Mikkel G. Mieritz

Validity of Self-Assessment of Pubertal Maturation

BACKGROUND AND OBJECTIVES: Studies of adolescents often use self-assessment of pubertal maturation, the reliability of which has shown conflicting results. We aimed to examine the reliability of child and parent assessments of healthy boys and girls. METHODS: A total of 898 children (418 girls, 480 boys, age 7.4–14.9 years) and 1173 parents (550 daughters, 623 sons, age 5.6–14.7 years) assessed onset of puberty or development of breasts, genitals, and pubic hair according to Tanner stages by use of a questionnaire and drawings. Physicians’ assessments were blinded and set as the gold standard. Percentage agreement, κ, and Kendall’s correlation were used to analyze the agreement rates. RESULTS: Breast stage was assessed correctly by 44.9% of the girls (κ = 0.28, r = 0.74, P < .001) and genital stage by 54.7% of the boys (κ = 0.33, r = 0.61, P < .001). For pubic hair stage 66.8% of girls (κ = 0.55, r = 0.80, P < .001) and 66.1% of boys (κ = 0.46, r = 0.70, P < .001) made correct assessments. Of the parents, 86.2% correctly assessed onset of puberty in girls (κ = 0.70, r = 0.71, P < .001) and 68.4% in boys (κ = 0.30, r = 0.37, P < .001). Children who underestimated were younger and children who overestimated older than their peers who made correct assessments. Girls and their parents tended to underestimate, whereas boys overestimated their pubertal stage. CONCLUSIONS: Pubertal assessment by the child or the parents is not a reliable measure of exact pubertal staging and should be augmented by a physical examination. However, for large epidemiologic studies self-assessment can be sufficiently accurate for a simple distinction between prepuberty and puberty.

The 2014 Danish references from birth to 20 years for height, weight and body mass index

To construct new Danish growth charts for 0‐ to 20‐year‐olds and to compare them with Danish references from 1982 and with World Health Organization (WHO) standards for children aged 0–5 years from 2006, by applying similar inclusion and exclusion criteria.

The physiology and timing of male puberty.

Purpose of reviewTo describe available markers of male puberty, discuss associations between adiposity and pubertal timing and to review recent evidence of a possible secular trend in male pubertal timing. Recent findingsAn expert panel reviewing existing American pubertal data from boys in 2005 could not confirm a secular trend in male pubertal timing. National Health and Nutrition Examination Survey III findings have been confirmed by the National Institute of Child Health and Human Development study reporting a mean age of 10.4 years for Caucasian boys entering Tanner stage G2. Furthermore, the Copenhagen Puberty Study reported a 3 months decline in pubertal onset during a 15-year period (from 11.92 years in 1991 to 11.66 years in 2008).A negative association between obesity and early puberty was found in the National Institute of Child Health and Human Development study, in contrast to the positive association found in a Danish study. Other studies have not been able to document an association between prepubertal BMI and age at pubertal onset. SummaryEvaluation of Tanner stage and especially assessment of testicular volume should both be used in epidemiological studies. We speculate that the association between fat mass and pubertal timing may be nonlinear and recent studies may indicate a small decline in age at pubertal onset in boys.

Body fat throughout childhood in 2647 healthy Danish children: agreement of BMI, waist circumference, skinfolds with dual X-ray absorptiometry.

Background/Objectives:Total body fat percentage (%BF) evaluated by dual energy X-ray absorptiometry (DXA) scans (DXA %BF) is widely recognized as a precise measure of fatness. We aimed to establish national reference curves for DXA %BF, %BF calculated from skinfolds (SF %BF) and waist circumference (WC) in healthy children, and to compare agreement between the different methods.Subjects/Methods:Based on 11 481 physical examinations (anthropometry) and 1200 DXA scans from a longitudinal cohort of Danish children (n=2647), we established reference curves (LMS-method) for SF %BF, WC (birth to 14 years) and DXA %BF (8–14 years). Age- and sex-specific Z-scores for body mass index (BMI), WC and SF %BF were compared. Sensitivity and specificity were calculated for agreement of WC, SF %BF and BMI with DXA %BF to identify obese children (>+1 s.d.).Results:%BF differed with age, sex, pubertal stage and social class. SF %BF correlated strongly with DXA %BF (r=0.86). BMI and WC also correlated positively with DXA %BF (Z-scores; r= 0.78 and 0.69). Sensitivity and specificity were 79.5 and 93.8 for SF %BF, 75.9 and 90.3 for BMI and 59.2 and 95.4 for WC.Conclusions:SF %BF showed the highest correlation and best agreement with DXA %BF in identifying children with excess fat (+1 s.d.).

Urinary phthalate excretion in 555 healthy Danish boys with and without pubertal gynaecomastia

Pubertal gynaecomastia is a clinical sign of an oestrogen-androgen imbalance, which occurs in 40-60% of adolescent Caucasian boys. In most cases no underlying endocrinopathy can be identified. A recent study reports higher plasma phthalate levels in Turkish boys with pubertal gynaecomastia. Therefore, we asked whether there was an association between concurrent measures of urinary phthalate metabolites and pubertal timing as well as the presence of gynaecomastia in otherwise healthy boys. We studied a total of 555 healthy boys (age 6.07-19.83 years) as part of the COPENHAGEN Puberty Study. Anthropometry and pubertal stages (PH1-6 and G1-5) were evaluated, and the presence of gynaecomastia was assessed. Non-fasting blood samples were analysed for serum testosterone and morning urine samples were analysed for the total content of 12 phthalate metabolites (MEP, MnBP, MiBP, MBzP, MEHP, MEHHP, MEOHP, MECPP, MiNP, MHiNP, MiONP and MCiOP) by LC-MS/MS. A statistically significant negative correlation was observed between chronological age and the urinary concentration of the sum of measured metabolites DEHP (∑DEHPm) (r = -0.164) and DiNP (∑DiNPm) (r = -0.224), respectively, and the sum of monobutyl phthalate (MBP) isomers (∑MBP((i+n))) (r = -0.139) (all with p < 0.01). In contrast urinary monoethyl phthalate concentration was positively correlated to age (r = 0.187, p < 0.01). The urinary levels of phthalate metabolites were not associated with age at pubertal onset, serum testosterone levels or presence of gynaecomastia. In conclusion, we did not find evidence of anti-androgenic effects of phthalates in our healthy boys. Thus, current phthalate exposure was not associated with pubertal timing, testosterone levels or with the presence of pubertal gynaecomastia in this cross-sectional study. However, longitudinal studies are needed to evaluate possible perinatal or long-term postnatal effects of phthalates on healthy boys.

Circulating MKRN3 Levels Decline Prior to Pubertal Onset and Through Puberty: A Longitudinal Study of Healthy Girls

CONTEXT Puberty is initiated by a complex interaction of suppressing and stimulating factors. Genetic studies of familial central precocious puberty have suggested makorin ring finger protein 3 (MKRN3) as a major inhibitor of GnRH secretion during childhood. Furthermore, genetic variation near MKRN3 (rs12148769) affects age at menarche in healthy girls. OBJECTIVE The purpose of this study was to evaluate whether serum levels of MKRN3 declined before pubertal onset in healthy girls. DESIGN This was a population-based longitudinal study of healthy Danish girls and a cohort study of early maturing girls. SETTING The study was performed in the general community and in a tertiary referral center for pediatric endocrinology. PATIENTS OR OTHER PARTICIPANTS Healthy girls (n = 38) aged 9.3 years (range, 5.9-11.3 years) at baseline and followed for 6.0 years (2.7-7.6 years) (2006-2014) with blood sampling every 6 months and early maturing girls (n = 13) with breast development ay <8.3 years of age were included. MAIN OUTCOME MEASURES Serum levels of MKRN3 were measured in 354 samples (median, 9 per girl; range, 2-14 per girl), and genotyping of variants near MKRN3 (rs12148769 and rs12439354) was performed. RESULTS MKRN3 concentrations declined preceding pubertal onset; the geometric mean (95% confidence interval) 3 years before pubertal onset vs the last visit before pubertal onset was 304 pg/mL (264-350 pg/mL) vs 257 pg/mL (243-273 pg/mL), corresponding to a reduction of 15% (1-27%) (P = .033). In prepubertal girls, circulating MKRN3 correlated negatively with gonadotropin levels: for FSH, r = -0.262 (P = .015) and for LH, r = -0.226 (P = .037). After adjustment, MKRN3 levels were lower in early maturing girls than in age-matched prepubertal girls: 171 pg/mL (<25-333 pg/mL) vs 262 pg/mL (94-624 pg/mL) (P = .051). Genetic variants near MKRN3 did not correlate with serum levels of MKRN3. CONCLUSIONS Declining levels of circulating MKRN3 preceded pubertal onset. The negative correlation between MKRN3 and gonadotropins further supports MKRN3 as a major regulator of hypothalamic GnRH secretion during childhood. Undetectable or low MKRN3 levels were observed in a subgroup of patients with early onset of puberty.

Circulating AMH Reflects Ovarian Morphology by Magnetic Resonance Imaging and 3D Ultrasound in 121 Healthy Girls

CONTEXT In adult women, Anti-Müllerian hormone (AMH) is produced by small growing follicles, and circulating levels of AMH reflect the number of antral follicles as well as primordial follicles. Whether AMH reflects follicle numbers in healthy girls remains to be elucidated. OBJECTIVE This study aimed to evaluate whether serum levels of AMH reflects ovarian morphology in healthy girls. DESIGN AND SETTING This was a population-based cohort study involving the general community. PARTICIPANTS Included in the study were 121 healthy girls 9.8-14.7 years of age. MAIN OUTCOME MEASURES Clinical examination, including pubertal breast stage (Tanners classification B1-5), ovarian volume, as well as the number and size of antral follicles were assessed by two independent modalities: magnetic resonance imaging (MRI), Ellipsoid volume, follicles ≥2 mm; and Transabdominal ultrasound, Ellipsoid and 3D volume, follicles ≥1 mm. Circulating levels of AMH, inhibin B, estradiol, FSH, and LH were assessed by immunoassays; T and androstenedione were assessed by liquid chromatography-tandem mass spectrometry. RESULTS AMH reflected the number of small (MRI 2-3 mm) and medium (4-6 mm) follicles (Pearsons Rho [r] = 0.531 and r = 0.512, P < .001) but not large follicles (≥7 mm) (r = 0.109, P = .323). In multiple regression analysis, small and medium follicles (MRI ≤ 6 mm) remained the main contributors to circulating AMH (β, 0.501; P < .001) whereas the correlation between AMH and estradiol was negative (β, -0.318; P = .005). In early puberty (B1-B3), the number of AMH-producing follicles (2-6 mm) correlated positively with pubertal stages (r = 0.453, P = .001), whereas AMH levels were unaffected (-0.183, P = .118). CONCLUSIONS Similarly to adult women, small and medium antral follicles (≤6 mm) were the main contributors to circulating levels of AMH in girls.

Evaluation of 451 Danish Boys With Delayed Puberty: Diagnostic Use of a New Puberty Nomogram and Effects of Oral Testosterone Therapy

CONTEXT Few data exist on the diagnostic criteria, and on the effects of puberty induction, in boys with constitutional delay in growth and puberty (CDGP). OBJECTIVE To develop puberty nomograms based on Danish boys with normal pubertal development. To evaluate the different diagnostic criteria and the effect of oral testosterone undecanoate (TU) in boys with CDGP. DESIGN A cross-sectional and longitudinal study of Danish boys with normal pubertal development (COPENHAGEN puberty study). A retrospective observational study of 451 boys evaluated for delayed puberty between 1990 and 2013. SETTING Tertiary referral center for pediatric endocrinology. PARTICIPANTS One hundred and sixty-four (36%) boys evaluated for CDGP were excluded due to missing data, reclassification, or associated comorbidities, yielding 287 (64%) eligible for analysis. MAIN OUTCOME MEASURES The number of patients with CDGP classified by the puberty nomogram (genital stage < -2 SD for age) versus the classical criteria (genital stage 1 at ≥ 14 years). The effect of one year of oral TU treatment on pubertal progression, circulating hormones, height, and predicted adult height (PAH). RESULTS Seventy-eight (27%) of the 287 boys had delayed pubertal onset according to the classical criteria, whereas 173 (60%) of the 287 boys had impaired pubertal progression according to the puberty nomogram. Ninety-six (56%) of these 173 boys were treated with oral TU for 0.8 years (0.5; 1.3) [median (25th; 75th percentiles)], which resulted in beneficial effects on pubertal progression. Height increased from -1.9 SD (-2.5; -1.2) to -1.5 SD (-2.1; -0.7) (P < .001), and PAH increased from 172.3 cm (170.3; 182.8) to 178.1 cm (171.4; 191.7) (P = .001) following one year of treatment. CONCLUSIONS The puberty nomogram evaluates both delayed pubertal onset as well as delayed pubertal progression and allows separation of normal versus abnormal pubertal development. Oral TU treatment was followed by pubertal induction and progression and short-term growth without compromising final height.

Pubertal Onset in Girls is Strongly Influenced by Genetic Variation Affecting FSH Action

Age at pubertal onset varies substantially in healthy girls. Although genetic factors are responsible for more than half of the phenotypic variation, only a small part has been attributed to specific genetic polymorphisms identified so far. Follicle-stimulating hormone (FSH) stimulates ovarian follicle maturation and estradiol synthesis which is responsible for breast development. We assessed the effect of three polymorphisms influencing FSH action on age at breast deveopment in a population-based cohort of 964 healthy girls. Girls homozygous for FSHR -29AA (reduced FSH receptor expression) entered puberty 7.4 (2.5–12.4) months later than carriers of the common variants FSHR -29GG+GA, p = 0.003. To our knowledge, this is the strongest genetic effect on age at pubertal onset in girls published to date.

FSHB-211 and FSHR 2039 are associated with serum levels of follicle-stimulating hormone and antimüllerian hormone in healthy girls: a longitudinal cohort study

OBJECTIVE To investigate whether genetic polymorphisms in the FSH pathway (FSHB-211 G→T and FSHR 2039 A→G) affect serum levels of FSH, antimüllerian hormone (AMH), and age at pubertal onset. FSH secretion and FSH signal transduction are enhanced in carriers of FSHB GG and FSHR AA, respectively. Furthermore, the combined genotype FSHB GG+FSHR AA is the most favorable for male gonadal function, but the effect of this genotype has never been evaluated in peripubertal females. AMH is a marker of ovarian function and is negatively correlated with FSH in prepubertal girls. DESIGN Secondary analyses of a prospective cohort study. SETTING General community. PATIENT(S) We examined 78 healthy girls twice yearly for 6 years; the median age at baseline was 9.3 years. INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) Hormone levels were measured by immunoassays, and DNA was isolated from blood and genotyped by restriction fragment length polymorphism of polymerase chain reaction-amplified regions. RESULT(S) Carriers of FSHB GG+FSHR AA had higher FSH before pubertal onset (median 2.2 vs. 1.5 IU/L) and lower AMH (13.8 vs. 19.4 pmol/L) compared with carriers of other genotypes. In crude analysis, girls with FSHB GG+FSHR AA entered puberty earlier, 9.7 vs. 10.6 years. However, the difference was no longer statistically significant after including interval-, right-, and left-censored data in a probit analysis. CONCLUSION(S) The combined effect of FSHB GG+FSHR AA may potentiate the FSH pathway, which increases serum levels of FSH and reduces AMH. Common variations in genes regulating follicle growth may affect AMH levels independently of the number of resting primordial follicles.