children born appropriate for the gestational age (AGA) (n=63), or SGA (n=42), or LGA (n=50): serum levels of visfatin, adiponectin, leptin, fasting glucose (G(F)) and insulin (I(F)), the homeostasis model assessment IR index (HOMA-IR), plasma lipids, anthropometric indices at birth and the time of evaluation, and obesity indices [waist circumference (WC), body mass index (BMI) and skinfold thickness]. The mean serum level of visfatin was lower in the SGA than in the AGA and the LGA children (9±5.2 vs. 11.8±5.1 and 12.7±5.6 ng/ml, respectively, p<0.01). Girls had lower visfatin levels than boys (10.4±4.3 ng/ml vs. 12.5±6.7 ng/ml, p<0.05). Visfatin was not correlated with IR indices. In multiple regression analysis visfatin level was positively correlated with birth weight z-score (t=2.56, beta=0.24, p<0.01) and crown to heel z-score (t=2.46, beta=0.22, p=0.014), independent of age, gender, maternal weight before pregnancy, maternal weight gain during pregnancy, BMI z-score, WC z-score, serum leptin and adiponectin, and HOMA-IR. In conclusion serum visfatin level was lower in prepubertal SGA children but not correlated with IR indices. Low birth weight was an independent predictor of visfatin level.

Vitamin D and parathormone levels of late-preterm formula fed infants during the first year of life.

BACKGROUND/OBJECTIVES: Preterm infants are at risk for low vitamin D but documentation on late-preterm infants is sparse. This prospective study monitored longitudinally vitamin D and parathormone (PTH) levels in late-preterm formula fed infants during the first year of life, taking into consideration in utero and postnatal growth, and season and diet. SUBJECTS/METHODS: The study population comprised 128 infants of gestational age (GA) 32-36 weeks, of which 102 were appropriate (AGA) and the remaining 26 were small for GA (SGA). Serum levels of vitamin D (25(OH)D), PTH calcium, phosphate (P) and alkaline phosphate were estimated at 2 and 6 weeks, and at 3, 6, 9 and 12 months of age. RESULTS: The 25(OH)D levels were relatively low at 2 and 6 weeks in both AGA and SGA infants (21±11, 20±7 ng/ml and 25±16, 23±8 ng/ml, respectively), but increased at 6 months (45±14, 47±10 ng/ml) and remained stable thereafter. SGA infants had lower 25(OH)D levels at 9 and 12 months (AGA 45±14, 47±18 ng/ml vs SGA 38±13, 37±13 ng/ml, P<0.05). Deficiency of 25(OH)D (<20 ng/ml) was found in 18.5% of measurements in 92 (72%) infants, and its insufficiency (20-32 ng/ml) was found in 29.2% of measurements in 99 (77.3%) infants. Most measurements with vitamin D <32 ng/ml were observed at the first three study points, where PTH showed an inverse association with 25(OH)D, reaching a plateau thereafter. CONCLUSIONS: Late-preterm, formula fed infants may have suboptimal vitamin D levels and elevated PTH, especially, during the first 3 months. Those born SGA may have lower vitamin D levels up to the end of the first year of life.

Growth factors, adiponectin, leptin and body mass index in pre-pubertal children born large for gestational age.

OBJECTIVE: To examine whether the IGF axis in pre-pubertal children born large for gestational age (LGA) differs from that of those born appropriate for gestational age (AGA). RESEARCH DESIGN AND METHODS: The study population consisted of 98 non-obese children aged 5.5-8 yr, of whom 37 were LGA, with birth weight (BW) > 90th percentile, and 61 AGA. The LGA children were subdivided into two subgroups, with BW 90th-97th percentile (no.=24) and BW > 97th percentile (no.=13), respectively. Total and free IGF-I, their binding proteins 1 and 3 (IGFBP-1 and IGFBP-3), leptin, adiponectin, fasting glucose (GF) and insulin (IF) were measured, and the homeostasis model assessment for insulin resistance (HOMA-IR index) was determined. RESULTS: IGF-I, free IGF-I and IGFBP-1 were similar in both groups. Both LGA subgroups had lower IGFBP-3 levels than the AGA group (2.34 ± 0.61 and 2.70 ± 0.90, respectively, vs 3.92 ± 1.1 µg/ml, p < 0.01). Adiponectin was higher in the 90th-97th percentile LGA subgroup than the AGA group (p<0.01). GF and IF were higher in the LGA group (86.5 ± 5.6 mg/dl, p < 0.01, and 5.84 ± 2.13 µU/ml, respectively, p < 0.05) than in the AGA group (82.6 ± 7.7 mg/dl and 4.62 ± 1.9 µU/ml, respectively), as was the HOMA-IR index (1.27 ± 0.60 vs 0.94 ± 0.43, p < 0.01). These three parameters were also found higher in the >97th percentile LGA subgroup. CONCLUSION: The IGF axis was not different in pre-pubertal children born LGA or AGA, with the exception of IGFBP-3, which was lower in the LGA children. In LGA pre-pubertal children the severity of intrauterine overgrowth was associated with the insulin resistance indices.

Effect of aminoglycoside therapy on renal function in full-term infants.

The effect of aminoglycosides on renal function was evaluated in 30 full-term infants who were treated within 24 h of birth with either amikacin (10 infants, group A), gentamicin (9 infants, group B), or netilmicin (10 infants, group C). Renal function was assessed before, during, and 48 h after discontinuation of therapy by measuring the plasma creatinine concentration (PCr), the fractional excretion of sodium (FENa), potassium, magnesium, phosphate (FEP), uric acid, and the urinary excretion of calcium (UCA/UCr ratio) immediately before (trough) and after (peak) the infusion of the aminoglycosides. The results were compared with 10 control newborns who did not receive antibiotics. Significant alterations in renal function were observed only during therapy with gentamicin (group B). These consisted of a sustained elevation of FENa and UCa/UCr ratio throughout therapy, a latent increase in FEP on the 7th day (P < 0.05), and lack of the normal postnatal decline of PCr in 3 of 9 infants (P < 0.01). These abnormalities persisted up to 2 days after discontinuation of therapy. Therapeutic doses of gentamicin may result in significant electrolyte disturbances in sick full-term infants.

Renal function in premature infants during aminoglycoside therapy.

The effect of three different aminoglycosides on renal function was evaluated in 30 premature infants of similar gestational age who were treated within 24 h of birth with either amikacin (10 infants, group A), gentamicin (10 infants, group B) or netilmicin (10 infants, group C), for a period of 7 days. Ten infection-free premature infants of similar post-conceptional age were used as controls. Serial determinations of plasma creatinine concentration (PCr), as well as the fractional excretion of sodium (FENa), potassium, magnesium (FEMg), phosphate (FEP) and uric acid (FEUA), and the urinary excretion of calcium (UCa/UCr ratio) were assessed before, during and after treatment. During the treatment period a significant increase in FENa, FEMg and UCa/UCr was observed in group B (P < 0.05 and P < 0.01, respectively) and an increase in FENa and UCa/UCr in group C (P < 0.01) compared with controls. These disturbances were observed with trough concentrations of aminoglycosides but were accentuated at peak serum concentrations and were restored to normal 2 days after stopping therapy. In addition, a significant correlation was demonstrated between FENa, FEMg and UCa/UCr ratio in treated patients. PCr levels decreased similarly in all patient groups, but in 8 of 30 infants (27%) they remained elevated and returned to control values only 10 days after stopping therapy. Such renal functional disturbances, although transient, may result in significant electrolyte and mineral imbalance in the sick premature infant.