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Objective: The hypothalamic-pituitary-testicular axis is characterised by the existence of major functional changes from its establishment in fetal life until the end of puberty. The assessment of serum testosterone and gonadotrophins and semen analysis, typically used in the adult male, is not applicable during most of infancy and childhood. On the other hand, the disorders of gonadal axis have different clinical consequences depending on the developmental stage at which the dysfunction is established. This review addresses the approaches to evaluate the hypothalamic-pituitary-testicular axis in the newborn, during childhood and at pubertal age., Design: We focused on the hormonal laboratory and genetic studies as well as on the clinical signs and imaging studies that guide the aetiological diagnosis and the functional status of the gonads., Results: Serum gonadotrophin and testosterone determination is useful in the first 3-6 months after birth and at pubertal age, whereas AMH and inhibin B are useful biomarkers of testis function from birth until the end of puberty. Clinical and imaging signs are helpful to appraise testicular hormone actions during fetal and postnatal life., Conclusions: The interpretation of results derived from the assessment of hypothalamic-pituitary-testicular in paediatric patients requires a comprehensive knowledge of the developmental physiology of the axis to understand its pathophysiology and reach an accurate diagnosis of its disorders., (© 2023 John Wiley & Sons Ltd.)

Objective: Compensatory hypertrophy has been classically described in patients with monorchidism. However, it remains unclear whether there is a functional compensatory activity of the different cell populations. Our aim was to assess the functional capacity of the solitary testis in monorchid males from infancy through puberty in order to determine whether the remaining gonad is capable of compensating the functional activity of Sertoli and Leydig cells of the absent gonad., Design: In a retrospective, cross-sectional, analytical study performed at a tertiary paediatric public hospital, we included 89 boys with monorchidism and 358 healthy controls, aged 6 months-18 years. Testicular volume and circulating levels of reproductive hormones were compared between patients with monorchidism and normal boys. Serum anti-Müllerian hormone (AMH) and FSH were used as biomarkers of the functional mass of prepubertal Sertoli cells, whereas serum testosterone and LH were used as biomarkers of Leydig cells., Results: In the vast majority of the cases, the testicular volume of monorchid boys was smaller than the sum of the volume of both testes of healthy controls. Serum AMH was lower and FSH was higher in patients with monorchidism than in controls aged <3 and >13 years. Serum testosterone and LH did not differ significantly between patients and controls., Conclusion: In boys and adolescents with monorchidism, there is a dissociated capacity of the remaining testis to compensate for the absence of the other gonad: while Leydig cell function is largely compensated, Sertoli cell proliferation and function was lower than in controls., (© 2016 European Society of Endocrinology.)

Introduction: Hematopoietic malignancies are the most frequent type of cancer in childhood. Recent advances in cancer treatment have significantly improved survival until adulthood. There is an extensive literature on the effects of cancer treatment on the gonadal axis in adult survivors of childhood cancer mainly focused on sperm production, but scarce information exists on the immediate impact of cancer and its treatment in boys. Objectives: In this work, we determined the status of the hypothalamicpituitary- testicular (HPT) axis function at diagnosis and the immediate impact of chemotherapy at the start of treatment in children and adolescents with hematopoietic malignancies. Subjects and methods: In a prospective study of 94 boys and adolescents with acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML) or non- Hodgkin lymphoma (NHL), we determined serum AMH, inhibin B and FSH to assess the gonadotrophin-Sertoli cell component of the HPT axis, and testosterone and LH to evaluate the gonadotrophin-Leydig cell component, at diagnosis and after 3 months of chemotherapy. Secondarily, the general health state was evaluated. Results: In prepubertal boys, at diagnosis, AMH, inhibin B and FSH were lower compared to the reference population, reflecting an FSH-Sertoli cell axis dysfunction. After 3 months of chemotherapy, all hormone concentrations increased. At pubertal age, at diagnosis, AMH and inhibin B were lower compared to the reference population for Tanner stage, with inappropriately normal FSH, suggesting a primary Sertoli cell dysfunction with insufficient gonadotrophin compensation. The LH-Leydig cell axis was mildly disrupted. After 3 months of chemotherapy, inhibin B and AMH were unchanged while median FSH levels rose to values that exceeded the reference range, indicating a significant impairment of Sertoli cell function. Testosterone normalized concomitantly with an abnormal LH elevation reflecting a compensated Leydig cell impairment. General health biomarkers were impaired at diagnosis and improved after 3 months. Conclusion: The HPT axis function is impaired in boys with hematopoietic malignancies before the initiation of chemotherapy. There is a primary testicular dysfunction and a concomitant functional central hypogonadism that could be due to an impaired overall health. The HPT axis function improves during the initial 3 months of chemotherapy concomitantly with the general health state. However, in pubertal boys the dysfunction persists as shown by elevated gonadotropin levels after 3 months. [ABSTRACT FROM AUTHOR]

Disorders of Sex Development (DSD) are congenital anomalies in which there is a discordance between chromosomal, genetic, gonadal, and/or internal/external genital sex. In XY individuals, the process of fetal sex differentiation can be disrupted at the stage of gonadal differentiation, resulting in gonadal dysgenesis, a form of early fetal-onset primary hypogonadism characterized by insufficient androgen and anti-Müllerian hormone (AMH) production, which leads to the development of ambiguous or female genitalia. The process of sex differentiation can also be disrupted at the stage of genital differentiation, due to isolated defects in androgen or AMH secretion, but not both. These are forms of fetal-onset hypogonadism with dissociated gonadal dysfunction. In this review, we present a perspective on impaired testicular endocrine function, i.e., fetal-onset male hypogonadism, resulting in incomplete virilization at birth. [ABSTRACT FROM AUTHOR]

Study Question: Does standardised treatments used in children and adolescents with haematologic malignancies, including acute lymphoblastic (ALL) or myeloid leukaemia (AML) and non-Hodgkin lymphoma (NHL), affect endocrine function of the developing testes?Summary Answer: Therapy of haematologic malignancies do not provoke an overt damage of Sertoli and Leydig cell populations, as revealed by normal levels of anti-Müllerian hormone (AMH) and testosterone, but a mild primary testicular dysfunction may be observed, compensated by moderate gonadotropin elevation, during pubertal development.What Is Known Already: Evidence exists on the deleterious effect that chemotherapy and radiotherapy have on germ cells, and some attention has been given to the effects on Leydig and Sertoli cells of the adult gonads, but information is virtually non-existent on the effects of oncologic treatment on testicular somatic cell components during childhood and adolescence.Study Design, Size, Duration: A retrospective, analytical, observational study included 97 boys with haematological malignancies followed at two tertiary paediatric public hospitals in Buenos Aires, Argentina, between 2002 and 2015.Participants/materials, Setting, Methods: Clinical records of males aged 1-18 years, referred with the diagnoses of ALL, AML or NHL for the assessment of gonadal function, were eligible. We assessed serum levels of AMH and FSH as biomarkers of Sertoli cell endocrine function and testosterone and LH as biomarkers of Leydig cell function.Main Results and the Role Of Chance: All hormone levels were normal in the large majority of patients until early pubertal development. From Tanner stage G3 onwards, while serum AMH and testosterone kept within the normal ranges, gonadotropins reached mildly to moderately elevated values in up to 35.9% of the cases, indicating a compensated Sertoli and/or Leydig cell dysfunction, which generally did not require hormone replacement therapy.Limitations, Reasons For Caution: Serum inhibin B determination and semen analysis were not available for most patients; therefore, we could not conclude on potential fertility impairment or identify whether primary Sertoli cell dysfunction resulted in secondary depleted spermatogenesis or whether primary germ cell damage impacted Sertoli cell function.Wider Implications Of the Findings: The regimens used in the treatment of boys and adolescents with ALL, AML or NHL in the past two decades seem relatively safe for endocrine testicular function; nonetheless, a mild primary testicular endocrine dysfunction may be observed, usually compensated by slightly elevated gonadotropin secretion by the pituitary in adolescents, and not requiring hormone replacement therapy. No clinically relevant risk factor, such as severity of the disease or treatment protocol, could be identified in association with the compensated endocrine dysfunction.Study Funding/competing Interest(s): This work was partially funded by grants PIP 11220130100687 of Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and PICT 2016-0993 of Fondo para la Investigación Científica y Tecnológica (FONCYT), Argentina. R.A.R., R.P.G. and P.B. have received honoraria from CONICET (Argentina) for technology services using the AMH ELISA. L.A.A. is part-time employee of CSL Behring Argentina. The other authors have no conflicts of interest to disclose. [ABSTRACT FROM AUTHOR]

The classical definition of hypogonadism, used in adult medicine, as gonadal failure resulting in deficient steroid and gamete production, and its classification into hypergonadotropic and hypogonadotropic refer to primary gonadal and hypothalamic–pituitary disorders respectively and may lead to under- or misdiagnosis in pediatrics. Indeed, in children with primary gonadal failure, gonadotropin levels may be within the reference range for age. Conversely, since gonadotropins and steroids are normally low during childhood, it may prove impossible to show the existence of a hypogonadotropic state before pubertal age. Anti-Müllerian hormone (AMH) and inhibin B arise as more adequate biomarkers to assess gonadal function and increase the possibility of making an earlier diagnosis of hypogonadism in children, which may positively impact on timely management. Like many other definitions of clinical conditions, that of hypogonadism has been coined for adults. The disregard of a broader definition applicable to all developmental stages may result in underdiagnosis, especially in pediatric patients. Fetal hypogonadism in males results in ambiguous or female genitalia if established in the first trimester, and in small male genitalia and cryptorchidism if established in the second or third trimester, whereas in females it is clinically unremarkable. While gonadotropins and sex steroids are informative for the diagnosis of hypogonadism in infancy, pubertal age, and adulthood, Sertoli and granulosa cell biomarkers – AMH and inhibin B – are the only useful biomarkers during childhood. In childhood, primary hypogonadism is not always hypergonadotropic and the diagnosis can be missed in up to ∼70% of the cases if based on serum gonadotropin measurement. With the currently available clinical and biochemical assessments, the diagnosis of central (hypogonadotropic) hypogonadism is virtually impossible to prove during childhood. Chronic hormone replacement of hypogonadism is usually not necessary during childhood, but could prove beneficial during infancy. [ABSTRACT FROM AUTHOR]

Introduction: The functional capacity of the testes in prepubertal boys with cryptorchidism before treatment has received very little attention. The assessment of testicular function at diagnosis could be helpful in the understanding of the pathophysiology of cryptorchidism and in the evaluation of the effect of treatment. Anti-Müllerian hormone is a well-accepted Sertoli cell biomarker to evaluate testicular function during childhood without the need for stimulation tests. Objective: The aim of the study was to assess testicular function in prepubertal children with cryptorchidism before orchiopexy, by determining serum anti-Müllerian hormone (AMH). We also evaluated serum gonadotropins and testosterone and looked for associations between testicular function and the clinical characteristics of cryptorchidism. Materials and methods: We performed a retrospective, cross-sectional, analytical study at a tertiary pediatric public hospital. All clinical charts of patients admitted at the outpatient clinic, and recorded in our database with the diagnosis of cryptorchidism, were eligible. The main outcome measure of the study was the serum concentration of AMH. Secondary outcome measures were serum LH, FSH, and testosterone. For comparison, serum hormone levels from a normal population of 179 apparently normal prepubertal boys were used. Results: Out of 1,557 patients eligible in our database, 186 with bilateral and 124 with unilateral cryptorchidism were selected using a randomization software. Median AMH standard deviation score was below 0 in both the bilaterally and the unilaterally cryptorchid groups, indicating that testicular function was overall decreased in patients with cryptorchidism. Serum AMH was significantly lower in boys with bilateral cryptorchidism as compared with controls and unilaterally cryptorchid patients between 6 months and 1.9 years and between 2 and 8.9 years of age. Serum AMH below the normal range reflected testicular dysfunction in 9.5-36.5% of patients according to the age group in bilaterally cryptorchid boys and 6.3-16.7% in unilaterally cryptorchid boys. FSH was elevated in 8.1% and LH in 9.1% of boys with bilateral cryptorchidism, most of whom were anorchid. In patients with present testes, gonadotropins were only mildly elevated in less than 5% of the cases. Basal testosterone was mildly decreased in patients younger than 6 months old, and uninformative during childhood. Conclusion: Prepubertal boys with cryptorchidism, especially those with bilaterally undescended gonads, have decreased AMH production. Although serum AMH may fall within the normal range, there is a considerable prevalence of testicular dysfunction during childhood in this frequent condition. [ABSTRACT FROM AUTHOR]

Commonly known for testosterone secretion, the testes also produce the protein hormones anti-müllerian hormone (AMH), inhibin B, and insulin-like factor 3 (INSL3). AMH and inhibin B are secreted by Sertoli cells, whereas INSL3 is a Leydig cell product. AMH is involved in fetal sex differentiation and induces the regression of the anlagen of the uterus and fallopian tubes. INSL3 participates in fetal testicular descent. Serum testicular protein hormone assessment can be very useful and complementary to testosterone measurements in patients with DSD. AMH and inhibin B determination is extremely helpful during childhood, when basal testosterone is normally low. Serum AMH and inhibin B above the female range are indicative of the presence of testicular tissue, and their circulating levels reflect the amount of functional Sertoli cells. In DSD patients with normal male levels of AMH and inhibin B, the diagnosis of gonadal dysgenesis can be ruled out, and isolated androgen secretion deficiency or androgen insensitivity should be suspected. In externally virilized XY patients with persistent müllerian ducts, serum AMH levels determine the diagnosis to AMH deficiency or resistance. At pubertal age, inhibin B levels serve to predict spermatogenic development. [ABSTRACT FROM AUTHOR]

In early fetal development, the testis secretes - independent of pituitary gonadotropins - androgens and anti-Müllerian hormone (AMH) that are essential for male sex differentiation. In the second half of fetal life, the hypothalamic-pituitary axis gains control of testicular hormone secretion. Follicle-stimulating hormone (FSH) controls Sertoli cell proliferation, responsible for testis volume increase and AMH and inhibin B secretion, whereas luteinizing hormone (LH) regulates Leydig cell androgen and INSL3 secretion, involved in the growth and trophism of male external genitalia and in testis descent.This differential regulation of testicular function between early and late fetal periods underlies the distinct clinical presentations of fetal-onset hypogonadism in the newborn male: primary hypogonadism results in ambiguous or female genitalia when early fetal-onset, whereas it becomes clinically undistinguishable from central hypogonadism when established later in fetal life. The assessment of the hypothalamic-pituitary-gonadal axis in male has classically relied on the measurement of gonadotropin and testosterone levels in serum. These hormone levels normally decline 3-6 months after birth, thus constraining the clinical evaluation window for diagnosing male hypogonadism. The advent of new markers of gonadal function has spread this clinical window beyond the first 6 months of life. In this review, we discuss the advantages and limitations of old and new markers used for the functional assessment of the hypothalamic-pituitary-testicular axis in boys suspected of fetal-onset hypogonadism. [ABSTRACT FROM AUTHOR]

Male hypogonadism implies decreased function of one or more testicular cell population, i.e. germ, Leydig and/or Sertoli cells. In the normal prepubertal boy, Sertoli cells are very active, as indicated by high anti-Müllerian hormone (AMH) and inhibin B secretion, whereas the functional activity of Leydig cells is minimal, as evidenced by low testosterone production, and germ cells do not undergo the full spermatogenic process. Klinefelter syndrome is the most frequent cause of hypogonadism in the adult male. In this review, we discuss whether the gonadal failure is already established during infancy and childhood. In Klinefelter syndrome, there is increased germ cells degeneration from mid-foetal life - resulting in a decreased number at birth - which persists during infancy and childhood and becomes dramatic during puberty. Controversial results exist in the literature regarding Leydig cell function in Klinefelter boys: while some authors have found normal to low testosterone levels in infancy and childhood, others have reported normal to high values. Sertoli cell products AMH and inhibin B are normal in prepubertal boys and only decline during mid- to late puberty. Klinefelter syndrome is a primary hypogonadism affecting all testicular cell populations. Germ cells are affected from foetal life, and a severe depletion occurs at puberty. Leydig cell function may be normal or mildly affected in foetal and early postnatal life. Sertoli cell function is not impaired until mid- to late puberty, as reflected by normal AMH and inhibin B in Klinefelter boys. [ABSTRACT FROM AUTHOR]

In the prepubertal male, Sertoli cells are the most active testicular cell population. Without stimulation tests, prepubertal hypogonadism can only be evidenced if Sertoli cell function is assessed. Anti-müllerian hormone (AMH) is a distinctive marker of the prepubertal Sertoli cell. Serum AMH is high from fetal life until puberty. In postnatal life, AMH testicular production is stimulated by FSH and potently inhibited by androgens. In anorchid patients, AMH is undetectable. In prepubertal males with fetal- or childhood-onset primary or central hypogonadism affecting the whole gonad, serum AMH is low. Conversely, when hypogonadism only affects Leydig cells (i.e., LH/human chorionic gonadotrophin receptor or steroidogenic enzyme defects), serum AMH is normal/high. AMH is also normal/high in patients with androgen insensitivity. In patients of pubertal age with central hypogonadism, AMH is low for Tanner stage - reflecting lack of FSH stimulus, - but high for age - reflecting lack of testosterone inhibitory effect. FSH treatment results in serum AMH rise, whereas human chorionic gonadotrophin treatment increases testosterone levels which inhibit AMH production. In conclusion, AMH determination is helpful in assessing gonadal function, without need for stimulation tests, and orientates the aetiological diagnosis of paediatric male hypogonadism. Furthermore, serum AMH is an excellent marker of FSH and androgen action in the testis. Copyright © 2010 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]