IDSD2026 Poster Abstracts Poster Abstracts (93 abstracts)
I-HH: longitudinal insights into diagnosis, treatment and fertility outcomes in hypogonadotropic hypogonadism
Rachel Varughese 1 , Elisabeth Laurer 2 , Sebastian Castro 3 , Yoon Hi Cho 4 , Mehul Dattani 5,6 , Ruben Willemsen 7 , Jillian Bryce 8 , Malika Alimussina 8 , Aleksandra Kapczuk 8 , S Faisal Ahmed 8 , Wolfgang Högler 2 , Rodolfo Rey 3 , Sabine Heger 9 , Anna Nordenstrom 10 , Julia Rohayem 11 & Sasha R Howard 1
1Centre for Endocrinology, William Harvey Research Institute, Queen Mary University of London, United Kingdom; 2Department of Pediatrics and Adolescent Medicine, Johannes Kepler University Linz, Linz, Austria; 3Centro de Investigaciones Endocrinológicas “Dr. César Bergadá” (CEDIE), CONICET – FEI – División de Endocrinología, Hospital de Niños Ricardo Gutiérrez, Buenos Aires, Argentina; 4The Children’s Hospital at Westmead, Sydney Children’s Hospitals Network, Australia; 5Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom; 6UCL Institute of Child Health, London, United Kingdom; 7Royal London Hospital, Barts Health NHS Trust, London, United Kingdom; 8University of Glasgow, Scotland, United Kingdom; 9Children’s Hospital Hannover, Germany; 10Karolinska Institutet, Astrid Lindgren Children’s Hospital, Sweden; 11.Children’s Hospital of Eastern Switzerland, St. Gallen, Switzerland. Correspondence to Rachel Varughese: [email protected]
Background: Hypogonadotropic hypogonadism (HH) is a heterogeneous disorder of pubertal development with long-term fertility implications. The I-HH registry (SDM Registry Module 4) collects longitudinal international clinical, imaging and genetic data to define phenotype-genotype relationships and evaluate treatment strategies, including sex steroid and gonadotropin therapies. Mini-puberty (neonatal hypothalamic-pituitary-gonadal axis activation) is increasingly recognised as an important early marker for later testicular function. Early hormonal replacement during infancy remains highly experimental and is undertaken in very few specialist centres, necessitating global data collection.
Methods: Registry data to October 2025 were analysed; updated analyses to April 2026 will be presented at the conference. The core registry includes 107 unique patients (66 male; 41 female); 63 patients have detailed longitudinal assessments. We summarised olfactory subtype, genital anomalies, genetics, imaging, hormone therapy and fertility outcomes. The registry has been amended to collect mini-puberty data to assess its role as a severity marker and the impact of early hormonal replacement on later pubertal and fertility outcomes.
Results: Of 107 patients, 51 had anosmic HH and 55 normosmic HH. In the longitudinal cohort (n = 63), micropenis was recorded in 10 males; undescended testes in 16 (12 bilateral); orchidopexy in 18. Pathogenic/likely pathogenic variants were identified in 23 patients (predominantly ANOS1, FGFR1, PROP1, NR0B1, CHD7). MRI abnormalities were common. Testosterone was used in 29 males and gonadotropins in 20 (13 received both). Limited semen data showed marked heterogeneity, both in gonadotropin regimens and spermatogenic response.
Conclusions: The I-HH registry is a powerful platform for longitudinal study of HH. Current data highlight the burden of early genital anomalies and provide substantial genetic diagnostic yield. Diverse therapeutic pathways and variable clinical responses highlight the need for robust evidence to guide hormonal management. Importantly, the registry’s forthcoming mini-puberty dataset will inform whether absence of neonatal HPG activation predicts poorer spermatogenic outcomes and whether early, targeted gonadotropin therapy can mitigate that risk. This international registry offers the first realistic opportunity to determine whether early mini-puberty replacement therapy can alter the natural history of HH and enable severity-stratified, personalised fertility management.
Volume 118
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Endocrine Abstracts
ISSN 1470-3947 (print) | ISSN 1479-6848 (online)
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