Congenital hypogonadotrophic hypogonadism, induction of minipuberty, and future fertility

Background

Minipuberty in boys in the first few months after birth produces a surge of gonadotrophins and Sertoli cell proliferation. Patients with congenital hypogonadotrophic hypogonadism (CHH) miss out on this phase of development which is crucial for future fertility. We present a unique case documenting the long-term fertility success decades after induced minipuberty as an infant.

Case presentation

A 33-year-old man with Kallmann syndrome presented for induction of spermatogenesis.

At birth in 1983 he had bilateral cryptorchidism and micropenis. He was referred to an endocrinologist for a clinical program for cryptorchidism using pulsatile GnRH to initiate testicular testosterone production and thereby testicular descent. At the age of 12 months, he received a 2-month course of pulsatile GnRH therapy. The clinical protocol was as follows. A saline solution of GnRH (Gonadorelin, Ayerst Australia, Pty Ltd, West Ryde, NSW, Australia) was delivered as a pulse every 60–90 minutes, by a modified Graseby-Dynamics MS16 syringe driver (2 × 4.5 × 11.0 cm; weight: 115 g) worn in a vest pocket and administered via a catheter and 25 gauge scalp vein needle placed subcutaneously into the abdominal wall (1). Initial doses of GnRH were 50–100 µg per day and were increased by 50 µg every 2 weeks up to 200 µg daily as indicated by clinical or hormonal responses, either testicular descent or serum testosterone concentration. His parents changed the syringe and needle daily.

Although initial descent occurred, at 21 months of age, the right testis was not satisfactorily in the scrotum and the patient had right, but not left, orchidopexy. At the age of 5 years, he received intramuscular injections of low-dose testosterone esters (Sustanon, Apsen Pharmacare, St Leonards, NSW, Australia) for 3 months, for penile growth. At the age of 14 years, there was no pubertal development, testosterone concentration was low, and gonadotrophins were undetectable. A diagnosis of CHH was made. He resumed monthly injections of testosterone esters 50 mg increasing gradually to 250 mg monthly and subsequently 3 monthly testosterone undecanoate (Reandron 1000, Bayer Australia Ltd, Bentley, WA, Australia).

Investigation

At 33 years of age, his height was 190.5 cm and weight 101.4 kg. He had adult distribution of pubic and axillary hair with penile and scrotal development at Tanner stage 5. The right testis was 6 mL in volume (estimated by orchidometer) and in the scrotal sac. A small left testis was just palpable in the inguinal canal. He had impaired sense of smell, by self-report and formal testing, and synkinesis. Blood pressure was 120/70. Testosterone (on treatment) was 12.8 nmol/L (nomal range: 10 – 35), and gonadotrophins were undetectable. There was azoospermia. Other pituitary hormones were normal. Analysis of the ANOS1 gene identified a hemizygous mutation, NM_000216.2(ANOS1):c.[353_362del];[0], (p.Thr118Serfs*9), which results in a 10 nucleotide deletion at amino acid 118 resulting in a frame shift and premature termination at AA 126, consistent with Kallmann syndrome (classified by the American College of Medical Genetics and Genomics as ‘likely pathogenic’). The same variant was confirmed in his mother.

Treatment

The patient was treated with hCG (Pregnyl, Organon Pharma Pty Ltd, Macquarie Park, NSW, Australia) 1500 units and recombinant FSH (Gonal-F, Merck Healthcare Pty Ltd, Macquarie Park, NSW, Australia) 150 units, 3 times weekly, subcutaneously by self-injection. We advised the patient that, in light of the literature and our own clinical experience, spermatogenesis would take a long time, with an estimated delay of 15 months before the appearance of sperm in the ejaculate (2).

Outcome and follow-up

On gonadotrophin therapy, testicular size increased over 12 months to 15 mL on the right and estimated 6 mL on the left. Surprisingly, the patient’s total sperm count was 25.5 million only 12 months after starting gonadotrophin therapy. His wife conceived naturally.

Discussion

We propose that pulsatile GnRH therapy, in reality given in infancy for the purposes of testicular descent, also induced FSH-mediated proliferation of Sertoli cells, thereby facilitating the subsequent response to fertility treatment 33 years later.

The unexpectedly rapid induction of spermatogenesis contrasts with the outcomes of our other patients, and with reports in the literature, and is consistent with the now well-accepted understanding that the hormonal events in infancy, termed ‘minipuberty,’ prime the testis for future reproduction. This case further strengthens the point that CHH must be suspected in an infant with the classical signs of cryptorchidism and micropenis, that early identification of CHH is possible with hormonal assays in the window where minipuberty is expected, and that confirmation with genetic studies is achievable. Importantly, GnRH therapy, given in a physiological pulsatile manner, may rectify the absence of minipuberty and subsequently improve later response to fertility treatment.

In gestation, GnRH neurons migrate from the olfactory placode to the preoptic-hypothalamic continuum, from whence they send projections to the median eminence to secrete GnRH and stimulate gonadotrophin release by the pituitary. Failure of this process disrupts the development of the central neuroendocrine regulation of reproduction. Many genetic mutations have been identified as pathogenic to the development of this neuroendocrine network and result in CHH, including the ANOS1 mutations associated with classical Kallmann syndrome.

Males with CHH may present at birth with features of impaired androgen effect – cryptorchidism or micro-penis –, in teenage years with failure to progress into puberty or later with infertility. GnRH secretion is also responsible for minipuberty, the surge of both LH and FSH, beginning soon after birth and continuing up to 6 months of age (3). LH elicits testosterone secretion and FSH induces a four-fold increase in Sertoli cell numbers and in testicular volume, as well as increases in the secretion of inhibin B and anti-müllerian hormone (AMH) (4). Since each Sertoli cell can only support the development of a finite number of germ cells, Sertoli cell numbers are critical for subsequent sperm-producing capacity. In CHH, the lack of minipuberty, particularly its effect on Sertoli cell proliferation, is a likely factor in the universally reported prolonged course of gonadotrophin therapy needed for successful induction of spermatogenesis in adulthood. As reported by Young et al., 44 studies of the induction of spermatogenesis in men with CHH show that the mean delay until any sperm appear in the ejaculate is 15 months (2). This time frame accords with our own experience of induction of spermatogenesis in men with CHH. Factors associated with a longer time course for successful induction of spermatogenesis in men with hypogonadotrophic hypogonadism are a congenital aetiology or prepubertal onset of that condition, neonatal cryptorchidism, and being the first course of induction therapy. Factors associated with a more rapid response are postpubertal onset of hypogonadotrophic hypogonadism and being a subsequent course of induction of spermatogenesis. Therefore, our patient’s response to his initial course of induction of spermatogenesis is clearly unexpected given his diagnosis and clinical history.

The contrast between this patient’s response and that of our other patients and that reported in the literature raises the possibility that early identification of CHH in infants soon after birth, followed by early GnRH therapy given in a physiological manner, may induce minipuberty and subsequently improve their response to fertility treatment as an adult.

Despite the recognised role of androgens in testicular descent, guidelines recommend surgical orchidopexy as the first choice of treatment rather than hormonal therapy. There have been trials of hormonal therapy for cryptorchidism in the past, mainly with GnRH given intranasally three times daily, or with hCG given by intramuscular injection (5). The data from randomised controlled studies suggest that GnRH is effective in inducing testicular descent, but the size of the effect was variable and not thought sufficiently robust to be recommended as first-line therapy.

In examining the results of hormonal therapy, several conclusions may be drawn. First, not all cryptorchidism results from androgen deficiency. Second, historically, hormonal treatment of cryptorchidism has concentrated on stimulating androgen production to induce testicular descent, with less attention paid to inducing Sertoli cell proliferation. Third, hCG induces testosterone secretion but lacks FSH activity. Finally, GnRH given three times daily does not reflect the normal pulsatile secretion of GnRH. GnRH given in the physiological pulsatile manner would be more appropriate and would be expected to induce secretion of both LH and FSH.

Surely, this concept needs further exploration. The European Consensus Statement on CHH supports this view: ‘although there appears to be some promise in neonatal administration of gonadotrophins, there are only a few studies and they all have a limited number of participants, so further investigations are needed to assess the long-term outcomes of such treatment’ (6).

The efficacy of GnRH therapy for testicular descent is not the central argument in this case report. The central argument is that the finding of cryptorchidism with or without micro-penis should prompt further investigation. Although a number of aetiologies lead to cryptorchidism, CHH should not be missed since it has major implications for future pubertal development and for fertility (3). In minipuberty, although LH and FSH release occurs simultaneously, the response of testosterone, reflecting Leydig cell response to LH, occurs earlier and more briefly, peaking at 19 days, whereas the response of AMH and inhibin, both reflecting FSH-driven Sertoli cell proliferation, is later and more prolonged (7). Nevertheless, LH-driven testosterone levels in minipuberty correlate well with FSH-dependent adult semen parameters even in the normal male population (8). Testosterone, LH, and FSH can be rapidly and accurately measured in infancy in the appropriate time frame to screen for minipuberty or absence thereof. Molecular genetics will take longer. Replicating minipuberty by delivery of both LH and FSH or pulsed GnRH to stimulate LH and FSH secretion may lead to a profound improvement in the induction of spermatogenesis in adulthood. This should be initiated prior to the upregulation of androgen receptors on Sertoli cells, which occurs after age 4, thereby ensuring that gonadotrophins induce Sertoli cell proliferation, rather than maturation (9). Judging success for future fertility will take decades.

Orchidopexy is the appropriate management for those patients where the aetiology is not CHH or if failure of descent occurs after appropriate hormonal therapy. In our patient, the testes initially descended with hormonal therapy but the left subsequently retracted. Response to induction of spermatogenesis in adulthood was better in the right testis, having undergone surgical positional correction. This emphasises that hormonal therapy and orchidopexy address two different aspects of testicular reproductive health and are not mutually exclusive. However, to advise orchidopexy alone without qualification misses an opportunity to identify CHH.

Is CHH reversal an alternative explanation for our patient’s exceptional response to therapy? The testicular size of 6 mL at presentation at age 33 could suggest that. However, induction of minipuberty in infancy when the testis is sensitive to Sertoli cell proliferation increases testicular size by 2–5 fold (1). His clinical and genetic phenotype – micropenis and bilateral cryptorchidism at birth, azoospermia and undetectable gonadotrophins at age 33 (albeit in the setting of testosterone therapy), and the ANOS1 mutation – argue against such a rapid successful response to induction of spermatogenesis. In 308 patients with CHH, reversal was documented in 39 men, none of whom had bilateral cryptorchidism or an ANOS1 mutation (10). There is one case report of reversal of CHH in a man with ANOS1 mutation but without details of phenotypic features at birth (11). The argument for identifying CHH in infancy, to induce Sertoli cell proliferation with a view to enhancing response to induction of spermatogenesis in adulthood, still holds.

Our report has limitations as a result of the passage of time. The doctors who treated our patient in infancy are no longer with us – either deceased or retired – and their clinical notes are no longer obtainable. Recently developed hormonal markers, inhibin and AMH were not available at the time. However, the patient’s mother kept a diary of her son’s treatment. The passage of time is also the strength of this case report in that there is no other case in the literature describing long-term fertility results after pulsed GnRH therapy in an infant with CHH.

In conclusion, we propose that the slow response to induction of spermatogenesis in CHH is due to low Sertoli cell numbers, that is, in turn, a result of the absence of minipuberty and FSH-driven Sertoli cell proliferation in infancy. The clinical presentation of cryptorchidism at birth, with or without micropenis, should prompt screening for CHH by measurement of gonadotrophins and testosterone in the age window where minipuberty is expected. This will avoid missing the opportunity to identify CHH in the setting of cryptorchidism and can be followed by appropriate hormonal therapy with pulsatile GnRH to simulate minipuberty and increase Sertoli cell numbers. Appropriate hormonal management in infancy in these patients should have long-term benefits for fertility management as adults.

Declaration of interest

The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported.

Funding

The original research into pulsatile GnRH for cryptorchidism by Professor EJ Keogh received funding from the TVW Telethon Foundation, the Australian National Health and Medical Research Council, Ayerst Pty Ltd., The Raine Foundation, and Vickers (Australia) Pty Ltd. JDN has received a grant from the Endocrine Society of Australia for publication of this case report.

Patient consent

Written informed consent for the publication of their clinical details was obtained from the patient and his mother.

Patient’s perspective

I can’t remember anything of the initial treatment as a baby, so that was all beneficial. The treatment and connection at this time with doctors, specialists, and researchers, like Ted Keogh, was without a doubt the leading factor which set me up later in life for the successful treatment and management of my condition. Things would definitely have been completely different if I hadn’t received treatment or had only received it later in life. I think given the success and sheer luck that I had the opportunity for treatment has also given me the confidence to talk to others (friends/colleagues) around my condition and treatment.

Author contribution statement

All authors made individual contributions to authorship. BGAS, DMH, and JDN were involved in the clinical care and assessment of the patient. GBM was involved in the original pulsed GnRH program. All authors reviewed and approved the final draft.