Growth hormone, insulin like growth factor-1, and insulin-like growth factor-binding protein-3 levels in the neonatal period: a preliminary study

Umbilical cord serum insulin-like growth factor-1 levels of infants of diabetic mothers are correlated with diastolic dysfunction detected by tissue Doppler echocardiography

Tissue Doppler echocardiography (TDI) is a convenient method to detect cardiac dysfunction in the infants of diabetic mothers (IDMs). Umbilical cord serum insulin-like growth factor-1 (IGF-1) is known to be higher in IDMs. We aimed to determine whether there is a relation between diastolic functions examined by TDI and cord serum IGF-1 levels of IDMs. Cord serum IGF-1 levels of 32 IDMs and 22 healthy infants were measured. The cardiac functions of the infants were evaluated by M-Mode and TDI. For statistical analysis, Mann-Whitney U and Spearman correlation tests were used for continuous variables, and the chi-square test was used for categorical variables. The cord serum IGF-1 levels of the IDMs were higher (p = 0.000). The left ventricle (LV) e', LVa', LV e'/a', and LV Tei index, indicating left ventricular diastolic dysfunction in IDMs, were detected (LV e' p = 0.016; LV a' p = 0.003; LV e'/ a' p = 0.000; LV Tei index p = 0.023). IDMs' cord serum IGF-1 levels were found weakly correlated with the interventricular septum (IVS) and left ventricle posterior wall (LVPW) thicknesses in M-Mode and LV e' and LV e'/a' in TDI (IVS r = 0.357, p = 0.008; LVPW r = 0.289, p = 0.034; LV e' r = 0.297, p = 0.029; LV e'/ a' r = 0.031, p = 0.014).

CONCLUSION

To our knowledge, this is the first study to examine the relationship between cord serum IGF-1 levels and diastolic functions of IDMs assessed by TDI. A weak correlation was found between IGF-1 levels and IVS and LVPW thicknesses in M-Mode and LV e' and LV e'/a' parameters in TDI, revealing diastolic dysfunction in IDMs.

WHAT IS KNOWN

• The umbilical cord blood serum IGF-1 level of IDMs is higher than in infants of healthy mothers. • Diastolic dysfunction is a well-studied and frequently observed consequence in IDMs.

WHAT IS NEW

• This is the first study to examine the relationship between cord serum IGF-1 levels and diastolic functions of IDMs assessed by TDI. • A weak correlation was detected between the median cord serum IGF-1 level of IDMs and the median values of IVS, LVPW, LV e', LV a', LV e'/a' ratio.

Dynamic Changes in Serum IGF-I and Growth During Infancy: Associations to Body Fat, Target Height, and PAPPA2 Genotype

CONTEXT

IGF-I is important for postnatal growth and may be of diagnostic value in infants suspected of pituitary disease; however, little is known about the impact of IGF-I and its determinants on infant growth. Importantly, detailed reference ranges for IGF-I and IGF binding protein-3 (IGFBP-3) concentrations during infancy are lacking.

OBJECTIVE

To evaluate the rapid changes in weight and length as well as their determinants in healthy infants, and to establish age- and sex-specific reference curves for IGF-I and IGFBP-3 in children aged 0 to 1 years.

DESIGN

Prospective longitudinal study.

SETTING

Cohort study.

PARTICIPANTS

A total of 233 healthy children (114 girls) with repeated blood samples during the first year of life.

MAIN OUTCOME MEASURE(S)

Serum concentrations of IGF-I and IGFBP-3, length velocity, weight velocity, and PAPPA2 (rs1325598) genotype.

RESULTS

Individual trajectories of length and weight velocities were sex specific. We provide detailed reference curves based on longitudinal data for IGF-I and IGFBP-3 during infancy. In both girls and boys, IGF-I decreased during infancy, whereas IGFBP-3 remained stable. IGF-I and IGFBP-3, but not PAPPA2 genotype, were positively associated with weight gain, but not with longitudinal growth. When stratified by sex, the association between weight gain and IGF-I only remained significant in girls.

CONCLUSIONS

Interestingly, we found a significant association between IGF-I and infant weight gain in girls, but not with longitudinal growth in the first year of life. Our findings highlight the role of IGF-I as an important anabolic hormone that is not limited to linear growth.

Growth hormone deficiency and replacement in children

Growth hormone deficiency (GHD) is a rare but treatable cause of short stature. The diagnosis requires a careful evaluation of clinical history, physical examination and appropriate interpretation of longitudinal growth, with specific features for each period of life. Other clinical findings, in addition to growth failure, may be present and can be related to the etiology and to associated hormone deficiencies. Despite more than 50 years since the first reports of provocative tests of growth hormone (GH) secretion for the diagnosis of GHD, the interpretation of the results remains a matter of debate. When GHD is confirmed, GH treatment is recommended. Treatment is effective and safe, but requires daily injections during many years, which can affect adherence. At the end of longitudinal growth, during the transition phase, it might be necessary to re-evaluate GH secretion. This review summarizes and updates the recent information related to GHD in children, as well the recommendations for treatment.

Neonatal Hypopituitarism: Approaches to Diagnosis and Treatment

Hypopituitarism is defined as a decreased release of hypophyseal hormones, which may be caused by disease of the pituitary gland disease or hypothalamus. The clinical findings of neonatal hypopituitarism depend on the causes and on presence and extent of hormonal deficiency. Patients may be asymptomatic or may demonstrate non-specific symptoms, but may still be at risk for development of pituitary hormone deficiency over time. Patient history, physical examination, endocrinological, radiological and genetic evaluations are all important for early diagnosis and treatment. The aim of this paper was to present a review of etiological factors, clinical findings, diagnosis and treatment approaches in neonatal hypopituitarism.

Growth hormone signaling in fibroblasts from newborn boys and prepubertal boys

BACKGROUND/AIM

Responsiveness to GH in target cells is mediated by its receptor, which activates the Janus kinase-2 (JAK2) and STAT5 (signal transducers and activators of transcription 5) leading to the expression of IGF-1 and IGFALS. The aim of this study was to compare the GH signaling pathway in newborns and prepubertal boys.

SUBJECTS AND METHODS

We determined the GHR protein content and the effect of stimulation with recombinant human GH (rhGH; 200ng/mL) on JAK2 and STAT5 phosphorylation in skin fibroblast cultures obtained from newborns and prepubertal boys. The transcript levels of IGFALS and IGF-I, were also studied and compared after 16h or 24h of stimulation with GH in both study groups.

RESULTS

Newborn infants showed less GHR protein than the prepubertal boys. After rhGH stimulation, JAK2 and STAT5 phosphorylation was absent in skin fibroblasts from newborns, but was clearly detectable in prepubertal boys. After 16h of treatment with rhGH, IGFALS and IGF-I transcript levels increased in the prepubertal boys when compared to baseline. In newborns, however, we did not observe a response after 16 and 24h of rhGH stimulation.

CONCLUSION

The significant attenuation of the GH signaling pathway observed in fibroblasts from newborn boys appears to be related to a reduction in GHR content and lack of phosphorylation of JAK2 and STAT5 in response to rhGH. This might impair STAT5 dimer formation, leading to a reduction in the transcript levels of IGFALS and IGF-I during the newborn period.

IGF-I at 9 and 36 months of age — relations with body composition and diet at 3 years — the SKOT cohort

OBJECTIVE

High infancy levels of insulin-like growth factor-I (IGF-I) have been associated with increased linear growth and fat-free mass (FFM) but also with risk of obesity. This paper examines how IGF-I at 9 and 36 months relates to diet and body composition.

DESIGN

Healthy term infants from the prospective cohort study, SKOT, were examined at 9 and 36 months with anthropometry, bioelectrical impedance (36 months), 7-day food records and blood analysis of IGF-I and IGFBP-3 by chemiluminescent immunometric assay.

RESULTS

IGF-I at 36 months (n = 229) was positively correlated with 9 months values and values were considerably higher in girls (43%). Children breastfed at 9 months had lower IGF-I concentrations at 9 months but reached the same IGF-I concentrations at 36 months as infants not breastfed at 9 months. IGF-I at 36 months was positively associated with height, weight, BMI, predicted FFM and FFM index (FFM/height (kg/m2)). Although there also was a positive association with predicted fat mass (FM) there was no association with FM index (FM/height (kg/m2)). Further, a negative association with skin fold thickness was observed. A change in IGF-I from 9–36 months was positively related to FFM and FFM index but not BMI, FM and FM index. No associations were seen between IGF-I and current intake of milk, meat or protein energy percentage, but both fat and saturated fat energy percentage were negatively associated with IGF-I.

CONCLUSION

IGF-I concentrations were positively associated with growth but not with adiposity at this age. However, the higher tempo of growth may influence age at adiposity rebound and thereby later risk of obesity. Milk and protein intake at 36 months did not influence IGF-I but there was a negative association with intake of fat and saturated fat. The implications of this finding for development of obesity need further exploration.

Early nutrition impact on the insulin-like growth factor axis and later health consequences

PURPOSE OF REVIEW

There is increasing interest in the role of insulin-like growth factor-I (IGF-I) in the relation between early growth and later risk of noncommunicable diseases (NCDs). This review presents and discusses a selection of recent publications on this topic.

RECENT FINDINGS

Nutrition during pregnancy and in preterm infants has an influence on IGF-I. Breastfeeding is associated with lower IGF-I values and the effect of early protein intake was confirmed in a large intervention study. IGF-I levels are associated with early obesity, but the relation is complex and differs with age. Further studies and reviews support that there is a programming of the IGF axis, with higher levels during early life being associated with lower levels in adulthood, which is likely to influence the risk of NCDs later in life.

SUMMARY

Recent studies support that IGF-I plays an important role in the complex association between early diet, growth and later health, but more studies are needed to better understand the role of IGF-I, especially in the early development of obesity. Studies with data on how IGF-I is influenced by early diet in studies of preterm infants and young children with undernutrition from low-income countries will be helpful in recommending optimal diets.