Longitudinal gonadal function after bone marrow transplantation for acute lymphoblastic leukemia during childhood

Total body irradiation and high-dose chemotherapy, applied as a preparatory regimen for bone marrow transplantation (BMT) in children with acute lymphoblastic leukemia (ALL), are particularly hazardous to the gonads and, in addition, can impair hypothalamo pituitary-gonadal control. Longitudinal data on pubertal development and gonadal function in these patients are limited. Twenty-one ALL patients (15 males, 6 females) who had successfully undergone allogeneic BMT before puberty (age at BMT: 3.4-12.3 yr) were followed up in University Children's Hospital, Tübingen, Germany over 2 (minimum) to 14 (maximum) years. Tanner development scores, serum testosterone and estradiol, basal follicle-stimulating hormone (FSH) and luteinizing hormone (LH) were analyzed. During pubertal age, the levels of FSH and LH rose consecutively, resulting in noticeably elevated serum concentrations in 100% and 89%, respectively, of boys older than 14 years and in 75% and 75%, respectively, of girls older than 13 years. Nevertheless, pubertal development has been normal in all patients except in one boy and two girls who required substitution with sexual steroids, as timely puberty (i.e. boys < 14 years, girls < 13 years) did not start. In males with normal puberty, testosterone levels, however, were found to be low-normal. In conclusion, after BMT preceded by total body irradiation for childhood ALL, gonadal function is impaired. Even if normal pubertal development occurs, deficiencies in long-term endocrine function cannot be ruled out. In view of the high FSH levels, the prognosis for fertility is doubtful.     

Changes in hypothalamic-pituitary function following bone marrow transplantation in children

Patients who undergo bone marrow transplantation (BMT) frequently experience impaired pituitary function, but precise assessment using repeated provocative tests has not been described. We studied 32 children (16 boys) who had BMT after receiving preparative irradiation. Assessment of pituitary function was performed by infusing insulin, luteinizing hormone-releasing hormone (LHRH), and thyrotropin-releasing hormone (TRH) on several occasions at various intervals during the follow-up period. Serum free thyroxine (FT4) and thyrotropin (TSH) levels tended to be low during the early period following BMT. Serum FT4 concentrations reverted to the low-normal range 1 year after transplant, and eight of 29 patients had subnormal and delayed TSH response to TRH consecutively. No children showed overt hypothyroidism. Basal and peak serum gonadotropin levels in response to LHRH were elevated in the patients who had received transplant around the time of puberty. Leydig cell function assessed by human chorionic gonadotropin test was normal. Three girls experienced menarche, and one male patient fathered a normal boy 7 years after BMT. Pituitary-adrenal function and prolactin secretion were not affected. A high incidence of transient hypothyroidism which did not require replacement therapy and gonadal failure among pubertal children were observed. Shielding of gonads should be attempted, if possible, at the time of preparative irradiation to prevent resultant hypogonadism.     

Pubertal development in thalassaemic patients after allogenic bone marrow transplantation

To obtain further insight into gonadal function, a series of 50 prepubertal patients with -thalassaemia major (24 boys and 26 girls) aged from 12.6 to 18 years (mean 15 years) who had received a bone marrow transplantation (BMT) during childhood or the peripubertal period, at the age of 3.6–14.5 years (mean 10.8 years), were periodically re-evaluated at intervals of 6–12 months. The last evaluation was done 1–9 years (mean 4.2 years) after BMT. At each examination we measured height, pubertal stage, plasma gonadotrophins (LH and FSH) before and after the GnRH stimulation test (i.v.), sex steroids (total and free testosterone in males, and 17-oestradiol in females), serum ferritin and bone age. Fourty percent of patients entered or passed through puberty normally despite clinical and hormonal evidence of gonadal dysfunction in most of them. A correlation was not found between the pubertal stage and age at BMT, and no statistical difference between patients who did not enter into puberty and patients with spontaneous pubertal development was found in serum ferritin levels. Our data confirm that gonads in male and female thalassaemic patients are exposed to the cytotoxic effects of the preparative transplant regime with alkylating agents. In some patients absence of pubertal development was due to gonadotrophin insufficiency, probably secondary to previous iron overload. These findings emphasize the need for a vigilant long-term follow up study of thalassaemic patients who have had BMT.Part of this work has been presented at the 2nd International Symposium on Bone Marrow Transplantation in Thalassemia. Pesaro, Italy, 1992 and was supported by A.I.L., Pesaro, Italy.     

Pubertal development and growth after total-body irradiation and bone marrow transplantation for haematological malignancies

Pubertal development after total-body irradiation (TBI) was investigated in 40 children (21 boys) treated with allogeneic bone marrow transplantation (BMT) for haematological malignancies at a mean age of 11.3 years. The mean age at the last visit was 19.0 years. Twenty-five patients (15 boys) were prepubertal at BMT. Data on secondary sexual characteristics, the pituitary-gonadal axis and longitudinal growth were retrospectively collected from the medical records. In boys not receiving additional testicular irradiation (n = 19), penile growth and pubic hair development was normal and all had serum testosterone levels within the adult range. The majority of them, however, had incidental elevations of LH, suggesting minor Leydig cell damage. Testicular volume at last measurement was small (mean: 10.5 ml) and serum FSH levels were elevated in all boys, with normalisation in only one, suggesting severe impairment of reproductive gonadal function. Of the ten girls who received BMT before puberty, six had a spontaneous onset of puberty and menarche; the four other girls needed hormonal substitution therapy. Recovery of gonadal function after cessation of substitution was seen in one girl, who became pregnant but had a spontaneous abortion. Decrease in height SDS was seen in the majority of patients and was positively correlated with male gender and lower age at the time of BMT. Conclusion Careful monitoring of both gonadal function and growth after bone marrow transplantation and total body irradiation is warranted in order to detect disturbances early and ensure normal pubertal development in children treated for haematological malignancies. Received: 30 December 1998 / Accepted: 15 May 1999     

ENDOCRINOLOGICAL INVESTIGATION OF PITUITARY CONADAL AXIS IN THALASSEMIA MAJOR

Abstract A study of the pituitary gonadal axis was undertaken in 18 male patients with thalassemia major and 41 normal males, in order to define the cause of the sexual infantilism frequently seen in children affected by this illness. The plasma testosterone level was measured before as well as after stimulation by human chorionic gonadotropin (HCG). Serum gonadotropin level was also determined during prepubertal, pubertal and postpuberal age. Significant findings were an insufficient secretion of gonadotropins as well as low testosterone level in patients of pubertal and post-pubertal age. A normal response of testes to HCG stimulation was also observed.     

Ovarian function after successful bone marrow transplantation in postmenarcheal females

Ovarian function was followed serially in a group of six postmenarcheal females after successful bone marrow transplantation (BMT). The patients were between 13 9/12 and 22 6/12 (median 16 5/12) years of age at the time of BMT and were followed a median of 20 months (range 17-45 months) posttransplantation. Two subjects received short-term high-dose cyclophosphamide combined with single-dose total lymphoid irradiation (Group I), whereas the remaining four were treated with short-term, high-dose chemotherapy plus single-dose total body irradiation (Group II). Group II subjects also received combination chemotherapy prior to BMT. One subject from Group I continues to have regular menses and normal gonadotropin levels, 36 months post-BMT. The remaining five patients have demonstrated persistently elevated plasma concentrations of LH and FSH over a 17- to 45-month period of time. None of the four patients in Group II has menstruated since undergoing BMT. We conclude that single-dose radiation combined with short-term, high-dose chemotherapy results in profound ovarian damage in the majority of young women undergoing BMT.     

Analysis of insulin and cytokines during development using a multiplexed immunoassay: implications in pediatrics

IntroductionMultiplexed immunoassays allow the simultaneous determination of multiple parameters from minute biological samples. Our aim was to establish the normal values of cytokines and insulin during pubertal development, as well as their relationship with adrenal and gonadal steroids.Subjects and methodsSerum insulin, adiponectin, resistin, leptin, tumoral necrosis factor-α, interleukin-1β, interleukin-6 and interleukin-8 concentrations were studied in 147 healthy children (Tanner I, 18 males and 18 females; Tanner II, 17 males and 13 females; Tanner III and IV, 21 males and 19 females and Tanner V, 18 males and 23 females). The relationship of these parameters with free and total testosterone, estradiol, sex-hormone binding globulin, 17-hidroxyprogesterone, dehydroepiandrosterone sulphate, 3α-androstanediol glucuronide and Δ4-androstenedione levels were also analyzed.ResultsThe concentrations of insulin, resistin and leptin increased during development, with higher levels found in females. Adiponectin levels did not change, although higher concentrations were also observed in femalesthan in males. Interleukin-6 and 8 increased and interleukin-1β levels decreased throughout development, without any evidence of sexual dimorphism. There are good correlations between adiponectin and sex-hormone binding globulin, as well as between leptin and Δ4-androstenedione.ConclusionsChanges in these parameters seem to be related with adrenal and gonadal function. Pubertal stage and sex must be taken into consideration when these data are used.     

Gonadal development and function after immature testicular tissue banking as part of high-risk gonadotoxic treatment

Background

Experimental fertility preservation programs have been started to safeguard the future fertility of prepubertal and pubertal males requiring high-risk gonadotoxic treatment protocols. However, long-term follow-up studies evaluating the effects on their gonadal development and function related to the testicular biopsy procedure are rather limited.

Design

This two-center follow-up study (between 2002 and 2020) evaluated the gonadal development and function of a cohort of 59 prepubertal and pubertal males who have been offered immature testicular tissue banking (TTB) prior to conventional high-risk chemo- and/or radiotherapy (HR-C/R) or conditioning therapy before hematopoietic stem cell transplantation (CT-HSCT). The aim is to investigate the long-term impact of the testicular biopsy procedure and the high-risk gonadotoxic treatment. Testicular growth and the reproductive hormones luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone (T), and inhibin B (INHB) were analyzed after treatment completion, and compared between males accepting TTB and those refusing TTB (control) as well as between HR-C/R and CT-HSCT treatment protocols.

Results

Of the 59 prepubertal and pubertal males included, 25 were treated by HR-C/R and 34 required CT-HSCT. TTB was accepted for 39 males and refused for 20 males. Most patients were prepubertal at diagnosis (85%), at TTB (79%), and at treatment completion (76%), and pubertal or postpubertal at their last follow-up visit (66%). After 5.0 (1.0–13.0) years post treatment, most patients show normal testicular volumes (83%) and normal LH (89%), FSH (87%), T (87%), and INHB (79%) serum levels. The testicular biopsy procedure did not have an effect on testicular growth, LH, FSH, T, and INHB. Significantly more small postpubertal testicular volumes (p = .0278) and low INHB serum levels (p = .0130) were recorded after CT-HSCT, especially after myeloablative conditioning.

Conclusion

The clinical follow-up data demonstrate no effect related to the biopsy procedure, but a substantial risk for impaired gonadal development after high-risk gonadotoxic treatment, in particular myeloablative CT-HSCT. Longer follow-up studies with a larger study population are needed to confirm these preliminary findings.     

Gonadal dysfunction due to cis-platinum

Gonadal function was studied in 15 patients 12 pubertal or postpubertal, and three prepubertal, who had been treated during childhood for nonmetastatic osteosarcoma of the long bones by chemotherapy regimens that included cis-platinum and adriamycin. Of seven postpubertal female patients assessed (mean age at diagnosis 16.5 years), three were amenorrhoeic and showed evidence of ovarian damage with raised gonadotrophin levels and a low serum oestradiol concentration. One patient who had regular periods had a raised luteal-phase follicle-stimulating hormone (FSH) concentration suggestive of gonadal dysfunction. Severe oligospermia or reduced testicular volumes in the presence of raised gonadotrophin levels were observed in three of the five pubertal males (mean age at diagnosis 13.25 years). A reliable assessment of gonadal function was not possible in three male patients who remained prepubertal at the time of study. The median total dose of cis-platinum received by those patients with gonadal damage (median dose, 490 mg) was significantly higher than in those patients with normal gonadal function (median dose, 300 mg) (P = 0.01). In the boys the damage to the testes was primarily directed at the germinal epithelium. Leydig cell function was intact and the males progressed spontaneously through puberty. In the girls, unlike the boys, there was evidence of reversibility of gonadal damage with time. This is the first study to show gonadal dysfunction due to cis-platinum and adriamycin therapy in childhood.     

Prepubertal endocrine follow-up in subjects with Wilms' tumor

Twenty-three prepubertal subjects treated for Wilms' tumor (10 males and 13 females) were endocrinologically evaluated off therapy from 0.5 to 4.08 years. They were divided into two groups: 11 subjects (6M, 5F) who had received chemotherapy only (group 1) and 12 (4M, 8F) who had in addition received abdominal radiation (1,500-3,000 rads) (group 2). Follicle-stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), thyroid-stimulating hormone (TSH), free thyroxine (FT4), free tri-iodo thyronine (FT3), testosterone (T), estradiol-17 beta (E2), and cortisol (F) were measured by radioimmunoassay (RIA). Plasma levels of TSH, PRL, FT4, FT3, and F were normal in both groups, as were FSH, LH, T, and E2 in group 1. In group 2, female subjects showed FSH levels significantly higher than controls, while LH and E2 were normal; male subjects showed significantly higher LH levels, while FSH and T levels were normal. These results indicate that in the treatment protocol used by us for Wilms' tumor (WT), chemotherapy does not affect endocrine function, whereas abdominal radiation seems to damage gonadal function directly. The present findings indicate that gonadal damage may be revealed in WT before puberty not only in females, as has been previously reported, but also in male subjects.     

Normal long-term parathyroid function after autologous bone marrow transplantation in children

Parathyroid function was recently reported to be affected in more than one-third of pediatric BMT patients conditioned without irradiation. Our aim was to describe parathyroid function in children with malignant hematological disease after autologous BMT with and without TBI. PTH, albumin-corrected serum calcium, and serum phosphate were analyzed in 35 children followed for six months to nine yr after BMT. Twelve patients were conditioned with chemotherapy alone, and 23 patients received TBI as well. In the TBI group, 11 patients had previously received additional CRT. We found normal levels of PTH in children post-BMT, with the exception of four patients (11%) who showed transient PTH elevation during the first year of follow-up, There was no difference between those who had received irradiation and those who had not. Serum calcium was unchanged after BMT. An age-corrected quotient of serum phosphate decreased slightly. Renal function which was normal before BMT decreased slightly in both groups after BMT, but was within the normal range. Parathyroid function was found to be normal during the time frame of this study, irrespective of whether irradiation had been given.     

Diagnosis,investigation and treatment of delayed puberty in children

Delayed puberty is defined as lack of secondary sexual characteristics from the age of 13 years in females and 14 years in males. The most common cause is constitutional delay in growth and puberty, which occurs mainly in boys. Thereafter, pubertal delay can be classified according to circulating levels of luteinzing hormone and follicle-stimulating hormone. CNS abnormalities result in hypogonadotrophic hypogonadism and gonadal failure causes hypergonadotrophic hypogonadism. New molecular defects that regulate gonadal function and cause pubertal abnormalities continue to be identified.     

Endocrine complications of high-dose therapy with stem cell transplantation

Abstract:  Evaluations of endocrine function following hematopoietic cell transplantation demonstrate that the endocrine function abnormalities observed are related to the type of transplant preparative regimen received. Children given high dose cyclophosphamide (CY) only have normal thyroid function, normal growth and development. Children who received a busulfan (BU) plus CY preparative regimen usually have normal thyroid function, normal prepubertal growth, delayed or absent pubertal development, and blunted post-pubertal growth. Recipients of preparative regimens containing total body irradiation may be anticipated to have some thyroid dysfunction, impaired growth rates and delayed or absent pubertal development. Post-pubertal teens and young adults are likely to have gonadal function recover if they received a preparative regimen with CY only but are likely to have primary gonadal failure if they received a preparative regimen with BU or total body irradiation. Individuals whose gonadal function becomes normal have become parents of normal children. All patients who receive a marrow transplant should be followed long-term for development of endocrine function abnormalities.     

Spontaneous and GnRH-provoked gonadotropin secretion and testosterone response to human chorionic gonadotropin in adolescent boys with thalassaemia major and delayed puberty

To elucidate whether the cause of sexual maturation arrest in thalassaemia is of gonadal or pituitary etiology, 10 males with thalassaemia and delayed puberty and 10 with constitutional delay of growth and pubertal maturation (CSS) were extensively studied. Their spontaneous nocturnal gonadotropin secretion and gonadotropin response to intravenous 100 micrograms gonadotropin-releasing hormone (GnRH) were evaluated. Circulating testosterone concentration and clinical response were evaluated after 3 days, 4 weeks and 6 months of intramuscular administration of human chorionic gonadotropin (HCG) (2500 U/m2/dose). Thalassaemic boys had significantly lower circulating concentrations of testosterone compared to those with constitutional delay of growth and sexual maturation (CSS) at the same pubertal stage. Short- and long-term testosterone response to administrations of HCG was markedly decreased in thalassaemic boys. After 6 months of HCG administration 50 per cent (5/10) of the boys did not show significant testicular enlargement or genital changes. Despite the low circulating concentrations of testosterone, none of the patients had high basal or exaggerated gonadotropin response to gonadotropin releasing hormone (GnRH) stimulation. Luteinizing hormone (LH) peak responses to GnRH were significantly lower as compared to controls. Follicle-stimulating hormone (FSH) peak responses to GnRH did not differ among the two study groups. The mean nocturnal LH and FSH secretion was significantly decreased in all thalassaemic boys as compared to boys with CSS at the same pubertal stage (testicular volume). These data proved that hypogonadotropic hypogonadism is the main cause of delayed/failed puberty in adolescents with thalassaemia major. MRI studies revealed complete empty sella (n = 5), marked diminution of the pituitary size (n = 5), thinning of the pituitary stalk (n = 3) with its posterior displacement (n = 2), and evidence of iron deposition in the pituitary gland and midbrain (n = 8) in thalassaemic patients, denoting a high incidence of structural abnormalities (atrophy) of the pituitary gland. Moreover, in many of the thalassaemic boys, the defective testosterone response to long-term (6 months) HCG therapy denoted significant testicular atrophy and/or failure secondary to siderosis. It appears that testosterone replacement might be superior to HCG therapy in these patients. This therapy should be introduced at the proper time in these hypogonadal patients to induce their sexual development and to support their linear growth spurt and bone mineral accretion.     

Pituitary-gonadal function in Klinefelter syndrome before and during puberty

Serum concentrations of follicle-stimulating hormone, luteinizing hormone, testosterone, and estradiol were determined at intervals before and during puberty in 40 individuals with Klinefelter syndrome (47,XXY karyotype), of whom 27 had been detected in neonatal cytogenetic screening programs. Prior to the appearance of secondary sexual changes, basal serum hormone concentrations and acute responses to stimulation with gonadotropin-releasing hormone and human chorionic gonadotropin were normal. The timing of the onset of clinical puberty was normal. Early pubertal boys showed initial testicular growth and normal serum testosterone levels, while serum follicle-stimulating hormone and estradiol concentrations were significantly elevated. By midpuberty, the Klinefelter subjects were uniformly hypergonadotropic and their testicular growth had ceased. Serum testosterone concentrations after age 15 remained in the low-normal adult range. Serum estradiol levels remained high, irrespective of the presence or absence of gynecomastia. Exaggerated responses to gonadotropin-releasing hormone are seen in pubertal subjects with elevated basal gonadotropin values.     

Pubertal maturation in girls treated for childhood acute leukaemia

Eleven girlds treated during childhood for acute leukaemia were followed up during their pubertal development. At each examination weight, height, pubertal stage, FSH, LH, oestradiol, testosterone, androstenedione and dehydroepiandrosterone sulphate levels were evaluated. Clinical and endocrinological studies were performed according to age and pubertal stage and compared to those of healthy girls matched for age and pubertal stage. Results showed that pubertal maturation and gonadal function were not affected by oncotherapy; however menarche was attained earlier. Early menarche was explained by the overweight of treated girls during early puberty. No evidence of early hypothalamic activation was found, but endocrine patterns showed a faster hypothalamopituitary-ovarian axis maturation in patients than controls. Cranial irradiation showed no correlation with pubertal onset and age at which menarche was attained. Adolescent menstrual and endocrine patterns were normal.     

Children with sickle cell disease: growth and gonadal function after hematopoietic stem cell transplantation

The aim of this study is to describe the growth, pubertal development, and gonadal function of a cohort of 30 sickle cell disease children who underwent bone marrow transplantation. They all received the standard pretransplant conditioning regimen of busulfan (14 or 16 mg/kg) and cyclophosphamide (200 mg/kg). Growth was normal both before and after transplant. Seven out of 10 girls had severe ovarian failure and requirement for estrogen replacement. Three out of 10 girls recovered some ovarian function posttransplant, with spontaneous pubertal development, menses, and 1 successful normal pregnancy. Follicle-stimulating hormone (FSH) serum levels were very high during spontaneous puberty and slowly normalized thereafter in these 3 patients. The 3 girls with ovarian function recovery differed from the 7 others by the lower busulphan dose of the conditioning regimen they received (14 rather than 16 mg/kg). All boys showed spontaneous pubertal development. However, most of them had small testis and elevated serum FSH levels, reflecting germinal epithelium damage. Testosterone level was low normal and luteinizing hormone elevated, reflecting Leydig cell insufficiency. In conclusion, 7/10 girls had complete gonadal failure and most of the boys had spontaneous puberty but germinal epithelial failure. Serum FSH levels showed important variations over time in the same patient.     

Long-term complications following bone marrow transplantation in children

Abstract Seventeen children who underwent bone marrow transplantation (BMT) between 1975 and 1985 and survived for more than 2 years were evaluated for growth and development. The patients had a follow up of 2.1-13.1 years. Prior to transplant, children with malignancy had received multi-agent chemotherapy and nine had also received central nervous system irradiation. Transplant preparation for malignancy (group 1; n = 13) included high-dose cyclophosphamide (CPA) 120–200 mg/kg and total body irradiation (TBI) 10–13.2 Gy, whereas conditioning for non-malignant disorders (group 2; n = 4) included high-dose CPA 200 mg/kg with or without busulphan. Patients in group 1 showed a steady decline in height velocity following initial chemotherapy and cranial irradiation and the decline was even greater following BMT. Growth hormone (GH) deficiency developed in eight of nine children tested, hypergonadotrophic hypogonadism developed in 11 who reached puberty, thyroid hormone abnormalities were encountered in four out of 10 tested and 11 of 13 developed cataracts. Patients in group 2 did not show decline in linear growth rate, thyroid hormone abnormalities or cataracts after BMT. The only child tested had normal GH levels and the two patients who reached puberty showed delayed but complete gonadal recovery. Our data demonstrate that TBI leads to significant late effects on growth and gonadal function. Contrary to previous reports, a high incidence of cataract formation is observed after fractionated TBI. Conditioning regimens without TBI should be considered in children undergoing BMT.     

Gonadal function after testicular radiation for acute lymphoblastic leukaemia.

Pubertal maturation, growth, and gonadal function were assessed in 13 boys with acute lymphoblastic leukaemia who had received direct testicular irradiation three to nine years earlier as treatment for testicular relapse or prophylaxis against this complication. Six boys had reached Tanner stage III-V puberty, five of whom had normal growth velocities and bone ages equivalent to chronological age. One boy exhibited maturational arrest on entering stage IV. The remaining seven children (54%) showed evidence of complete pubertal delay or arrested development in stage II, with absence of the pubertal growth spurt and often with delayed bone age. Basal gonadotrophins were abnormally high in all 13 boys, and those with delayed puberty had prepubertal concentrations of testosterone. Testicular irradiation given before puberty causes permanent Leydig cell damage in a high proportion of subjects, necessitating testosterone supplementation. The extent of damage may be related to the age at which radiation is delivered.     

Gonadal function after combination chemotherapy for Hodgkin's disease in childhood.

The effect of quadruple chemotherapy (mustine, vincristine, procarbazine, and prednisolone) on gonadal function was investigated in 15 males and 2 females treated for Hodgkin''s disease during childhood. The 2 females have regular menstrual cycles with evidence of ovulation in one. Twelve of the males have shown normal progression of pubertal development since completing their treatment. Nine out of 10 late pubertal or adult subjects had small testes but only one developed gynaecomastia. All 4 prepubertal subjects had normal basal and peak gonadotrophin responses to luteinising hormone-releasing hormone. Nine of the 12 subjects studied during puberty or adulthood had either an increased basal serum follicle-stimulating hormone (FSH) level or an exaggerated FSH response to luteinising hormone-releasing hormone. Each of the 6 males who provided semen for analysis was azoospermic after an interval of between 2.4 and 8 (mean 5.3) years after completion of treatment. We conclude that severe testicular damage is common after treatment with mustine, vincristine, procarbazine, and prednisolone in childhood. The germinal epithelium is particularly vulnerable and the resultant azoospermia is likely to be irreversible. The Leydig cells are less susceptible to cytotoxic-induced damage. Pubertal development is normal and there is no indication for androgen replacement therapy.