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Leo Dunkel

Abstract. The responses of serum prolactin (Prl) to metoclopramide and LH and FSH to GnRH were studied simultaneously in 9 boys with hypogonadotrophic hypogonadism (HH), 7 boys with constitutional delay of puberty (D) and 15 controls. Metoclopramide increased the Prl levels in all groups. The boys with HH had lower Prl responses than the controls, whereas the boys with D had similar responses to the controls. Of the 9 boys with HH, 8 had subnormal Prl responses, 3 subnormal LH and none subnormal FSH. A metoclopramide test is clearly more sensitive than a GnRH test in differentiating HH and D and appears to make the differentiation between these two conditions clearer.

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Leo Dunkel

The Food and Drug Administration (FDA) approved the use of biosynthetic GH for the treatment of children with idiopathic short stature (ISS) in the US in 2003. Primarily, the decision was based on two studies: a randomized placebo-controlled study and a dose–response study, both demonstrating an increase in adult height over the predicted height at baseline and over placebo-treated controls by an average of 4–7 cm. Despite these data and FDA approval of GH treatment for ISS, there is still a significant controversy among paediatric endocrinologists about how, and to what extent, GH should be used in this indication. GH is clearly efficacious in several growth disorders and has the potential to alleviate debilitating short stature. However, it has been questioned whether ISS should be considered a condition warranting pharmacological treatment, whether the degree of morbidity of untreated ISS is clinically significant, and whether improved psychosocial status or well-being is achieved through GH treatment and height gain. The benefits must outweigh treatment costs and risks to justify GH treatment in ISS. The safety of GH treatment in ISS has been the main subject in two recent articles from pharmaceutical companies that conducted the pioneering studies mentioned earlier. No new safety concerns were observed in the ISS populations, but there were some limitations in study designs that prevent clinicians, their patients and families from ‘resting assured’. Studies addressing these controversial issues are needed before the widespread use of GH treatment in ISS is warranted.

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Leo Dunkel and Richard Quinton

Puberty is the period during which we attain adult secondary sexual characteristics and reproductive capability. Its onset depends upon reactivation of pulsative GNRH, secretion from its relative quiescence during childhood, on the background of intact potential for pituitary–gonadal function. This review is intended: to highlight those current practices in diagnosis and management that are evidence based and those that are not; to help clinicians deal with areas of uncertainty with reference to physiologic first principles; by sign-posting relevant data arising from other patient groups with shared issues; to illustrate how recent scientific advances are (or should be) altering clinician perceptions of pubertal delay; and finally, to emphasise that the management of men and women presenting in advanced adult life with absent puberty cannot simply be extrapolated from paediatric practice. There is a broad spectrum of pubertal timing that varies among different populations, separated in time and space. Delayed puberty usually represents an extreme of the normal, a developmental pattern referred to as constitutional delay of growth and puberty (CDGP), but organic defects of the hypothalamo–pituitary–gonadal axis predisposing to hypogonadism may not always be initially distinguishable from it. CDGP and organic, or congenital hypogonadotrophic hypogonadism are both significantly more common in boys than girls. Moreover, around 1/3 of adults with organic hypogonadotrophic hypogonadism had evidence of partial puberty at presentation and, confusingly, some 5–10% of these subsequently may exhibit recovery of endogenous gonadotrophin secretion, including men with Kallmann syndrome. However, the distinction is crucial as expectative (‘watch-and-wait’) management is inappropriate in the context of hypogonadism. The probability of pubertal delay being caused by organic hypogonadism rises exponentially both with increasing age at presentation and the presence of associated ‘red flag’ clinical features. These ‘red flags’ comprise findings indicating lack of prior ‘mini-puberty’ (such as cryptorchidism or micropenis), or the presence of non-reproductive congenital defects known to be associated with specific hypogonadal syndromes, e.g. anosmia, deafness, mirror movements, renal agenesis, dental/digital anomalies, clefting or coloboma would be compatible with Kallmann (or perhaps CHARGE) syndrome. In children, interventions (whether in the form or treatment or simple reassurance) have been historically directed at maximising height potential and minimising psychosocial morbidity, though issues of future fertility and bone density potential are now increasingly ‘in the mix’. Apubertal adults almost invariably harbour organic hypogonadism, requiring sensitive acknowledgement of underlying personal issues and the timely introduction of sex hormone replacement therapy at more physiological doses.

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Leo Dunkel and Ilpo Huhtaniemi

Abstract.

To investigate the role of gonadotropins in postnatal testicular activation, testosterone responsiveness to human chorionic gonadotropin was studied in 11 male infants (aged 5-180 days). The boys were given a single im injection of 5000 IU/1.7m2 hCG, and serum and salivary testosterone responses were then measured for 7 days. The results were compared with the serum testosterone responses of 8 older prepubertal boys (aged 1.7-10.4 years) studied with the same protocol. The mean (±sem) basal serum testosterone levels were 2.67±1.27 nmol/l in the infants and 0.09±0.02 nmol/l in the prepubertal boys (p<0.05). Both groups gave a significant response to hCG stimulation (p<0.001, ANOVA, one-way). The stimulated concentrations of serum testosterone were higher in the infants than in the prepubertal boys (p<0.001). The mean basal level of salivary testosterone was 30.5 ±7.0 and the mean maximal level was 97± 10.3 pmol/l in the infants (p<0.001). No age-related changes were observed in either basal or hCG-stimulated levels. In infants the mean (±sem) maximal hCG-stimulated increase was 25 ± 10-fold in serum and 8±4-fold in saliva (p=0.13). A clear stimulatory effect of hCG on testicular testosterone production was found, suggesting that the postnatal increase in serum testosterone concentration in male infants is gonadotropin-mediated. Salivary testosterone concentrations can be increased by hCG, indicating that measurements of salivary testosterone may provide an optional, non-invasive method for assessing gonadal function in children.

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Taneli Raivio, Anne M Wikström, and Leo Dunkel

Background: Boys with prepubertal onset of hypogonadotropic hypogonadism (HH) are at a risk of poor testis growth and impaired spermatogenesis. One potential cause for this is deficient proliferation of immature Sertoli cells before and during puberty due to the absence of FSH.

Objective: To evaluate the effects of recombinant human FSH (r-hFSH) and human chorionicgonadotropin (hCG) on testicular function and pubertal development in boys with prepubertal onset of HH.

Design: Retrospective clinical study.

Setting: Two university central hospitals, pediatric referral endocrinology outpatient clinics.

Patients: Fourteen boys (aged, 9.9–17.7 years) with prepubertal (testicular volume (TV) <3 ml) onset of HH (idiopathic HH, n=2; Kallman syndrome, n=2; idiopathic panhypopituitarism, n=4; organic panhypopituitarism, n=6).

Intervention: Treatment with r-hFSH alone (2 mo–2.8 years) prior to induction of puberty with the combination of FSH and hCG.

Main outcome measures: Progression of puberty, change in serum inhibin B, spermatogenesis.

Results: r-hFSH alone increased testicular volume twofold, from 0.9±0.6 ml (mean±s.d.) to 1.8 ± 1.1 ml (P<0.005), and serum inhibin B threefold, from 27±14 to 80±57 pg/ml (P<0.01). Three boys with an apparent absence of postnatal hypothalamic–pituitary–testicular axis activation displayed attenuated inhibin B responses to long-term (≥1 year) r-hFSH (P<0.01). Further significant increase in both TVand inhibin B occurred with induction of puberty with FSH and hCG (P<0.001). Seven boys provided semen samples: one had azoospermia, and others displayed a maximal sperm count range from 2.9 to 92 million/ml (median 8.5 million/ml).

Conclusions: (i) r-hFSH induces prepubertal testis growth and increases circulating inhibin B levels, findings suggesting proliferation of immature Sertoli cells. (ii) Puberty was successfully induced with hCG and r-hFSH following r-hFSH priming. (iii) Inhibin B appears useful for monitoring spermatogenetic activity in boys treated with hCG. (iv) Despite the extremely small initial testis volume, six out of seven patients (86%) primed with r-hFSH displayed sperm in the ejaculate suggesting beneficial effect of r-hFSH priming on testicular function later in life.

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Leo Dunkel, Liisa Hovi, and Martti A. Siimes

Abstract. Cranial irradiation is known to affect the neuroendocrine control of GH secretion. The aim of the present study was to clarify the effect of leukaemia treatment on neuroendocrine control of PRL secretion in long-term survivors of acute lymphoblastic leukaemia (ALL). Pituitary LH, FSH and PRL responses to GnRH and to the dopamine receptor antagonist metoclopramide were evaluated in 18 boys 1.6–9 years after discontinuation of medication for ALL. All the boys had been subjected to prophylactic cranial irradiation and 8 to testicular irradiation. Eight of the boys had supranormal gonadotropin levels either basally or after GnRH. All had normal basal PRL levels, but in 14 of the 18 boys the metoclopramide-releasable PRL levels were subnormal. The decreased PRL responses cannot be explained by the hypergonadotropism, since exaggerated rather than decreased responses are frequently found in patients with primary gonadal failure. We conclude that abnormal regulation of PRL secretion is a frequent consequence of treatment of ALL, probably being due to decreased pituitary lactotrop mass.

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Matti Hero, Carina Ankarberg-Lindgren, Marja-Riitta Taskinen, and Leo Dunkel

Objective: In males, the pubertal increase in sex hormone production has been associated with proatherogenic changes in lipid and carbohydrate metabolism. Aromatase inhibitors, a novel treatment modality for some growth disorders, may significantly influence these risk factors for cardiovascular disease by suppressing oestrogen biosynthesis and stimulating gonadal androgen production. In the current study, we explored the effects of aromatase inhibition on lipid metabolism, insulin sensitivity, body composition and serum adiponectin in peripubertal boys.

Design: Prospective, double-blind, randomised, placebo-controlled clinical study.

Methods: Thirty-one boys, aged 9.0–14.5 years, with idiopathic short stature were treated with the aromatase inhibitor letrozole (2.5 mg/day) or placebo for 2 years. During the treatment, the concentrations of sex hormones, IGF-I, lipids, lipoproteins and adiponectin were followed-up. The percentage of fat mass (FM) was assessed by skinfold measurements and insulin resistance by homeostasis model assessment (HOMA) index.

Results: In pubertal boys, who received letrozole, high-density lipoprotein cholesterol (HDL-C) decreased by 0.47 mmol/l (P<0.01) during the study. Simultaneously, their percentage of FM decreased from 17.0 to 10.5 (P<0.001), in an inverse relationship with serum testosterone. The concentrations of low-density lipoprotein cholesterol, triglycerides and HOMA index remained at pretreatment level in both groups. Serum adiponectin decreased similarly in letrozole- and placebo-treated pubertal boys (2.9 and 3.3 mg/l respectively).

Conclusions: In males, aromatase inhibition reduces HDL-C and decreases relative FM after the start of puberty. The treatment does not adversely affect insulin sensitivity in lean subjects.

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Helen L Storr, Leo Dunkel, Julia Kowalczyk, Martin O Savage, and Louise A Metherell

Objective and design

GH insensitivity (GHI) encompasses growth failure, low serum IGF1 and normal/elevated serum GH. By contrast, IGF1 insensitivity results in pre- and postnatal growth failure associated with relatively high IGF1 levels. From 2008 to 2013, 72 patients from 68 families (45M), mean age 7.1 years (0.4–17.0) with short stature (mean height SDS −3.9; range −9.4 to −1.5), were referred for sequencing.

Methods

As a genetics referral centre, we have sequenced appropriate candidate genes (GHR, including its pseudoexon (6Ψ), STAT5B, IGFALS, IGF1, IGF1R, OBSL1, CUL7 and CCDC8) in subjects referred with suspected GHI (n=69) or IGF1 insensitivity (n=3).

Results

Mean serum IGF1 SDS was −2.7 (range −0.9 to −8.2) in GHI patients and 2.0, 3.7 and 4.4 in patients with suspected IGF1 insensitivity. Out of 69 GHI patients, 16 (23%) (19% families) had mutations in GH–IGF1 axis genes: homozygous GHR (n=13; 6 6Ψ, two novel IVS5ds+1 G to A) and homozygous IGFALS (n=3; one novel c.1291delT). In the GHI groups, two homozygous OBSL1 mutations were also identified (height SDS −4.9 and −5.7) and two patients had hypomethylation in imprinting control region 1 in 11p15 or mUPD7 consistent with Silver–Russell syndrome (SRS) (height SDS −3.7 and −4.3). A novel heterozygous IGF1R (c.112G>A) mutation was identified in one out of three (33%) IGF1-insensitive subjects.

Conclusion

Genotyping contributed to the diagnosis of children with suspected GHI and IGF1 insensitivity, particularly in the GHI subjects with low serum IGF1 SDS (<−2.0) and height SDS (<−2.5). Diagnoses with similar phenotypes included SRS and 3-M syndrome. In 71% patients, no diagnosis was defined justifying further genetic investigation.

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Tero Varimo, Leo Dunkel, Kirsi Vaaralahti, Päivi J Miettinen, Matti Hero, and Taneli Raivio

Objective

Makorin ring finger protein 3 (MKRN3) gene restrains the hypothalamic–pituitary–gonadal axis. In girls, peripheral levels of MKRN3 decline prior to the onset of puberty. We described longitudinal changes in serum MKRN3 levels in boys before and during puberty and assessed the effect of inhibition of estrogen biosynthesis on MKRN3 levels.

Design

Longitudinal serum samples from a double-blind, randomized controlled study in 30 boys (age range: 9.1–14.2years) with idiopathic short stature who received placebo (Pl; n=14) or aromatase inhibitor letrozole (Lz; 2.5mg/day; n=16) for 2years.

Methods

We analyzed the relationships between serum MKRN3 and clinical and biochemical markers of puberty by using summary measures.

Results

Serum MKRN3 declined by 669±713 pg/mL per year (P<0.001). This change was biphasic, as the levels decreased during Tanner genital stage G1 (–2931±2750 pg/mL per year) and plateaued thereafter (–560±1510 pg/mL per year) (P<0.05). During G1, MKRN3 levels in Lz-treated subjects decreased slower than in Pl-treated boys (–782±3190 vs –2030±821 pg/mL per year, P<0.05). The decrease in serum MKRN3 levels in G1 was associated with increases in LH (r=–0.5, P<0.01), testosterone (r=–0.6, P<0.01), and inhibin B (r=–0.44, P<0.05) (n=26).

Conclusion

Peripheral MKRN3 levels in boys appear to serve as a readout of the diminishing central inhibition that controls the onset of puberty.

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Emily Cottrell, Claudia P Cabrera, Miho Ishida, Sumana Chatterjee, James Greening, Neil Wright, Artur Bossowski, Leo Dunkel, Asma Deeb, Iman Al Basiri, Stephen J Rose, Avril Mason, Susan Bint, Joo Wook Ahn, Vivian Hwa, Louise A Metherell, Gudrun E Moore, and Helen L Storr

Objective

Copy number variation (CNV) has been associated with idiopathic short stature, small for gestational age and Silver-Russell syndrome (SRS). It has not been extensively investigated in growth hormone insensitivity (GHI; short stature, IGF-1 deficiency and normal/high GH) or previously in IGF-1 insensitivity (short stature, high/normal GH and IGF-1).

Design and methods

Array comparative genomic hybridisation was performed with ~60 000 probe oligonucleotide array in GHI (n = 53) and IGF-1 insensitivity (n = 10) subjects. Published literature, mouse models, DECIPHER CNV tracks, growth associated GWAS loci and pathway enrichment analyses were used to identify key biological pathways/novel candidate growth genes within the CNV regions.

Results

Both cohorts were enriched for class 3–5 CNVs (7/53 (13%) GHI and 3/10 (30%) IGF-1 insensitivity patients). Interestingly, 6/10 (60%) CNV subjects had diagnostic/associated clinical features of SRS. 5/10 subjects (50%) had CNVs previously reported in suspected SRS: 1q21 (n = 2), 12q14 (n = 1) deletions and Xp22 (n = 1), Xq26 (n = 1) duplications. A novel 15q11 deletion, previously associated with growth failure but not SRS/GHI was identified. Bioinformatic analysis identified 45 novel candidate growth genes, 15 being associated with growth in GWAS. The WNT canonical pathway was enriched in the GHI cohort and CLOCK was identified as an upstream regulator in the IGF-1 insensitivity cohorts.

Conclusions

Our cohort was enriched for low frequency CNVs. Our study emphasises the importance of CNV testing in GHI and IGF-1 insensitivity patients, particularly GHI subjects with SRS features. Functional experimental evidence is now required to validate the novel candidate growth genes, interactions and biological pathways identified.