Longitudinal association of prepubertal urinary phthalate metabolite concentrations with pubertal progression among a cohort of boys

BACKGROUND

Epidemiological studies have reported associations of anti-androgenic phthalate metabolite concentrations with later onset of male puberty, but few have assessed associations with progression.

OBJECTIVES

We examined the association of prepubertal urinary phthalate metabolite concentrations with trajectories of pubertal progression among Russian boys.

METHODS

At enrollment (ages 8-9 years), medical history, dietary, and demographic information were collected. At entry and annually to age 19 years, physical examinations including testicular volume (TV) were performed and spot urines collected. Each boy's prepubertal urine samples were pooled, and 15 phthalate metabolites were quantified by isotope dilution LC-MS/MS at Moscow State University. Metabolites of anti-androgenic parent phthalates were included: butylbenzyl (BBzP), di-n-butyl (DnBP), diisobutyl (DiBP), di(2-ethylhexyl) (DEHP) and diisononyl (DiNP) phthalates. We calculated the molar sums of DEHP, DiNP, and all AAP metabolites. We used group-based trajectory models (GBTMs) to identify subgroups of boys who followed similar pubertal trajectories from ages 8-19 years based on annual TV. We used multinomial and ordinal regression models to evaluate whether prepubertal log-transformed phthalate metabolite concentrations were associated with slower or faster pubertal progression trajectories, adjusting for covariates.

RESULTS

304 boys contributed a total of 752 prepubertal urine samples (median 2, range: 1-6) for creation of individual pools. The median length of follow-up was 10.0 years; 79% of boys were followed beyond age 15. We identified three pubertal progression groups: slower (34%), moderate (43%), and faster (23%) progression. A standard deviation increase in urinary log-monobenzyl phthalate (MBzP) concentrations was associated with higher adjusted odds of being in the slow versus faster pubertal progression trajectory (aOR 1.47, 95% CI 1.06-2.04). None of the other phthalate metabolites were associated with pubertal progression.

CONCLUSIONS

On average, boys with higher concentrations of prepubertal urinary MBzP had a slower tempo of pubertal progression, perhaps attributable to the disruption of androgen-dependent biological pathways.

Associations of prepubertal urinary phthalate metabolite concentrations with pubertal onset among a longitudinal cohort of boys

BACKGROUND

Although phthalate exposures have been associated with adverse effects on male reproductive health, few studies have explored longitudinal associations with male pubertal development.

OBJECTIVES

We examined the association of prepubertal urinary concentrations of phthalate metabolites with age at pubertal onset in a prospective cohort of Russian boys.

METHODS

At enrollment at ages 8-9 years, medical history, dietary, and demographic information was collected. At entry and annually, physical examinations and pubertal staging [Genitalia (G), Pubarche (P), and testicular volume (TV, in ml)] were conducted and spot urines were collected. Prepubertal urine samples (defined as either TV = 1, 2 and G = 1, 2 or TV = 3 and G = 1) were pooled for each boy and phthalate metabolite concentrations were quantified using isotope dilution LC-MS/MS at Moscow State University. We measured 15 metabolites including those from anti-androgenic parent phthalates (AAPs) such as di (2-ethylhexyl) (DEHP) and di-isononyl (DiNP) phthalates as well as monobenzyl (MBzP), mono-n-butyl (MnBP), and mono-isobutyl (MiBP) metabolites. We calculated the molar sums of DEHP (∑DEHP), DiNP (∑DiNP), and AAP (∑AAP) metabolites. Separate interval-censored models were used to assess associations of quartiles of prepubertal phthalate metabolites with each pubertal onset indicator, G2+, P2+ and TV > 3 mL, adjusted for covariates and urine specific gravity.

RESULTS

304 boys had 752 prepubertal urine samples (median 2, range: 1-6) for pooling. In adjusted models, higher urinary AAPs were consistently associated with later pubertal onset (P2) with mean shifts ranging from 8.4 to 14.2 months for the highest versus lowest quartiles. Significantly later onset for G2 and TV > 3 mL was observed for higher versus lower quartiles of MiBP, MBzP, ∑DEHP and ∑DiNP.

CONCLUSIONS

On average, boys with higher concentrations of prepubertal urinary AAPs had later pubertal onset by six months to over a year. The impact of AAPs on timing of male puberty may be attributable to disruption of androgen-dependent biological pathways.

Update on pubertal development in France. PROSPEL - Observational study. Preliminary feasibility study

INTRODUCTION

Recent publications report a decrease in the age of onset of pubertal changes in the United States and Europe. The PROSPEL study (PRemier Observatoire des Stades Pubertaire en Libéral) will provide the first French data on the age at which pubertal signs appear. Before considering this work at the national level, we wanted to assess its feasibility.

MATERIALS AND METHODS

Private pediatricians and general practitioners were recruited in Bordeaux and Toulouse. Before participating in the study, they had been trained in pubertal assessment and then evaluated. Each physician completed 1-4 weeks of inclusion during which children aged 5-18 years seen in consultation were included, except children who were adopted or had a chronic condition. Pubertal stages were assessed according to Tanner's classification and using an orchidometer for testicular volume. The causes of non-realization were documented where appropriate. Inter-individual reproducibility was analyzed by a double examination for a number of children who had previously given their consent.

RESULTS

In total, 63 physicians participated in the study (35 pediatricians and 28 general practitioners). All were certified at the end of the training session. A total of 2646 children were included (1318 girls, 1328 boys) with a homogeneous age distribution. The study was carried out in 83.5% of cases. The main reason for non-realization was that physicians did not propose the study to patients who met the criteria (10.1%). Lack of time was the main reason. Inter-individual reproducibility was excellent.

DISCUSSION AND CONCLUSION

Our results attest to the good feasibility of the PROSPEL study. They allowed us to validate our methodology, the training and certification of the participating physicians, and to consider extending the study to the national level.

Pubertal assessment: targeted educational intervention for pediatric trainees

Background Timely and periodic pubertal assessment in children is vital to identify puberty related disorders. Pediatricians need to have working knowledge of puberty time and tempo. Pediatric residency is an important platform to acquire physical examination skills including pubertal assessment. Objective An educational intervention for teaching pubertal assessment was piloted on pediatric residents at our institution. Methods The intervention comprised of interactive lecture series, ID badge size Tanner stage cards and Tanner posters placed in residents' continuity clinics. Pre-intervention, post-intervention and 3 months post-intervention surveys for participating trainees were administered to determine the effectiveness of the intervention. Attitudes, practices, knowledge scores, and barriers to Tanner staging conduct were analyzed. Results Forty-three residents participated in the intervention. Knowledge scores of PGY1 (5.95 ± 1.6 vs. 7.47 ± 1.4, p < 0.01) improved right after the intervention, as did self-reported clinical practices of all trainees 3 months post- intervention with regards to conducting external genital examination and performing pubertal assessment. Confidence levels of pediatric trainees in conducting pubertal assessment and comfort levels in assessing the need for endocrine referral based on abnormal Tanner staging improved after the intervention, although the effect was not statistically significant. Conclusion Our intervention is a worthwhile technique for teaching pubertal assessment to residents as it is simple to conduct, easily reproducible, provides baseline knowledge needed for recognition of normal pubertal development and puberty related conditions, and instills confidence in residents.

Development of an Online Learning Module to Improve Pediatric Residents' Confidence and Knowledge of the Pubertal Examination

PURPOSE

Pediatric residents must know how to perform pubertal examinations. The initial objective of this study was to evaluate pediatric resident knowledge and comfort related to the pubertal examination and to determine whether and why these examinations are avoided. The subsequent objective was to develop and assess a learning module (LM) addressing identified education gaps.

METHODS

A learning needs assessment (LNA) was administered to residents in four Canadian pediatric training programs. Identified themes and knowledge gaps were used to develop an online, case-based LM. A randomized assessment of the LM was conducted among residents from nine training programs across Canada.

RESULTS

Sixty-four residents completed the LNA. About 52% reported discomfort introducing the pubertal examination, 50% reported a lack of confidence related to the examination, and 56% reported having avoided a warranted examination. Ninety-seven residents participated in the LM assessment. The baseline results were similar to those from the LNA in terms of discomfort, lack of confidence, and avoidance related to pubertal examinations. However, the intervention group showed improvement on a knowledge assessment compared with control group (p < .001). Confidence levels also improved in the intervention group LM (p < .01). Most residents (95%) stated they found the LM to be useful.

CONCLUSIONS

Residents report being uncomfortable with and avoiding the pubertal examination and have significant knowledge gaps. The online, case-based LM used in this study improved the knowledge and confidence related to this aspect of pediatric care and may be an effective adjunct to pediatric training.

Non-invasive optical spectroscopic monitoring of breast development during puberty

Background

Tanner staging (TS), a five-stage classification indicating no breast tissue (TS1) to full breast development (TS5), is used both in health research and clinical care to assess the onset of breast development (TS2) and duration in each stage. Currently, TS is measured both visually and through palpation but non-invasive methods will improve comparisons across settings.

Methods

We used optical spectroscopy (OS) measures from 102 girls at the Ontario site of the LEGACY girls study (average age 12 years, range 10.0–15.4 years) to determine whether breast tissue optical properties map to each TS. We further examined whether these properties differed by age, body mass index (BMI), and breast cancer risk score (BCRS) by examining the major principal components (PC).

Results

Age and BMI increased linearly with increasing TS. Eight PCs explained 99.9% of the variation in OS data. Unlike the linear increase with age and BMI, OS components had distinct patterns by TS: the onset of breast development (TS1 to TS2) was marked by elevation of PC3 scores indicating an increase in adipose tissue and decrease in signal from the pectoral muscle; transition to TS3 was marked by elevation of PC6 and PC7 and decline of PC2 scores indicating an increase in glandular or dense tissue; and transition to TS4+ by decline of PC2 scores representing a further increase in glandular tissue relative to adipose tissue. Of the eight PCs, three component scores (PC4, PC5, and PC8) remained in the best-fitting model of BCRS, suggesting different levels of collagen in the breast tissue by BCRS.

Conclusions

Our results suggest that serial measures of OS, a non-invasive assessment of breast tissue characteristics, can be used as an objective outcome that does not rely on visual inspection or palpation, for studying drivers of breast development.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-017-0805-x) contains supplementary material, which is available to authorized users.

Development of the human breast

Mammalia are so named based on the presence of the mammary gland in the breast. The mammary gland is an epidermal appendage, derived from the apocrine glands. The human breast consists of the parenchyma and stroma, originating from ectodermal and mesodermal elements, respectively. Development of the human breast is distinctive for several reasons. The human breast houses the mammary gland that produces and delivers milk through development of an extensive tree-like network of branched ducts. It is also characterized by cellular plasticity, with extensive remodeling in adulthood, a factor that increases its susceptibility to carcinogenesis. Also, breast development occurs in distinct stages via complex epithelial-mesenchymal interactions, orchestrated by signaling pathways under the regulation of systemic hormones. Congenital and acquired disorders of the breast often have a basis in development, making its study essential to understanding breast pathology.