Does height and IGF-I determine pubertal timing in girls?

BACKGROUND: Pubertal timing is closely linked to growth regulated by the growth hormone/insulin-like factor (GH/IGF) axis that includes IGF-regulating factors such as pregnancy-associated plasma protein-A/A2 (PAPP-A/PAPP-A2) and stanniocalcin 2 (STC2). We investigated the association between height, IGF-I concentration, and PAPPA, PAPPA2, and STC2 genotypes on the timing of female pubertal milestones. METHODS: Height, IGF-I, and genotypes were analyzed in 1382 Danish girls from the general population, 67 patients with tall stature (height ≥2 SD), and 124 patients with short stature (height ≤-2 SD). The main outcomes were breast stage and menarche. RESULTS: Thelarche occurred significantly earlier in patients with tall stature (mean age 9.37 years [95% confidence interval (CI) 8.87-9.87]) and later in patients with short stature (11.07 years [95% CI 10.7-11.43]) compared with girls within the normal range (9.96 years [95% CI 9.85-10.07]) (p = 0.02 and p < 0.01, respectively). Girls with higher IGF-I levels experienced thelarche and menarche earlier compared with the rest of the cohort (p < 0.01). Genotypes were not associated with age at thelarche nor menarche, but the PAPPA2 minor allele carriers were shorter compared with major allele carriers, p = 0.03. CONCLUSIONS: Height and IGF-I, but not PAPP-A, PAPP-A2, and STC2 genotypes, were negatively associated with age at thelarche and menarche. IMPACT: Girls with tall and short stature enter puberty earlier and later compared with girls with normal height. Girls with higher insulin-growth factor-I in childhood enter puberty earlier. Pubertal timing is influenced by longitudinal growth and IGF-I levels earlier in childhood. Childhood growth and the levels of IGF-I in childhood may be biomarkers of pubertal timing.

Cohort profile: The COPENHAGEN Minipuberty Study-A longitudinal prospective cohort of healthy full-term infants and their parents.

BACKGROUND: The hypothalamic-pituitary-gonadal (HPG) axis governs sexual maturation and reproductive function in humans. In early postnatal life, it is transiently active during which circulating sex steroids reach adult levels. While this so-called minipuberty represents a universal phenomenon in infants of both sexes, its role for early maturation and growth remains incompletely understood. OBJECTIVES: To provide normative data on auxology as well as serum and urinary hormone levels in healthy, full-term infants throughout the first year of life and to investigate associations of postnatal HPG axis dynamics as well as hormonal, genetic and environmental exposures with early genital development and growth. POPULATION: Healthy, Danish, full-term, singleton newborns including their parents. DESIGN: Single-centre, prospective, observational longitudinal pregnancy and birth cohort. METHODS: Newborns were followed with six repeated clinical examinations during a one-year follow-up period. An umbilical cord blood sample was drawn at birth. At each visit, infants underwent a clinical examination focusing on auxology and genital development. Further, blood (serum, plasma, DNA) and urine samples were collected at each visit. Mothers and fathers underwent a clinical examination and provided blood samples prior to and after birth. A subset of parents provided urine samples and breast milk samples. Pregnancy and obstetrical outcomes, and detailed parental questionnaires were compiled. PRELIMINARY RESULTS: Between August 2016 and August 2018, 2481 women with singleton pregnancies were invited to participate of which 298, including their partners, were enrolled (12.0%). A total of 268 healthy, full-term newborns born appropriate for gestational age (AGA) were included at birth, 233 newborns participated in the postnatal follow-up period and 186 completed the one-year follow-up period (9.4% and 7.5%, respectively). CONCLUSION: The COPENHAGEN Minipuberty Study provides detailed, longitudinal data on early genital development and growth including hormonal and genetic profiles and environmental exposure in healthy infants including additional data in their parents.

Short stature homeobox-containing gene duplications in 3.7% of girls with tall stature and normal karyotypes.

AIM: The short stature homeobox-containing gene (SHOX) plays an important role in short stature, but has not been explored in detail in a tall stature population before. This study explored the prevalence of SHOX aberrations in girls diagnosed with idiopathic tall stature with a normal karyotype. METHODS: We studied SHOX aberrations in 81 girls with a median age of 10.43 (7.17-12.73) years diagnosed with tall stature who were referred to our clinic at Copenhagen University Hospital, Denmark, between 2003 and 2013. SHOX copy variations were analysed by quantitative polymerase chain reaction, and aberrations were confirmed by multiplex ligation probe-dependent amplification. RESULTS: One extra SHOX copy was found in three (3.7%) of the 81 girls with tall stature, and their heights were 2.87, 3.71 and 3.98 standard deviation scores (SDS) and above the median height SDS of the girls with two SHOX copies. Their sitting height/height ratios (-3.08, -2.00 and -2.18 SDS) were all lower than the population mean. Despite these SHOX duplications, the three girls were clinically and biochemically comparable to the 78 girls with two SHOX copies. CONCLUSION: This study was the first to demonstrate SHOX duplications in three girls with tall stature and normal karyotypes.

Evaluation and phenotypic characteristics of 293 Danish girls with tall stature: effects of oral administration of natural 17ß-estradiol.

BACKGROUND: Reduction of adult height by sex steroid treatment was introduced decades ago in tall statured children, but controlled trials are lacking and treatment is controversial. In this study, we wanted to evaluate the phenotypic characteristics in girls referred due to tall stature and the effect of oral administration of 17ß-estradiol on predicted adult height in girls. METHODS: A single-centre retrospective observational study of 304 girls evaluated consecutively due to tall stature between 1993 and 2013. 207 patients diagnosed with constitutionally tall stature (CTS), 60 (29%) girls ended up being treated with 17ß-estradiol with a duration of 1.7 y (1.2; 2.5) (median (25; 75 percentile)), and final height was available in 26 girls. RESULTS: At baseline, 20% of girls with CTS had supranormal IGF-I, whereas reproductive hormones were within the normal range. Final adult height was reduced with 1.6 ± 2.1 cm in the girls treated with 17ß-estradiol when compared to initial prediction. Chronological age, bone age, estradiol, and IGF-I at baseline or estrogen dose did not predict height reduction. CONCLUSIONS: Serum IGF-I was elevated tall statured children, but did not predict the effect of treatment with 17ß-estradiol, which caused a modest reduction in final adult height.

Polygenic Scores for Adult Testosterone and SHBG Levels Are Associated With Reproductive Hormone Levels in Male Infants.

CONTEXT: The hypothalamic-pituitary-gonadal axis's transient activity in infancy, i.e, minipuberty, is considered crucial for male reproductive function. Historically, minipuberty has been considered a passive response triggered by the withdrawal of placental steroids at birth. However, given its potential link to adult reproductive function, we hypothesize that minipuberty is a partially genetically regulated process, suggesting a link between the genetic architecture of reproductive hormone concentrations across lifespan. OBJECTIVE: To investigate the association of UK Biobank Study-based polygenic scores (PGS) of adult total testosterone (T) and sex hormone-binding globulin (SHBG) concentrations with trajectories of reproductive hormones concentrations in male infants. DESIGN: Prospective, longitudinal birth cohort (The COPENHAGEN Minipuberty Study, 2016-2018, ClinTrial: NCT02784184). Individual PGSs in male infants derived from published literature were calculated for total T and SHBG. The associations with mean SD scores (SDS) of reproductive hormone concentrations in infancy were tested. SETTING: Population-based. PATIENTS OR OTHER PARTICIPANTS: Healthy, male, term, singleton newborns were followed with repeated clinical examinations including blood sampling during a 1-year follow-up (n = 109). MAIN OUTCOME MEASURES: Circulating reproductive hormone concentrations. RESULTS: T-PGSadult were significant associated with mean T-SDSinfancy, mean SHBG-SDSinfancy, and mean LH-SDSinfancy (P = .02, <.001 and .03, with r2 = 0.05, 0.21 and 0.04, respectively). SHBG-PGSadult was significantly associated with mean SHBG-SDSinfancy (P < .001, r2 = 0.18). T-PGSadult explained 5% and 21% of the phenotypic variation in infancy of mean T-SDSinfancy and SHBG-SDSinfancy, respectively. CONCLUSION: Our findings suggest that the genetic architecture underlying total T and SHBG in adults also associates with hormone concentrations and their trajectories during infancy.

Sex- and age-specific reference intervals of 16 steroid metabolites quantified simultaneously by LC-MS/MS in sera from 2458 healthy subjects aged 0 to 77 years.

BACKGROUND: Reference intervals covering the whole life span for all the metabolites in the steroid hormone biosynthesis quantified by sensitive and robust analytical methods are sparse or not existing. OBJECTIVE: To develop a state-of-the-art LC-MS/MS method for simultaneous quantification of multiple steroid metabolites and to establish detailed sex- and age-specific reference intervals for 16 steroid metabolites. MATERIALS AND METHOD: An isotope diluted LC-MS/MS method was developed for simultaneous quantitation of 16 steroid hormones. Serum samples from cross-sectional cohorts of healthy infants, children, adolescents, and adults aged 0.17 months to 77 years (n = 2458) were analysed. RESULTS: With this novel, specific, and sensitive LC-MS/MS method, it was possible to quantify progesterone, 17-hydroxypregnenolone, 17-hydroxyprogesterone, dehydroepiandrosterone sulfate, androstenedione, testosterone, dihydrotestosterone, 11-deoxycorticosterone, corticosterone, 11-deoxycortisol, cortisol, and cortisone in ≥90 % of the samples, while estrone sulfate, aldosterone and dehydroepiandrosterone were quantified in 77 %, 75 % and 60 % of the samples, respectively. 21-deoxycortisol was only detectable in 2.5 % of samples from healthy subjects. Sex- and age-dependent fluctuations observed in minipuberty, puberty and adulthood including the menopausal transition were modelled. This enabled us to establish valid reference intervals from birth to late adult life for both males and females. CONCLUSION: Detailed sex- and age-specific reference intervals of multiple, simultaneously quantified steroid metabolites by a novel and specific LC-MS/MS method provides a valuable tool for clinical practice and for future research.

Serum LH/FSH ratios in 87 infants with differences of sex development.

The ratio between luteinizing hormone (LH) and follicle-stimulating hormone (FSH) has previously been described as an excellent marker of sex in healthy infants. However, LH/FSH remains not fully described in patients with differences of sex development (DSD). The aim was therefore to describe LH/FSH in infants with DSD. This was a retrospective study of DSD patients, all aged 0-1.2 years. In total, 87 infants with DSD and at least one serum sample per infant were included. Longitudinal samples from single patients were included whenever possible. Serum LH/FSH ratios in these patients were plotted against recently published age-related and sex-dimorphic cutoffs. Overall, LH/FSH sometimes corresponded to assigned sex without any obvious pattern in terms of diagnoses. LH/FSH corresponded to the biological sex in all patients with Turner or Klinefelter syndrome. In patients with 46,XX or 46,XY DSD (except congenital adrenal hyperplasia (CAH)), the ratios did not correspond to the assigned sex in all cases and were interchangeably within the male and female range. In patients with CAH, the ratio corresponded to biological sex (based on sex chromosomes) in some cases but also ranged across the cutoffs. In the 15 patients with 45,X/46,XY mosaicism, the LH/FSH ratios corresponded to the assigned sex in all cases (12 were raised as males, 3 as females) and at all time points in cases with multiple sampling. While this study describes LH/FSH in infants with DSD, the exact clinical role of the ratio in the management of these patients remains to be further elucidated.

Urinary concentration of phthalates and bisphenol A during minipuberty is associated with reproductive hormone concentrations in infant boys.

BACKGROUND: The transient postnatal activation of the hypothalamic-pituitary-gonadal hormone axis is termed minipuberty and considered an important developmental period, which is highly sensitive to endocrine disruption. Here, we explore exposure-outcome associations during minipuberty between concentrations of potentially endocrine disrupting chemicals (EDCs) in urine of infant boys and their serum reproductive hormone concentrations. METHODS: In total, 36 boys participating in the COPENHAGEN Minipuberty Study had data available for both urine biomarkers of target endocrine disrupting chemicals and reproductive hormones in serum from samples collected on the same day. Serum concentrations of reproductive hormones were measured by immunoassays or by LC-MS/MS. Urinary concentrations of metabolites of 39 non-persisting chemicals, including phthalates and phenolic compounds, were measured by LC-MS/MS. Nineteen chemicals had concentrations above the limit of detection in ≥50% of children and were included in data analysis. Associations of urinary phthalate metabolite and phenol concentrations (in tertiles) with hormone outcomes (age- and sex-specific SD-scores) were analysed by linear regression. Primarily, we focused on the EU regulated phthalates; butylbenzyl phthalate (BBzP), di-iso-butyl phthalate (DiBP), di-n-butyl phthalate (DnBP), and di-(2-ethylhexyl) phthalate (DEHP) as well as bisphenol A (BPA). Urinary metabolites of DiBP, DnBP and DEHP were summed and expressed as ∑DiBPm, ∑DnBPm and ∑DEHPm. RESULTS: Compared to boys in the lowest ∑DnBPm tertile, urinary concentration of ∑DnBPm was associated with concurrent higher luteinizing hormone (LH) and anti-Müllerian hormone (AMH) SD-scores as well as lower testosterone/LH ratio in boys in the middle ∑DnBPm tertile (estimates (CI 95%) 0.79 (0.04; 1.54), 0.91 (0.13; 1.68), and -0.88 (-1.58;-0.19), respectively). Further, higher insulin-like peptide 3 (INSL3) SD-scores and lower DHEAS SD-score in boys in the highest ∑DnBPm tertile (0.91 (0.12; 1.70) and -0.85 (-1.51;-0.18), respectively) were observed. In addition, boys in the middle and highest ∑DEHPm tertile had higher LH (1.07 (0.35; 1.79) and 0.71 (-0.01; 1.43), respectively) and in the highest ∑DEHPm tertile also higher AMH (0.85 (0.10; 1.61)) concentration SD-scores, respectively. Boys in the highest BPA tertile had significantly higher AMH and lower DHEAS concentration compared to boys in the lowest BPA tertile (1.28 (0.54; 2.02) and -0.73 (-1.45; -0.01)), respectively. DISCUSSION: Our findings indicate that exposure to chemicals with known or suspected endocrine disrupting potential, especially the EU-regulated DnBP, DEHP and BPA, may modify male reproductive hormone concentrations in infant boys suggesting that minipuberty is a critical window sensitive to endocrine disruption.

Exposure to 15 phthalates and two substitutes (DEHTP and DINCH) assessed in trios of infants and their parents as well as longitudinally in infants exclusively breastfed and after the introduction of a mixed diet.

OBJECTIVE: Several phthalates have been restricted/banned due to their adverse endocrine disrupting properties. The use of other phthalates and substitutes has increased. Here we examine the current exposure to phthalates in family trios comprised of infants and their parents and in infants exclusive breastfed and following introduction to a mixed diet. METHODS: Metabolites of 15 phthalates and two substitutes, di(2-ethylhexyl)-teraphthalate (DEHTP) and diisononyl-cyclohexane-1,2-dicarboxylate (DINCH), were measured in urine samples collected from >100 infants and their parents and in paired urine samples collected from 67 infants, while they were exclusively breastfed and when they got mixed diet. RESULTS: Among infants and their parents, metabolites of nine out of 15 phthalates and both substitutes were detected in >74% of all samples. Estimated daily intake (DI) calculated as µg/kg/day, showed similar exposure levels among infants and their parents for several of the substances, and infants were more exposed to DEHTP than their mothers. Significantly higher estimated DIs were observed for some low-molecular phthalates in infants exclusively breastfed. In contrast, comparable estimated DIs were observed for many other phthalates and DEHTP regardless of feeding status. For most of the substances, the within-family variation, was lower than the between-family variation. Likewise, the within-infant variation on exclusively breast vs. mixed diet was lower than the between-infant variation. Independent of food status, some infants were concurrently exposed to almost all the measured phthalates and substitutes in higher amounts than others. CONCLUSION: Surprisingly, irrespective of diet status infants were exposed to several phthalates and substitutes some of which have been regulated for years. Exposure patterns and levels were similar in infants and their parents. Importantly, risk assessment based on new refined reference doses (RfD-AA) exceeded the safety level for anti-androgenic effects in a number of infants and parents, which is of concern.

Stability and detectability of testosterone esters in dried blood spots after intramuscular injections.

While misuse of testosterone esters is widespread in elite and recreational sports, direct detection of intact testosterone esters in doping control samples is hampered by the rapid hydrolysis by esterases present in the blood. With dried blood spot (DBS) as sample matrix, continued degradation of the esters is avoided due to inactivation of the hydrolase enzymes in dried blood. Here, we have developed the method further for detection of testosterone esters in DBS with focus on robustness and applicability in doping control. To demonstrate the method's feasibility, DBS samples from men receiving two intramuscular injections of Sustanon® 250 (n = 9) or placebo (n = 10) were collected, transported, and stored prior to analysis, to mimic a doping control scenario. The presented nanoLC-HRMS/MS method appeared reliable and suitable for direct detection of four testosterone esters (testosterone decanoate, isocaproate, phenylpropionate, and propionate) after extraction from DBS. Sustanon® was detected in all subjects for at least 5 days, with detection window up to 14 days for three of the esters. Evaluation of analyte stability showed that while storage at room temperature is tolerated well for a few days, testosterone esters are highly stable (>18 months) in DBS when stored in frozen conditions. Collectively, these findings demonstrate the applicability of DBS sampling in doping control for detection of steroid esters. The fast collection and reduced shipment costs of DBS compared with urine and standard blood samples, respectively, will allow more frequent and/or large-scale testing to increase detection and deterrence.

Benzophenones, bisphenols and other polychlorinated/phenolic substances in Danish infants and their parents - including longitudinal assessments before and after introduction to mixed diet.

BACKGROUND: Humans are widely exposed to chemicals with known or suspected endocrine disrupting effects. Among those are several benzophenones, bisphenols and other phenols commonly used in consumer products. OBJECTIVES: To provide human biomonitoring data from young families including infants and their parents as well as longitudinal data of infants exclusively breastfed versus on mixed diet. METHOD: Twenty-two benzophenones, bisphenols and other phenols, were measured in urine sample sets collected from more than 100 infants and their parents (the TRIO study) and in paired samples from 61 infants when exclusively breastfed and after introduction of mixed diet (the FOOD study). RESULTS: Twelve out of 22 substances were detectable in more than half of the urine samples from infants, mothers or fathers. Large variation in excreted levels of almost all the substances were observed. The TRIO study showed that infants had comparable or even significantly higher daily urinary excretion (DUE) of benzophenone, 4-hydroxy-benzophenone, bisphenol A, bisphenol S, triclosan and 2-phenylphenol than their parents. In the FOOD study, exclusively breastfed infants had higher or similar DUE of triclosan and benzophenones compared to when they received mixed diet. Urinary levels of triclosan and the benzophenones, BP-1 and BP-3 were significantly correlated between all trio members, indicating exposure from the same sources at home. For triclosan, BP-1 and BP-3, the within family variation was lower than between families in the TRIO study. Many substances were positively correlated both within infants and parents, indicating that some families were exposed to several of these substances concurrently. CONCLUSION: Participants in this study excreted relatively low chemical levels, however, simultaneous exposure to several chemicals with endocrine disrupting abilities is of concern due to the dose-additive effects of these substances in combination with other chemicals.

Longitudinal evaluation of breast tissue in healthy infants: Prevalence and relation to reproductive hormones and growth factors.

Introduction: Breast tissue in infancy is a rather undescribed phenomenon. We aimed to describe the prevalence and progression of palpable breast tissue in healthy boys and girls aged 0-1 years and to evaluate clinical markers, individual serum hormone concentrations as well as combined hormone profiles as determinants of the persistence of breast tissue. Methods: In total, 233 term infants (119 boys, 114 girls) were included and followed from birth until 1 year of age in The COPENHAGEN Minipuberty Study (ClinicalTrials.gov #NTC02784184). Infants were followed up to six times with a clinical examination and serum sampling. Principal component analyses (PCAs) produced combined hormone profiles. Results: A total of 98% of all infants aged 0-1 year exhibited breast tissue at some point. 50% still had breast tissue present at 0.5-0.6 years in girls and 0.3-0.4 years in boys ('persistent'). At one year, more girls than boys had breast tissue present (p=0.010). Most clinical and hormonal markers did not differ in infants with/without persistent breast tissue. However, in those with persistent breast tissue, estradiol (first visit, girls, p=0.034), androstenedione, corticosterone, cortisol (first visit, boys, all p<0.050), length (first visit, boys, p=0.030), and testicular volume (0.3-0.4 years, p=0.040) were higher, while IGF-I (0.3-0.4, boys, p=0.033) was lower. In boys, a combined, PCA-derived hormone profile (first visit) was able to predict the persistence of breast tissue (area under the curve=83%) better than any single marker. Discussion: Palpable breast tissue in infancy is common in both sexes although it persists in significantly more girls than boys at one year of age. Data supports both the early origin of breast tissue (in utero- and early postnatal) as well as a role of endogenous hormone production in later development and maintenance.

A Biphasic Pattern of Reproductive Hormones in Healthy Female Infants: The COPENHAGEN Minipuberty Study.

CONTEXT: Minipuberty, a period of a transient activation of the hypothalamic-pituitary-gonadal (HPG) axis in both sexes, enables evaluation of gonadal function in infants suspected of hypogonadism. However, female minipuberty remains poorly elucidated. OBJECTIVE: We aimed to establish continuous reference ranges for the most commonly used reproductive hormones and to evaluate the dynamics of the HPG axis in females aged 0 to 1 year. DESIGN: The COPENHAGEN Minipuberty Study (ClinicalTrials.gov ID: NCT02784184), a longitudinal, prospective cohort study. SETTING: Healthy infants from Copenhagen. PATIENTS OR OTHER PARTICIPANTS: A total of 98 healthy, term female infants followed with 6 examinations including venipuncture during the first year of life. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Serum concentrations of LH, FSH, inhibin B, anti-Müllerian hormone (AMH), estrone (E1), estradiol (E2), and SHBG were quantified using highly sensitive methods in 266 serum samples. RESULTS: Reference ranges were established for LH, FSH, inhibin B, AMH, E1, E2, and SHBG. Two peaks were observed in normalized mean curves for all hormones. The first peaks were timed around postnatal days 15 to 27 followed by a general nadir for all hormones around days 58 to 92. The second peaks occurred around days 107 to 125 for inhibin B, AMH, E1, E2, and SHBG and days 164 to 165 for LH and FSH. CONCLUSIONS: We present age-related, continuous reference ranges of the most commonly used reproductive hormones and present novel data revealing a biphasic and prolonged female minipuberty. CLINICALTRIALS.GOV ID: NCT02784184.

Dynamic changes in LH/FSH ratios in infants with normal sex development.

Objective: Little is known about the ratio between luteinizing hormone (LH) and follicle-stimulating hormone (FSH) during infancy. This study aimed to evaluate serum and urinary LH/FSH as a marker of sex with age-specific cutoffs in healthy infants. Design: A prospective, longitudinal cohort study of healthy infants aged 0-1.2 years. Methods: In total, 236 healthy infants (122 boys and 114 girls) from The COPENHAGEN Minipuberty Study (ClinicalTrials.gov ID: NCT02784184), with 567 serum and 603 urine samples, were included. Measures of diagnostic accuracy, including sensitivity and specificity, were used to assess the ability of LH/FSH to detect sex in healthy infants. Results: In both serum and urine, LH/FSH was highest in males with minimal overlap between the sexes. In contrast to isolated LH and FSH concentrations, LH/FSH ratios in both serum and urine were excellent markers of sex from 0 to 1.2 years with median sensitivities and specificities ranging from 93 to 100% with correspondingly narrow 95% CIs. Conclusions: Serum and urinary LH/FSH ratios are excellent discriminators of sex in healthy infants during the entire first year of life. The clinical role and application of the ratio remain to be elucidated.

Timing of Puberty, Pubertal Growth, and Adult Height in Short Children Born Small for Gestational Age Treated With Growth Hormone.

CONTEXT: Growth hormone (GH) is used to treat short children born small for gestational age (SGA); however, the effects of treatment on pubertal timing and adult height are rarely studied. OBJECTIVE: To evaluate adult height and peak height velocity in short GH-treated SGA children. METHODS: Prospective longitudinal multicenter study. Participants were short children born SGA treated with GH therapy (n = 102). Adult height was reported in 47 children. A reference cohort of Danish children was used. Main outcome measures were adult height, peak height velocity, age at peak height, and pubertal onset. Pubertal onset was converted to SD score (SDS) using Danish reference data. RESULTS: Gain in height SDS from start of treatment until adult height was significant in both girls (0.94 [0.75; 1.53] SDS, P = .02) and boys (1.57 [1.13; 2.15] SDS, P < .001). No difference in adult height between GH dosage groups was observed. Peak height velocity was lower than a reference cohort for girls (6.5 [5.9; 7.6] cm/year vs 7.9 [7.4; 8.5] cm/year, P < .001) and boys (9.5 [8.4; 10.7] cm/year vs 10.1 [9.7; 10.7] cm/year, P = .002), but no difference in age at peak height velocity was seen. Puberty onset was earlier in SGA boys than a reference cohort (1.06 [-0.03; 1.96] SDS vs 0 SDS, P = .002) but not in girls (0.38 [-0.19; 1.05] SDS vs 0 SDS, P = .18). CONCLUSION: GH treatment improved adult height. Peak height velocity was reduced, but age at peak height velocity did not differ compared with the reference cohort. SGA boys had an earlier pubertal onset compared with the reference cohort.

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.

Dynamic Changes of Reproductive Hormones in Male Minipuberty: Temporal Dissociation of Leydig and Sertoli Cell Activity.

CONTEXT: The male hypothalamic-pituitary-gonadal (HPG) axis is transiently active during the first months of life with surging serum concentrations of reproductive hormones. This period, termed minipuberty, appears to be essential for priming testicular function. Despite the central role for male reproductive function, longitudinal data on HPG axis activation in infancy is sparse. OBJECTIVE: To explore the dynamics of HPG hormone activity in healthy male infants, to assess the association of HPG axis activity and testicular volume, and to establish reference curves for serum levels of reproductive hormones. DESIGN: Prospective, longitudinal birth cohort (the COPENHAGEN Minipuberty Study, 2016-2018, 1-year follow-up). SETTING: Population-based. PATIENTS OR OTHER PARTICIPANTS: Healthy, male, term, singleton newborns were followed from birth on with repeated clinical examinations including blood sampling during a 1-year follow-up. A total of 128 boys contributed to this study, while 119 participated in the postnatal follow-up. MAIN OUTCOME MEASURES: Serum reproductive hormone concentrations and testicular volume. RESULTS: Reproductive hormone concentrations showed marked dynamics during the first 6 months of age. Gonadotropins, total testosterone, and insulin-like factor 3 peaked at around 1 month of age. Inhibin B, anti-Müllerian hormone, and testicular volume peaked at around 4 to 5 months. Correlations largely recapitulated typical HPG axis pathways but also differed significantly from adult men. CONCLUSIONS: We demonstrate a temporal dissociation of Leydig and Sertoli cell activity during male minipuberty and provide reference curves for reproductive hormones.

An Intramuscular Injection of Mixed Testosterone Esters Does Not Acutely Enhance Strength and Power in Recreationally Active Young Men.

Purpose: Limited data are available on the acute performance-enhancing effects of single-dose administration of testosterone in healthy humans. Studies of testosterone administrations to healthy humans are rare due to the difficult nature and necessity of close clinical monitoring. However, our unique physiological experimental facilities combined with close endocrinological collaboration have allowed us to safely complete such a study. We tested the hypothesis that an intramuscular injection of 250 mg mixed testosterone esters (TEs) enhances physical performance in strength and power exercises acutely, measured 24 h after injection. Additionally, we investigated whether the basal serum testosterone concentration influences the performance in countermovement jump (CMJ), 30-s all out cycle sprint, and one-arm isometric elbow flexion. Methods: In a randomized, double-blind, placebo-controlled design, 19 eugonadal men received either a TE (n = 9, 23 ± 1 years, 183 ± 7 cm, 83 ± 10 kg) or a PLA (n = 10, 25 ± 2 years, 186 ± 6 cm, 82 ± 14 kg) injection. Hormonal levels and the performance in CMJ, 30-s all out cycle sprint, and one-arm isometric elbow flexion were measured before and 24 h after injection. Results: Firstly, an intramuscular injection of 250 mg mixed TEs did not enhance the vertical jump height in a CMJ test, peak power, mean power, and fatigue index in a 30-s all-out cycle sprint or rate of force development and maximal voluntary contraction in a one-arm isometric elbow flexion 24 h post-injection. Secondly, baseline testosterone levels appeared not to influence performance in strength and power exercises to a large extent in healthy, recreationally active young men. Conclusion: A single intramuscular injection of 250 mg mixed TEs has no acute ergogenic effects on strength and power performance in recreationally active, young men. This novel information has implication for basic physiological understanding. Whether the same applies to an elite athlete population remains to be determined. If so, this would have implications for anti-doping efforts aiming to determine the most cost-efficient testing programs.

Changes in blood parameters after intramuscular testosterone ester injections - Implications for anti-doping.

Testosterone treatment stimulates the production of red blood cells and alters iron homeostasis. Thus, we investigated whether the 'haematological module' of the athlete biological passport (ABP) used by the World Anti-Doping Agency can be used to indicate misuse of testosterone. Nineteen eugonadal men received intramuscular injections of either 250 mg Sustanon®, a blend of four testosterone esters, or placebo on days 0 and 21 in a randomized, placebo-controlleddouble-blind design. Urine samples and blood samples were collected twice pre-treatment, at least 5 days apart, and on days 1, 3, 5, 10 and 14 post-injections to assess steroidal and haematological biomarkers of the ABP. The steroidal profile was flagged suspicious in all Sustanon®-treated subjects, whereas the haematological profile was flagged suspicious in six out of nine subjects. When both sensitivity and specificity were considered, reticulocyte percentage (RET%) appeared as the best marker of the haematological module for implying testosterone ester misuse. Atypical blood passport samples were used to select time points for further isotope-ratio mass spectrometry (IRMS) analysis of testosterone and its metabolites in simultaneously collected urine. In addition to the testosterone (T) to epitestosterone (E) ratio, the RET% and OFF-Score could help identify suspicious samples for more targeted IRMS testing. The results demonstrate that unexpected fluctuations in RET% can indicate testosterone doping if samples are collected 3-10 days after injection. From an anti-doping perspective, the haematological and steroidal modules of the ABP should complement each other when planning targeted follow-up testing and substantiating likely misuse of testosterone.

Anogenital Distance in Healthy Infants: Method-, Age- and Sex-related Reference Ranges.

CONTEXT: The use of anogenital distance (AGD) in clinical and epidemiological settings is increasing; however, sex-specific reference data on AGD and data on longitudinal changes in AGD in children is scarce. OBJECTIVE: To create age-, sex-, and method-related reference ranges of AGD in healthy boys and girls aged 0-24 months, to assess the age-related changes in AGD and to evaluate the 2 predominantly used methods of AGD measurement. DESIGN: The International AGD consortium comprising 4 centers compiled data from 1 cross-sectional and 3 longitudinal cohort studies (clinicaltrials.gov [NCT02497209]). SETTING: All data were collected from population-based studies, recruiting from 4 maternity or obstetric centers (United States, Cambridge [United Kingdom], Odense, and Copenhagen [Denmark]). SUBJECTS: This study included a total of 3705 healthy, mainly Caucasian children aged 0-24 months on whom 7295 measurements were recorded. MAIN OUTCOME MEASURES: AGDAS (ano-scrotal), AGDAF (ano-fourchette), AGDAP (ano-penile), AGDAC (ano-clitoral), AGD body size indices (weight, body mass index [BMI], body surface area, and length), and intra- and interobserver biases. RESULTS: We created age-specific reference ranges by centers. We found that AGD increased from birth to 6 months of age and thereafter reached a plateau. Changes in AGD/BMI during the first year of life were minor (0-6% and 0-11% in boys and girls, respectively). CONCLUSIONS: Reference ranges for AGD can be used in future epidemiological research and may be utilized clinically to evaluate prenatal androgen action in differences-in-sex-development patients. The increase in AGD during the first year of life was age-related, while AGD/BMI was fairly stable. The TIDES and Cambridge methods were equally reproducible.