Endocrine disorders in childhood and adolescence. Natural history of subclinical hypothyroidism in children and adolescents and potential effects of replacement therapy: a review.

OBJECTIVE: Subclinical hypothyroidism (SH) is quite common in children and adolescents. The natural history of this condition and the potential effects of replacement therapy need to be known to properly manage SH. The aim of this review is to analyse: 1) the spontaneous evolution of SH, in terms of the rate of reversion to euthyroidism the persistence of SH or the progression to over hypothyroidism; 2) the effects of replacement therapy, with respects to auxological data, thyroid volume and neuropsychological functions. Methods: We systematically searched PubMed, Cochrane and EMBASE (1990 to 2012) and identified 39 potentially relevant articles of which only 15 articles were suitable to be included. Results and Conclusions: SH in children is a remitting process with a low risk of evolution toward overt hypothyroidism. Most of the subjects reverted to euthyroidism or remained SH, with a rate of evolution toward overt hypothyroidism ranging between 0% to 28.8%, being 50% in only one study (9 articles). The initial presence of goiter and elevated thyroglobulin-antibodies, the presence of coeliac disease and a progressive increase in thyroperoxidase-antibodies and TSH value predict a progression toward overt hypothyroidism. Replacement therapy is not justified in children with SH but with TSH 5-10 mIU/L, no goiter and negative anti-thyroid antibodies. An increased growth velocity was shown in children treated with levothyroxine (2 articles). Levothyroxine reduced thyroid volume in 25% to 100% of children with SH and autoimmune thyroiditis (2 studies). No effects on neuropsychological functions (one study) and post-treatment evolution of SH (one study) were reported

Effect of Arginine Infusion on Ghrelin Secretion in Growth Hormone-Sufficient and GH-Deficient Children.

Background: The physiological link between ghrelin and growth hormone (GH) has not yet been fully clarified. Furthermore, the existence of a negative feedback mechanism between growth hormone\u2013insulin-like growth factor (GH\u2013IGF)-I axis and ghrelin and the influence of amino acids on ghrelin secretion in children remain matters of debate. Objectives: To understand the regulation of ghrelin secretion and clarify the relationship between ghrelin and GH secretion in GH-deficient (GHD) and GH-sufficient (GHS) children Patients and Methods: Ten GHD (male/female [M/F], 6/4; age [mean \ub1 SEM], 10.7 \ub1 0.9 years) and 10 GHS prepubertal children (M/F, 6/4; age [mean \ub1 SEM], 10.3 \ub1 0.6 years), underwent an arginine (ARG) test (infusion, 0.5 g/kg, iv). Levels of GH, total ghrelin, and acylated ghrelin (AG) were assayed every 30 min from 0 to +120 min. Results: Peak GH values were lower in GHD subjects than in GHS subjects (P < 0.0001). The baseline levels, peak levels, or area under the curves (AUC) for total ghrelin and AG were similar between GHD and GHS children. ARG infusion was followed by a slight to significant decrease in total ghrelin levels, but not AG levels, both in GHD and GHS subjects with a nadir at +30 min. No correlation was seen between GH, total ghrelin, or AG response and ARG infusion. Conclusions: Total ghrelin and AG levels seemed unaffected by GH status in prepubertal children. ARG infusion was unable to blunt ghrelin secretion irrespective of GH status in childhood. Moreover, since ARG influences GH secretion via modulation of somatostatin release, ghrelin secretion seems to be partially refractory to somatostatin action

High-end normal adrenocorticotropic hormone and cortisol levels are associated with specific cardiovascular risk factors in pediatric obesity: a cross-sectional study.

BACKGROUND: The hypothalamic-pituitary-adrenal (HPA) axis, and in particular cortisol, has been reported to be involved in obesity-associated metabolic disturbances in adults and in selected populations of adolescents. The aim of this study was to investigate the association between morning adrenocorticotropic hormone (ACTH) and cortisol levels and cardiovascular risk factors in overweight or obese Caucasian children and adolescents. METHODS: This cross-sectional study of 450 obese children and adolescents (aged 4 to 18 years) was performed in a tertiary referral center. ACTH, cortisol, cardiovascular risk factors (fasting and post-challenge glucose, high-density lipoprotein (HDL)-cholesterol, low-density lipoprotein (LDL)-cholesterol, triglycerides, and hypertension) and insulin resistance were evaluated. All analyses were corrected for confounding factors (sex, age, puberty, body mass index), and odds ratios were determined. RESULTS: ACTH and cortisol levels were positively associated with systolic and diastolic blood pressure, triglycerides, fasting glucose and insulin resistance. Cortisol, but not ACTH, was also positively associated with LDL-cholesterol. When adjusted for confounding factors, an association between ACTH and 2 h post-oral glucose tolerance test glucose was revealed. After stratification according to cardiovascular risk factors and adjustment for possible confounding factors, ACTH levels were significantly higher in subjects with triglycerides 6590th percentile (P 5.92 pmol/l) and cortisol (>383.5 nmol/l) although within the normal range were associated with increases in cardiovascular risk factors in this population. CONCLUSIONS: In obese children and adolescents, high morning ACTH and cortisol levels are associated with cardiovascular risk factors. High ACTH levels are associated with high triglyceride levels and hyperglycemia, while high cortisol is associated with hypertension and high LDL-cholesterol. These specific relationships suggest complex mechanisms through which the HPA axis may contribute to metabolic impairments in obesity, and merit further investigations