Age of puberty among girls and the diagnosis of precocious puberty

Delayed Puberty-Phenotypic Diversity, Molecular Genetic Mechanisms, and Recent Discoveries

This review presents a comprehensive discussion of the clinical condition of delayed puberty, a common presentation to the pediatric endocrinologist, which may present both diagnostic and prognostic challenges. Our understanding of the genetic control of pubertal timing has advanced thanks to active investigation in this field over the last two decades, but it remains in large part a fascinating and mysterious conundrum. The phenotype of delayed puberty is associated with adult health risks and common etiologies, and there is evidence for polygenic control of pubertal timing in the general population, sex-specificity, and epigenetic modulation. Moreover, much has been learned from comprehension of monogenic and digenic etiologies of pubertal delay and associated disorders and, in recent years, knowledge of oligogenic inheritance in conditions of GnRH deficiency. Recently there have been several novel discoveries in the field of self-limited delayed puberty, encompassing exciting developments linking this condition to both GnRH neuronal biology and metabolism and body mass. These data together highlight the fascinating heterogeneity of disorders underlying this phenotype and point to areas of future research where impactful developments can be made.

Adolescence: what do transmission, transition, and translation have to do with it?

Negotiating the transition from dependence on parents to relative independence is not a unique demand for today's youth but has a long evolutionary history (transmission) and is shared across mammalian species (translation). However, behavioral changes observed during this period are often described as delinquent. This review examines changes in explorative and emotive behaviors during the transition into and out of adolescence and the underlying neurobiological bases in the context of adaptive and maladaptive functions.

Salivary progesterone levels before menarche: a prospective study of adolescent girls

OBJECTIVE

Our objective was to determine the frequency of ovulatory salivary progesterone levels before menarche in healthy girls.

DESIGN

We recruited a prospective cohort of midpubertal, premenarcheal girls. Participants collected weekly saliva samples until first menses or for 12 months. Menstrual cycles were considered to have ovulatory salivary progesterone levels if values were greater than 0.100 ng/ml (0.318 nmol/liter) 0-14 d before menarche.

SETTINGS

Participants collected saliva samples weekly at home and attended monthly clinic visits.

PATIENTS

Patients included 63 premenarcheal females, age 9-15 yr, with body mass index higher than the fifth percentile for age and Tanner stage III or greater for both pubic hair and breast development.

MAIN OUTCOME MEASURES

Frequency of ovulatory levels of salivary progesterone before menarche was assessed.

RESULTS

Fifty-five girls completed the study, and 43 experienced menarche. Of the 42 girls who reached menarche and provided a sample within 14 d of menarche, five (12%) had ovulatory progesterone levels. The mean anovulatory salivary progesterone level was 0.041 ng/ml (0.130 nmol/liter; range, 0.012-0.078 ng/ml, 0.038-0.248 nmol/liter), and the mean ovulatory level was 0.194 ng/ml (0.617 nmol/liter; range, 0.125-0.343 ng/ml, 0.398-1.09 nmol/liter). The levels of estrogen, testosterone, and 17-hydroxyprogesterone were higher and the mean BMI was lower in those with ovulatory progesterone levels vs. those with anovulatory levels.

CONCLUSION

A significant proportion of girls displayed ovulatory levels of progesterone before menarche. More research is needed to clarify the hormonal events that occur in the perimenarcheal time period.

El tratamiento con triptorelina en las niñas con pubertad precoz central provoca incremento del índice de masa corporal

INTRODUCTION

The most important complications of central precocious puberty (CPP) in girls are loss of height and multiple psychosocial problems.

OBJECTIVES

To study the effect of triptorelin therapy in a cohort of girls with CPP.

PATIENTS AND METHODS

Thirty-four girls diagnosed with organic or idiopathic CPP and treated with monthly triptorelin were studied. Age, height in standard deviation (SD), bone age (Greulich and Pyle), height prediction (Bayle-Pinneau), body mass index (BMI) in SD, uterine size (pelvic ultrasound), target height, cranial magnetic resonance imaging, triptorelin dose, and treatment duration were studied.

RESULTS

Triptorelin produced a statistically significant reduction in growth velocity and an increase in BMI after 1 year of therapy and these changes were maintained after discontinuation of therapy. Adult height in these patients was in accordance with their target genetic height, as well as with their predicted height according to the method of Bayley-Pinneau. No significant differences were found between age of menarche in our patients and in controls. Adult height in patients with organic CPP was significantly lower than that in patients with idiopathic CPP.

CONCLUSIONS

1. Triptorelin can increase BMI in girls with CPP. 2. The presence of an organic cause in patients with CPP worsens the prognosis for adult height. 3. The Bayley-Pinneau prediction method for "average" bone age is useful for establishing a prognosis of adult height in girls with CPP treated with triptorelin.

Lifetime changes in the vulva and vagina

The morphology and physiology of the vulva and vagina change over a lifetime. The most salient changes are linked to puberty, the menstrual cycle, pregnancy, and menopause. The cutaneous epithelia of the mons pubis, labia, and clitoris originate from the embryonic ectoderm and exhibit a keratinized, stratified structure similar to the skin at other sites. The mucosa of the vulvar vestibule, which originates from the embryonic endoderm, is non-keratinized. The vagina, derived from the embryonic mesoderm, is responsive to estrogen cycling. At birth, the vulva and vagina exhibit the effects of residual maternal estrogens. During puberty, the vulva and vagina acquire mature characteristics in a sequential fashion in response to adrenal and gonadal maturation. A trend to earlier pubertal onset has been observed in Western developed countries. In women of reproductive age, the vaginal mucosa responds to steroid hormone cycling, exhibiting maximal thickness and intracellular glycogen content at mid-cycle. Vulvar skin thickness remains unchanged but menstrual cycle-associated changes in ortho- and parakeratosis occur at the cytological level. The vulva and vagina further adapt to the needs of pregnancy and delivery. After menopause, tissue atrophy ensues. Post-menopausal changes in skin barrier function, skin hydration, and irritant susceptibility have been observed on exposed skin but not on the vulva. Nevertheless, older women with incontinence are at increased risk for developing incontinence dermatitis. A combination of factors, such as tissue atrophy, slower dissipation of excess skin hydration, shear forces associated with limited mobility, and lower tissue regeneration capacity increase the risk of morbidity from incontinence dermatitis in older women.

Long-term growth and puberty concerns in international adoptees

Growth delay is one of the most common and persistent findings in children who have been adopted from abroad. Although the cause is not clearly understood, it may be related to the observed phenomenon of psychosocial short stature described in children from abusive and neglectful settings in western countries. Fortunately, adopted children generally experience significant improvement in growth after joining their new family, but this may put girls at risk for early and rapidly progressing puberty. This review should help the health care team to understand these issues and work better with the adoptive parents to ensure a child's smooth transition into family life.

Regulation and disorders of pubertal timing

Disorders of pubertal timing are common and challenging problems for pediatric endocrinologists. Early or late puberty can have immediate effects on a child's psychosocial well-being and may have long-term effects on adult stature. Much is known about the regulation of the hypothalamic-pituitary-gonadal axis, but the triggers of pubertal onset in the general population remain elusive. This article reviews recent data suggesting a possible shift in the age of pubertal onset; current knowledge regarding factors that regulate the onset of puberty; and the etiologies, diagnosis, and treatment of precocious and delayed puberty.

The timing of normal puberty and the age limits of sexual precocity: variations around the world, secular trends, and changes after migration

During the past decade, possible advancement in timing of puberty has been reported in the United States. In addition, early pubertal development and an increased incidence of sexual precocity have been noticed in children, primarily girls, migrating for foreign adoption in several Western European countries. These observations are raising the issues of current differences and secular trends in timing of puberty in relation to ethnic, geographical, and socioeconomic background. None of these factors provide an unequivocal explanation for the earlier onset of puberty seen in the United States. In the formerly deprived migrating children, refeeding and catch-up growth may prime maturation. However, precocious puberty is seen also in some nondeprived migrating children. Attention has been paid to the changing milieu after migration, and recently, the possible role of endocrine- disrupting chemicals from the environment has been considered. These observations urge further study of the onset of puberty as a possible sensitive and early marker of the interactions between environmental conditions and genetic susceptibility that can influence physiological and pathological processes.

Relative weight and race influence average age at menarche: results from two nationally representative surveys of US girls studied 25 years apart

OBJECTIVES

1) To establish with nationally representative US data whether menarche occurred earlier in the 1990s than it had 25 years before. 2) To assess whether the occurrence of menarche in relation to weight status and race had changed over this time period.

METHODS

Relative weight, race, and menarcheal status of girls in the National Health Examination Survey cycles II and III (1963-1970) were compared with results from the Third National Health and Nutrition Examination Survey (1988-1994). Probit analysis was used to determine the average age at menarche during the 2 survey periods. Logistic regression was used to assess the association of relative weight to likelihood of having reached menarche.

RESULTS

The average age at menarche dropped from 12.75 to 12.54 years, and the percentage of girls between 10 and 15 years old who were above the 85th percentile for body mass index increased from 16% to 27% over the 25 years between the 2 surveys. Higher relative weight was strongly associated with increased likelihood of having reached menarche after controlling for age and race. Black girls had a lower average age at menarche than did white girls, which was independent of the effect of relative weight.

CONCLUSIONS

These analyses from 2 nationally representative samples of US girls suggest a drop of about 2(1/2) months in the average age of menarche during the time period between 1963-1970 and 1988-1994. This was paralleled by a concurrent shift in the population distribution of body mass index z-score toward higher relative weights.

Age at menarche and racial comparisons in US girls

BACKGROUND

Concern regarding change in the onset of sexual maturation of US girls has increased the need for current information on age at menarche from a national sample. Previous reports have been sparse and interpretation has been limited because of the racial composition and ages of the samples.

OBJECTIVE

The objectives of this study were to estimate the distribution of age at menarche for all US girls and for non-Hispanic white, black, and Mexican American girls in the Third National Health and Nutrition Examination Survey and to test for racial differences.

DESIGN

Menstrual status data were collected from 2510 girls aged 8.0 to 20.0 years. The Third National Health and Nutrition Examination Survey followed a complex, stratified, multistage probability cluster design. SUDAAN was used to calculate proportions of girls reaching menarche at an age. Ages at menarche were estimated by probit analysis at the ages at which 10%, 25%, 50%, 75%, and 90% of the girls attained menarche.

RESULTS

Less than 10% of US girls start to menstruate before 11 years, and 90% of all US girls are menstruating by 13.75 years of age, with a median age of 12.43 years. This age at menarche is not significantly different (0.34 years earlier) than that reported for US girls in 1973. Age at menarche for non-Hispanic black girls was significantly earlier than that of white girls at 10%, 25%, and 50% of those who had attained menarche, whereas Mexican American girls were only significantly earlier than the white girls at 25%.

CONCLUSION

Overall, US girls are not gaining reproductive potential earlier than in the past. The age at menarche of non-Hispanic black girls is significantly earlier than that of non-Hispanic white and Mexican American girls.

National estimates of the timing of sexual maturation and racial differences among US children

OBJECTIVE

To provide clinically meaningful, normative reference data that describe the timing of sexual maturity indicators among a national sample of US children and to determine the degree of racial/ethnic differences in these estimates for each maturity indicator.

METHODS

Tanner staging assessment of sexual maturity indicators was recorded from 4263 non-Hispanic white, black, and Mexican American girls and boys aged 8.00 to 19.00 years as part of the Third National Health and Nutrition Examination Survey (NHANES III) conducted between 1988 and 1994. NHANES III followed a complex, stratified, multistage probability cluster design. SUDAAN was used to calculate the mean age and standard error for each maturity stage and the proportion of entry into a maturity stage and to incorporate the sampling weight and design effects of the NHANES III complex sampling design. Probit analysis and median age at entry into a maturity stage and its fiducial limits were calculated using SAS 8.2.

RESULTS

Reference data for age at entry for maturity stages are presented in tabular and graphical format. Non-Hispanic black girls had an earlier sexual development for pubic hair and breast development either by median age at entry for a stage or for the mean age for a stage than Mexican American or non-Hispanic white girls. There were few to no significant differences between the Mexican American and non-Hispanic white girls. Non-Hispanic black boys also had earlier median and mean ages for sexual maturity stages than the non-Hispanic white and Mexican American boys.

CONCLUSION

Non-Hispanic black girls and boys mature early, but US children completed their sexual development at approximately the same ages. The present reference data for the timing of sexual maturation are recommended for the interpretation of assessments of sexual maturity in US children.

The missing politics and unsettled science of the trend toward earlier puberty

The age of puberty in many populations has declined steeply over recent centuries and may be declining still. Consequently, today's children tend to experience the hormonal stresses of rapid development at younger ages than did their ancestors, around whose later, if not more gradual, maturation traditional behavioral expectations formed. Little has been made of this "rush to puberty" outside the life sciences. This article reviews its historical documentation, scholarly appreciation, epidemiological correlations, putative physiological and environmental explanations, sociological implications, and largely latent politics.