The endocrinology of adolescence

Impact of metabolic syndrome and its components on bone remodeling in adolescents

INTRODUCTION

Osteoporosis and metabolic syndrome (MetS) are diseases that have serious public health consequences, reducing the quality of life of patients and increasing morbidity and mortality, with substantial healthcare expenditures.

OBJECTIVE

To evaluate the impact of MetS on bone mineral density (BMD) and biochemical markers of bone formation and resorption in adolescents with excess weight.

METHOD

A descriptive and analytical cross-sectional study was performed that evaluated 271 adolescents of both sexes (10 to 16 years). From the total sample, 42 adolescents with excess weight and the presence of MetS (14%) were selected. A further 42 adolescents with excess weight and without MetS were chosen, matched for chronological age, bone age, and pubertal developmental criteria to those with MetS, for each sex. Anthropometric measurements, blood pressure collection, and biochemical tests were performed in all adolescents, as well as evaluation of BMD and the bone biomarkers osteocalcin (OC), bone alkaline phosphatase (BAP), and carboxy-terminal telopeptide (S-CTx).

RESULTS

The adolescents with excess weight and MetS exhibited significantly lower transformed BMD and concentrations of BAP, OC, and S-CTx compared to the matched group, except for OC in boys. A negative and significant correlation was observed between total body BMD and BAP (r = -0.55568; p = 0.005), OC (r = -0.81760; p = < .000), and S-CTx (r = -0.53838; p = 0.011) in girls.

CONCLUSION

Metabolic syndrome may be associated with reduced bone mineral density and biochemical markers of bone formation and resorption in adolescents with excess weight.

Low-dose combined oral contraceptive use is associated with lower bone mineral content variation in adolescents over a 1-year period

BACKGROUND

Low-dose combined oral contraceptives (COCs) can interfere with bone mass acquisition during adolescence. This study aimed to evaluate bone mineral density (BMD) and bone mineral content (BMC) in female adolescents taking a standard low-dose COC (ethinylestradiol 20 μg/desogestrel 150 μg) over a 1-year period and to compare their data with those of healthy adolescents from the same age group not taking COCs.

METHODS

This was a non-randomized parallel-control study with a 1-year follow-up. Sixty-seven adolescents aged from 12 to 19 years, divided into COC users (n = 41) taking 20 μg ethinylestradiol/150 μg desogestrel and COC non-user controls (n = 26), were evaluated by bone densitometry examinations at baseline and after 12 months. Comparisons between the groups at the study onset were performed using the Mann-Whitney test with the significance level fixed at 5% or p < 0.05. Comparisons between the groups at the study onset and after 12 months were based on variations in the median percentages for bone mass variables.

RESULTS

The COC users presented with low bone mass acquisition in the lumbar spine, and had BMD and BMC median variations of 2.07% and +1.57%, respectively, between the measurements at baseline and 12 months. The control group had median variations of +12.16% and +16.84% for BMD and BMC, respectively, over the same period. The total body BMD and BMC showed similar evolutions during the study in both groups. Statistical significance (p < 0.05) was seen for the BMC percentage variation between COC users and non-users.

CONCLUSIONS

Use of a low-dose COC (ethinylestradiol 20 μg/desogestrel 150 μg) was associated with lower bone mass acquisition in adolescents during the study period.

TRIAL REGISTRATION

Registry Number, RBR-5h9b3c.

Hormonal regulation of hepatic drug-metabolizing enzyme activity during adolescence

Activities of drug-metabolizing enzymes (DMEs) are known to change throughout the course of physical and sexual maturation, with the greatest variability noted during infancy and adolescence. The mechanisms responsible for developmental regulation of DME are currently unknown. However, the hormonal changes associated with puberty/adolescence provide a theoretical framework for understanding the biochemical regulation of DME activity during growth and maturation. Important information regarding potential influences of growth and sex hormones can also be extrapolated from studies that evaluate changes in activities of DMEs occurring as a consequence of physiological, pathological, and/or pharmacological hormonal fluctuations. Collectively, current data support the hypothesis that isoform-specific alterations in DME activity during adolescence are mediated by sex and/or growth hormones. Characterization of the underlying biochemical alterations responsible for developmental changes in DME activity will require additional studies in which relationships between DMEs and important hormonal axes are evaluated during the course of pubertal development.

Memory of insulin pumps and their record as a source of information about insulin therapy in children and adolescents with type 1 diabetes

BACKGROUND

This study was designed to provide information regarding basal and bolus insulin dosage in children and adolescents using continuous subcutaneous insulin infusion (CSII) and to evaluate the safety and efficacy of the CSII method in youths.

PATIENTS AND METHODS

Data from 100 patients (1.6-18 years old) were collected during scheduled visits in an outpatient clinic. The mean duration of diabetes was 4.57 years (range 0.6-16 years), and mean duration of CSII therapy was 1.75 years (range 0.5-3.0 years). Each child had his or her insulin doses reviewed using the Medtronic MiniMed (Northridge, CA) Pumps&Meters software program. At each visit glycosylated hemoglobin (HbA1c) values and growth parameters (weight and height) were assessed, and episodes of severe hypoglycemia and ketoacidosis were recorded.

RESULTS

The mean HbA1c value in our study group was 7.63 +/- 0.09% (range, 5.15-12.5%). Statistically significant better metabolic control was found in children under 10 years of age, in children with lower body mass index (r = 0.33), in patients with a lower contribution of basal insulin to the total daily dose (r = 0.35; P < 0.05), and in boys. Ten percent of participants skipped mealtime boluses, which correlated with their glycemic control; in those children HbA1c was 8.67 +/- 0.57% (r = 0.34; P < 0.05). The mean total daily insulin was 0.79 +/- 0.02 U/kg/day (range, 0.3-2.0 U/kg/day). Basal insulin constituted on average 35.6 +/- 1.1% (5-70%) of the daily insulin dose. We found a statistically significant higher contribution of basal insulin dose in patients who missed mealtime boluses (r = 0.42; P < 0.05) and a significantly lower contribution in pre-pubertal children and in boys (P < 0.05). Around 7% of patients made mistakes in programming the basal insulin.

CONCLUSIONS

CSII may be safely and efficiently used in children with type 1 diabetes in different age groups. This method of treatment requires regular visits to an outpatient clinic, proper education, and frequent revisions of the pump's memory.

Growth at puberty

Somatic growth and maturation are influenced by a number of factors that act independently or in concert to modify an individual's genetic potential. The secular trend in height and adolescent development is further evidence for the significant influence of environmental factors on an individual's genetic potential for linear growth. Nutrition, including energy and specific nutrient intake, is a major determinant of growth. Paramount to normal growth is the general health and well-being of an individual; in fact, normal growth is a strong testament to the overall good health of a child. More recently the effect of physical activity and fitness on linear growth, especially among teenage athletes, has become a topic of interest. Puberty is a dynamic period of development marked by rapid changes in body size, shape, and composition, all of which are sexually dimorphic. One of the hallmarks of puberty is the adolescent growth spurt. Body compositional changes, including the regional distribution of body fat, are especially large during the pubertal transition and markedly sexually dimorphic. The hormonal regulation of the growth spurt and the alterations in body composition depend on the release of the gonadotropins, leptin, the sex-steroids, and growth hormone. It is very likely that interactions among these hormonal axes are more important than their main effects, and that alterations in body composition and the regional distribution of body fat actually are signals to alter the neuroendocrine and peripheral hormone axes. These processes are merely magnified during pubertal development but likely are pivotal all along the way from fetal growth to the aging process.

Serum dehydroepiandrosterone sulphate and pubertal development in Chinese girls

Serum dehydroepiandrosterone sulphate (DHEAS), estradiol (E2), luteinizing hormone (LH) and follicle stimulating hormone (FSH) were measured by radioimmunoassay in 170 healthy school girls from 7-16 years old. Blood samples from postmenarcheal girls were taken on days 6-10 of the menstrual cycle. Bone age, height, weight, breast and pubic hair development were also investigated. Of the four hormones measured, serum DHEAS displayed the earliest elevation, at 7 years and upwards. A significant DHEAS increment at chronological age 13 years was observed. Girls with earlier menarche had higher DHEAS level than girls having later menarche. Serum DHEAS levels also correlated with bone age, height, weight, subcutaneous fat and pubertal stages. The results suggest that adrenal androgen might be involved in the initiation of puberty and female maturation.

Biosocial foundations for adolescent female sexuality

Despite the widespread assumption that hormones stimulate motivation for sexual behavior in adolescence, no published empirical studies have demonstrated this link. In a cross-sectional study of 78 females in the eighth, ninth, and tenth grades in public schools, we show that hormones have effects on sexual motivation and behavior. Comparison with previous results from a parallel sample of males indicates that for both sexes these effects are primarily androgenic in origin and for the most part exert their effects directly rather than through the social interpretation of age and hormone-induced pubertal development.

A comparative study of the effect of oestrogen substitution therapy on breast development in girls with hypo- and hypergonadotrophic hypogonadism

During treatment of girls with oestrogen deficiency we observed different patterns of breast development in response to therapy. The forty-five girls studied fell into four groups: Group A, gonadal dysgenesis; Group B, isolated gonadotrophin deficiency; Group C, multiple pituitary hormone deficiencies; Group D, congenital adrenal hyperplasia (17-alpha-hydroxylase deficiency). Treatment with oestrogen was given in an identical manner to all. In the patients with gonadal dysgenesis, in whom the hypothalamic-pituitary function was normal, treatment led to full breast development. In isolated gonadotrophin deficiency and multiple pituitary hormone deficiency breast development was incomplete even after 3 years or more of oestrogen treatment. The conspicuous difference in the hormonal status is that the latter two groups lack gonadotrophins, while in gonadal dysgenesis these hormones are grossly elevated. Our conclusion is that gonadotrophins play an important role in mammary gland development, a finding not previously described. In the girl with 17-alpha-hydroxylase deficiency we observed that cortisol was necessary, in addition to sex hormones, for normal breast development.