Testosterone is the major androgen in circulation in male humans, produced primarily in the Leydig cells of the testis. Biosynthesis of testosterone from cholesterol occurs via a series of enzymatic reactions. Testosterone may be further metabolized into a more potent androgen, dihydrotestosterone. In recent years an alternate pathway of dihydrotestosterone biosynthesis without using testosterone as a precursor has emerged. Majority of classically studied effects of androgens are thought to be mediated via nuclear receptor-dependent long-term transcriptional effects, but there also exist membrane receptor-based effects of androgens which are being uncovered from recent studies that may explain rapid effects of androgens in many cases. In this chapter we are describing the biosynthesis, mechanism of action, and therapeutic effects of testosterone and related androgens.

CONTEXT:Levels of glucocorticoid (GC) precursors are elevated in preterm infants, whereas clinical signs of GC deficiency are frequently observed in neonatal intensive care units. OBJECTIVE:To describe the maturation of the GC metabolic pathway in preterm infants during the first year of life. DESIGN AND SETTING:Spot urinary samples (n = 154) were collected in the neonatal intensive care unit and at follow-up visits. PARTICIPANTS:Sixteen preterm infants (8 boys) born <30 weeks of gestational age. Data of full-term infants were available from the same laboratory. MAIN OUTCOME MEASURES:Urinary levels of GC precursor metabolites and 13 GC metabolites were quantitated by gas chromatography-mass spectrometry. Enzyme activities were calculated by product/substrate ratios. Mixed models were used for statistical analyses. RESULTS:The levels of GC precursors remained high in preterm infants until term-equivalent age (TEA), after which they decreased (P < .001). However, GC production, estimated by the sum of 13 GC metabolites did not change significantly over time in preterm infants and was higher in preterm than in full-term infants after 1 week of age (P = .044 -<.001). The sum of 13 GC metabolites/tetrahydro-11-deoxycortisol ratio (representing CYP11B1 activity) increased in preterm infants after TEA (P < .001), whereas the 16α-OH-DHEA/5-PT ratio (representing 17,20-lyase activity) decreased (P < .001). The ratio of cortisone metabolites to cortisol metabolites was higher in preterm infants before TEA than thereafter (P < .001). CONCLUSION:Despite a high production rate of GC precursors in preterm infants, the total GC production remained relatively constant and was regulated at the level of CYP11B1. Persisting differences between preterm and full-term infants in GC precursor levels as well as in GC production were observed, indicating possible programming effects of preterm birth.

OBJECTIVE:Treatment monitoring of individuals with congenital adrenal hyperplasia (CAH) remains unsatisfactory. Comprehensive 24 h urine steroid profiling provides detailed insight into adrenal steroid pathways. We investigated whether 24 h urine steroid profiling can predict treatment control in children and adolescents with CAH using machine learning (ML). DESIGN:Prospective observational cohort study. METHODS:This study included children with 21-hydroxylase deficiency. On 24 h urines of 2 consecutive visits 40 steroids were measured by gas chromatography-mass spectrometry. Treatment outcome was clinically classified as undertreated, optimally treated or overtreated. We used sparse partial least squares discriminant analysis (sPLS-DA) to investigate prediction of treatment outcome. We computed area under the ROC-curve (AUC) of 2 sPLS-DA models: (1) using only 24 h urine metabolites and (2) adding clinical variables. RESULTS:We included 112 visits (68 optimal, 44 undertreatment) from 59 patients: 27 (46%) girls, 46 (78%) classic CAH, and 19 (32%) prepubertal. Mean age at first visit was 11.9 ± 4.0 years and mean BMI SDS 0.6 ± 1.1. SPLS-DA using 24 h urine metabolites showed clear clustering of optimally treated patients on 2 components, while undertreated patients were more heterogeneous (AUC 0.88). The model selected pregnanetriol and 17α-hydroxypregnanolone contributing to excluding optimal treatment and 5 metabolites contributing to excluding undertreatment: 17β-estradiol, cortisone, tetrahydroaldosterone, androstenetriol, and etiocholanolone. Addition of clinical variables marginally improved classification (AUC 0.90). CONCLUSIONS:Using ML on 24 h urine steroid profiling predicted treatment outcome in children with CAH, even in the absence of clinical data, suggesting that routine comprehensive 24 h urine steroid profiling could improve treatment monitoring in CAH.

Differences of sex development (DSD) represent a group of congenital conditions that affect human sex development and maturation owing to discrepancies of chromosomal, gonadal and phenotypic sex. The Chicago consensus classifies DSD as sex chromosome DSD, 46,XY DSD and 46,XX DSD, with subclassifications according to gonadal determination into testes and ovaries and hormone-dependent differentiation of Müllerian and Wolffian embryonic structures into female-typical or male-typical internal and external sex organs. DSD may occur as an isolated condition or as part of a complex syndrome. Diagnosis is based on clinical characteristics, imaging studies, hormonal measurements and genetic investigations. Management includes lifelong psychosocial support, hormonal treatments and surgical interventions that require personalization for each case as DSD encompasses a wide variety of aetiologies and presentations. This personalization must also consider individual values and preferences to ensure that clinical care is tailored to meet the unique needs and circumstances of each person, ideally provided by a care team with diverse specialities. This care involves psycho-educational counselling on the condition and its consequences, considering family and cultural norms. Additional efforts are needed to bridge gaps in knowledge related to diagnosis, management and long-term outcomes. Enhancing our understanding of the distinctions between sex and gender in societies is essential as greater awareness will inform and enrich public debates. Differences of sex development (DSD) encompass a group of rare congenital conditions characterized by atypical sex development. In this Primer, Flück and colleagues provide insights into our current understanding of rare DSD pathophysiology, its prevalence and diagnosis as well as challenges and controversies related to clinical management.

Immortalized adrenal, placental and gonadal cell models are often termed steroidogenic based on steroid hormone production and steroidogenic enzymes. Profiling of 'classic' steroid metabolites is common; however, downstream untargeted metabolites remain unidentified. This study characterized steroidogenesis in human adrenal H295R and H295A; placental BeWo and JEG-3; mouse Leydig MA-10; and mouse adrenal Y-1 and OS-3 cells. Steroids were determined under basal, stimulated and serum-free conditions using liquid chromatography-mass spectrometry. This study identified distinct differences in mineralocorticoid and glucocorticoid production in the two human adrenal models and between the human and mouse adrenal models; unconventional hydroxylated progesterone steroid metabolites in all models which were most abundant in MA-10 cells; glucocorticoids and abundant classical androgens in MA-10 cells; 11-oxy androgens in H295R, H295A and MA-10 cells; comparable levels of the classical androgens in H295R and MA-10 cells, while 11-oxy androgen were more abundant in H295R and H295A cells; and high pregnenolone and progesterone in placental models with limited hydroxylated progesterone metabolites. Our detailed protocols and comprehensive steroid profiles provide an invaluable guide to researchers for in vitro investigations into steroidogenesis.

3β-Hydroxysteroid dehydrogenase 2 deficiency (3βHSD2D) is a rare form of congenital adrenal hyperplasia (CAH) with variable clinical presentation. We describe a 46, XY child with ambiguous genitalia and CAH without apparent adrenal insufficiency due to 2 novel heterozygous variants in the HSD3B2 gene (c.779C > T/p.Pro260Leu and c.307 + 1G > A/p.Gly103Asp,fs29X). The disease-causing effect of the novel variants was assessed by genetic and functional studies informing on positive genotype-phenotype correlation. Sex registration was female, and no gender dysphoria has been noted until the present age of 7 years, but psychological assessments have been difficult with a concomitant diagnosis of autism spectrum disorder. Virilization that already progresses prepubertally through peripheral conversion of androgen precursors by 3β-hydroxysteroid dehydrogenase 1 will pose an increasing challenge during puberty.

BACKGROUND:Endocrine science remains underrepresented in European Union research programs despite the fundamental role of hormone health in human wellbeing. Analysis of the CORDIS database reveals a persistent gap between the societal impact of endocrine disorders and their research prioritization. At national funding level, endocrine societies report limited or little attention of national research funding towards endocrinology. The EndoCompass project-a joint initiative between the European Society of Endocrinology and the European Society of Paediatric Endocrinology, aimed to identify and promote strategic research priorities in endocrine science to address critical hormone-related health challenges. METHODS:Research priorities were established through comprehensive analysis of the EU CORDIS database covering the Horizon 2020 framework period (2014-2020). Expert consultation was conducted to identify key research priorities, followed by broader stakeholder engagement including society members and patient advocacy groups. RESULTS:Research priorities encompass variations in sex development, hypothalamic-pituitary-gonadal regulation, and female and male reproductive disorders. Key areas include improving diagnostic capacity through (epi)genetic analysis, optimizing hormonal treatments, developing fertility preservation strategies. Special emphasis is placed on establishing pan-European registries, developing novel reproductive technologies, and exploring environmental impacts on reproductive health. CONCLUSIONS:This component of the EndoCompass project provides an evidence-based roadmap for strategic research investment. This framework identifies crucial investigation areas into reproductive and developmental endocrinology pathophysiology, prevention, and treatment strategies, ultimately aimed at reducing the burden of these disorders on individuals and society. The findings support the broader EndoCompass objective of aligning research funding with areas of the highest potential impact in endocrine health.

Objective:Reliable data on prevalence of differences of sex development (DSD) are lacking. We aimed to estimate population-based prevalence of DSD among pediatric endocrine care centers in Switzerland. Design:Retrospective population-based study including children and adolescents with DSD according to Chicago Consensus, born in Switzerland from 2000 through 2019. Methods:Endocrine departments in 10 Swiss Children's Hospitals and 8 private endocrine practices collected DSD data through the I-DSD registry or case report forms. We calculated prevalence for DSD diagnostic groups and analyzed trends in prevalence. Results:Over the 20-year study period, we identified 561 individuals with DSD. Almost half (n = 266, 47%) had sex chromosome DSD, 177 (32%) had 46,XY DSD, and 118 (21%) had 46,XX DSD. Causes for 46,XY DSD were disturbed androgen synthesis or action (37/177, 21%), atypical gonadal development (28/177, 16%), or other causes (112/177, 63%). Causes for 46,XX DSD were androgen excess (99/118, 84%), atypical gonadal development (8/118, 7%), or other causes (11/118, 9%). On average, 28 new cases were born with DSD annually. Prevalence was 17 for sex chromosome DSD, 12 for 46,XY DSD, and 8 for 46,XX DSD per 100 000 live births and year. One per 7500 newborn girls had 46,XX congenital adrenal hyperplasia. Conclusion:Prevalence of sex chromosome DSD was underreported due to late diagnosis. Prevalence of 46,XX congenital adrenal hyperplasia is similar to newborn screening data, suggesting good completeness of cases. For complex DSD cases, we expect complete coverage. This study provides a valuable resource for policymaking and (inter)national research on DSD.

Introduction: Non-classic lipoid congenital adrenal hyperplasia (LCAH) presents with adrenal insufficiency but typically lacks a gonadal phenotype or features a delayed-onset gonadal presentation. Information on fertility outcomes in affected individuals is limited. Case Presentation: We describe an adult male with severe, early-onset primary adrenal insufficiency, yet normal fertility, diagnosed in mid-adulthood with compound heterozygous STAR gene variants, including both known and novel mutations. The identified variants, c.814C>T (p.Arg272Cys) and c.743A>C (p.Lys248Thr), underwent structural and functional analysis, revealing partial enzymatic activity. A review of existing reports on the gonadal phenotype and fertility in non-classic LCAH identified only nine adult males. Among these, five exhibited normal gonadal function, but none had documented paternity. Conclusion: STAR variants may be present in adults with unresolved primary adrenal insufficiency and normal gonadal function. Infertility is not an inevitable outcome, as demonstrated by this case.

INTRODUCTION:Adrenarche is a prepubertal developmental phase in humans characterized by increasing levels of adrenal androgens in circulation. While its regulation and biological significance remain poorly understood, the earlier onset of adrenarche - referred to as premature adrenarche (PA) - raises concerns about potential long-term health risks, including metabolic syndrome and polycystic ovary syndrome. Our study aimed to elucidate the regulatory mechanisms underlying adrenarche and PA, specifically investigating whether PA represents a benign variation of normal development, or a disorder associated with increased risks of unfavorable metabolic and reproductive outcomes in adulthood. METHODS:This study employs a longitudinal design to track a well-characterized cohort of children with PA alongside age-matched healthy controls, following them from adrenarche through puberty into early adulthood. Conducted across two independent research centers in Kuopio, Finland, and Bern, Switzerland, the study involves detailed phenotypic assessments, including comprehensive medical histories and body composition analyses. Biological samples undergo multi-omics profiling - encompassing transcriptomics and metabolomics - using advanced techniques such as liquid and gas chromatography tandem-mass spectrometry and RNA sequencing. This integrated approach aims to identify biomarkers predictive of adverse health outcomes in PA, with candidate biomarkers and regulatory factors further validated through in vitro adrenal cell model studies. CONCLUSION:This study provides the first comprehensive, longitudinal comparison of PA and healthy controls across critical developmental milestones. By elucidating the molecular factors that regulate the maturation of the zona reticularis, it seeks to resolve the longstanding mystery of adrenarche. Furthermore, by differentiating benign developmental variations from PA cases linked with long-term health risks, the findings could refine current diagnostic criteria and enable early identification of children at risk. Ultimately, this research paves the way for more accurate diagnoses, targeted interventions, and improved long-term health outcomes.

Most disorders of steroidogenesis, such as forms of congenital adrenal hyperplasia (CAH) are caused by mutations in genes encoding the steroidogenic enzymes and are often recognized clinically by cortisol deficiency, hyper- or hypo-androgenism, and/or altered mineralocorticoid function. Most steroidogenic enzymes are forms of cytochrome P450. Most P450s, including several steroidogenic enzymes, are microsomal, requiring electron donation by P450 oxidoreductase (POR); however, several steroidogenic enzymes are mitochondrial P450s, requiring electron donation via ferredoxin reductase (FDXR) and ferredoxin (FDX). POR deficiency is a rare but well-described form of CAH characterized by impaired activity of 21-hydroxylase (P450c21, CYP21A2) and 17-hydroxylase/17,20-lyase (P450c17, CYP17A1); more severely affected individuals also have the Antley-Bixler skeletal malformation syndrome and disordered genital development in both sexes, and hence is easily recognized. The 17,20-lyase activity of P450c17 requires both POR and cytochrome b5 (b5), which promote electron transfer. Mutations of POR, b5, or P450c17 can cause selective 17,20-lyase deficiency. In addition to providing electrons to mitochondrial P450s, FDX, and FDXR are required for the synthesis of iron-sulfur clusters, which are used by many enzymes. Recent work has identified FDXR mutations in patients with visual impairment, optic atrophy, neuropathic hearing loss, and developmental delay, resembling the global neurologic disorders seen with mitochondrial diseases. Many of these patients have had life-threatening events or deadly infections, often without an apparent triggering event. Adrenal insufficiency has been predicted in such individuals but has only been documented recently. Neurologists, neonatologists, and geneticists should seek endocrine assistance in evaluating and treating patients with mutations in FDXR.