Serum inhibin B,FSH, LH and testosterone levels before and after human chorionic gonadotropin stimulation in prepubertal boys with cryptorchidism

BACKGROUND: Several studies have indicated that cryptorchidism is associated with degenerative changes in both Sertoli cells and germ cells. The gonadal peptide hormone inhibin B reflects Sertoli cell function. Low inhibin B levels are found in a large portion of formerly cryptorchid men who show compromised seminiferous tubule function. It is not known if inhibin B can be used to demonstrate early damage of seminiferous tubules in prepubertal boys with cryptorchidism. METHODS: We investigated the relationship between serum levels of inhibin B, testosterone, FSH and LH in 62 prepubertal boys with uni- and bilateral cryptorchidism. Furthermore, we investigated the changes in serum levels of inhibin B and the corresponding changes in serum levels of FSH, LH and testosterone during a short course (3 weeks) of human chorionic gonadotropin (hCG) injections in 18 of these cryptorchid boys. RESULTS: In the 62 prepubertal boys with uni- or bilateral cryptorchidism there were no significant differences in baseline levels (median and range) of inhibin B (88 (20-195) pg/ml vs 78 (35-182) pg/ml; not significant), LH (0.08 (<0.05-0.99) IU/l vs 0.06 (<0.05-1.61) IU/l; not significant) and FSH (0.60 (0.08-3.73) IU/l vs 0.85 (0.25-2.55); not significant) compared with 156 healthy prepubertal boys, and there were no differences in hormonal levels between boys with uni- or bilateral cryptorchidism. There was no correlation between baseline levels of inhibin B and FSH. In boys younger than 9 years, we found no correlation between baseline levels of inhibin B and LH whereas, in boys older than 9 years, baseline levels of inhibin B were positively correlated to baseline LH (Spearman rank correlation coefficient ((R(s))=0.58, P=0.03). Treatment with hCG (1500 IU intramuscularly twice weekly for 3 weeks) resulted in descensus of testes in 9 out of 18 patients. In all boys but one, irrespective of age, hCG induced a marked increase in testosterone into the adult range (from undetectable to 21.8 (7.0-35.4) nmol/l; P<0.001) and completely suppressed FSH and LH levels. Serum levels of inhibin B increased significantly from 116 (50-195) pg/ml to 147 (94-248) pg/ml (P<0.05), but not uniformly. The increase in serum levels of inhibin B was inversely correlated to baseline inhibin B (Rs=-0.52, P=0.03) and baseline FSH (R(s)=-0.59, P<0.01). CONCLUSIONS: We therefore suggest that, in the prepubertal testes, inhibin B is secreted from the prepubertal Sertoli cells following hCG, whereas early pubertal testes with more differentiated Sertoli cells are not able to secrete inhibin B in response to hCG stimulation, perhaps due to lack of germ cell-derived betaB-subunits. We found (a) normal inhibin B levels in prepubertal boys with uni- or bilateral cryptorchidism, (b) that hCG stimulated testosterone markedly and suppressed FSH and LH levels and (c) that hCG treatment stimulated inhibin B levels in the youngest cryptorchid boys. In the oldest prepubertal boys no hCG-induced changes in inhibin B were shown.     

Multiple forms of hypogonadism of central, peripheral or combined origin in males with Prader-Willi syndrome

Background Hypogonadism in Prader–Willi syndrome (PWS) is generally attributed to hypothalamic dysfunction or to primary gonadal defect, but pathophysiology is still unclear. Objectives To investigate the aetiology of hypothalamic–pituitary–gonadal axis dysfunction in PWS males. Methods Clinical examination and blood sampling for luteinizing hormone (LH), follicle‐stimulating hormone (FSH), testosterone, inhibin B and sexhormone–binding globulin (SHBG) were performed in 34 PWS patients, age 5·1–42·7 years, and in 125 healthy males of same age range. All participants were divided into two groups : < or ≥13·5 years. Results Pubertal PWS patients showed an arrest of pubertal development. Patients <13·5 years had normal LH, FSH, testosterone and 7/10 had low inhibin B. Among those ≥13·5 years, 8/24 patients had normal LH and testosterone, high FSH and low inhibin B. 5/24 had low FSH, LH, testosterone and inhibin B; one showed normal LH and FSH despite low testosterone and inhibin B; 4/24 had low testosterone and LH but normal FSH despite low inhibin B; 6/24 showed high FSH, low inhibin B and normal LH despite low testosterone. Compared with controls, patients <13·5 years had lower LH, inhibin B, similar FSH, testosterone, SHBG levels and testicular volume; those ≥13·5 years had smaller testicular volume, near‐significantly lower LH, testosterone, SHBG, inhibin B and higher FSH. Conclusion PWS patients display heterogeneity of hypogonadism: (i) hypogonadotropic hypogonadism of central origin for LH and/or FSH; (ii) early primary testicular dysfunction (Sertoli cells damage); and (iii) a combined hypogonadism (testicular origin for FSH‐inhibin B axis and central origin for LH‐T axis).     

Changes in serum inhibin B during normal male puberty

OBJECTIVE: In adult men, inhibin B (InhB) regulates FSH secretion by a negative feedback. The aims of this study were to evaluate the changes of InhB during puberty in the male and the relationship between InhB and FSH, LH, testosterone and testicular volume. DESIGN: Cross-sectional study. METHODS: InhB was measured using a two-site ELISA in 100 healthy boys subdivided by their pubertal development according to Tanner into five groups of 20. RESULTS: During puberty we observed an increase of InhB level (G1 = 84.3 pg/ml, G3 = 132.2 pg/ml, G5 = 206.1 pg/ml). In G1, InhB correlated positively with FSH (P = 0.0001), LH (P = 0.005), testosterone (P = 0.001) and testicular volume (P = 0.007); in G5, InhB correlated inversely with FSH (P = 0.001) and LH (P = 0.045) and directly with testicular volume (P = 0.013). The multivariate analysis demonstrated that: in G1, FSH is the most important, and testosterone the second most significant, stimulus for InhB increase; in G2 only FSH has a positive effect on InhB variation; in G3 only mean testicular volume fits the model (G1-G3: InhB dependent variable); considering the FSH dependent variable, in G4, InhB is the most important stimulus for FSH decrease and mean testicular volume is a secondary directly proportional variable; in G5, only InhB shows a significant inverse relationship with FSH. CONCLUSIONS: During puberty there is a regular increase of InhB. In the first phases of gonadal maturation, InhB and FSH correlate positively, while in mid-late stages the relationship is inverse. We found that in mid-puberty (G3-G4), the serum concentration of InhB increases, as its inverse relationship with FSH is being established and hence spermatogenesis.     

Altered serum profile of inhibin B, Pro-alphaC and anti-Müllerian hormone in prepubertal and pubertal boys with varicocele

OBJECTIVE: Anti-Müllerian hormone (AMH) and inhibin B are reliable markers of Sertoli cell function. The aim of the present study was to assess the functional state of Sertoli cells in order to detect early changes in the testicular function of prepubertal and pubertal patients with untreated grade II or III varicocele. DESIGN AND PATIENTS: Seven prepubertal and 55 pubertal boys with untreated grade II or III varicocele were studied. Seven prepubertal and 43 pubertal normal boys were considered as controls. MEASUREMENTS: Serum levels of gonadotrophins, testosterone, inhibin B and Pro-alphaC and AMH were determined by time-resolved immunofluorometric assays, radioimmunoassay (RIA) and specific enzyme-linked immunosorbent assays (ELISAs), respectively. RESULTS: Inhibin B and Pro-alphaC serum levels were higher in prepubertal patients with varicocele than in controls (P < 0.001). No further increment in inhibin B and Pro-alphaC levels was observed in pubertal patients with varicocele. Higher levels of AMH were found in patients in Tanner stages I, III, IV and V when compared to normal boys by Tanner stage (P < 0.05, P < 0.01, P < 0.01, P < 0.001, respectively). The direct correlation found in normal boys between inhibin B levels and LH, testosterone and testicular volume was not observed in patients with varicocele. CONCLUSIONS: The altered serum profile of gonadal hormones observed in untreated prepubertal and pubertal patients with varicocele may indicate an early abnormal regulation of the seminiferous epithelium function.     

Treatment of gonadotropin-deficient boys with recombinant human FSH: long-term observation and outcome

BACKGROUND: Boys with prepubertal onset of hypogonadotropic hypogonadism (HH) are at a risk of poor testis growth and impaired spermatogenesis. One potential cause for this is deficient proliferation of immature Sertoli cells before and during puberty due to the absence of FSH. OBJECTIVE: To evaluate the effects of recombinant human FSH (r-hFSH) and human chorionicgonadotropin (hCG) on testicular function and pubertal development in boys with prepubertal onset of HH. DESIGN: Retrospective clinical study. SETTING: Two university central hospitals, pediatric referral endocrinology outpatient clinics. PATIENTS: Fourteen boys (aged, 9.9-17.7 years) with prepubertal (testicular volume (TV) <3 ml) onset of HH (idiopathic HH, n=2; Kallman syndrome, n=2; idiopathic panhypopituitarism, n=4; organic panhypopituitarism, n=6). INTERVENTION: Treatment with r-hFSH alone (2 mo-2.8 years) prior to induction of puberty with the combination of FSH and hCG. Main outcome measures: Progression of puberty, change in serum inhibin B, spermatogenesis. RESULTS: r-hFSH alone increased testicular volume twofold, from 0.9+/-0.6 ml (mean+/-s.d.) to 1.8 +/- 1.1 ml (P<0.005), and serum inhibin B threefold, from 27+/-14 to 80+/-57 pg/ml (P<0.01). Three boys with an apparent absence of postnatal hypothalamic-pituitary-testicular axis activation displayed attenuated inhibin B responses to long-term (>or=1 year) r-hFSH (P<0.01). Further significant increase in both TVand inhibin B occurred with induction of puberty with FSH and hCG (P<0.001). Seven boys provided semen samples: one had azoospermia, and others displayed a maximal sperm count range from 2.9 to 92 million/ml (median 8.5 million/ml). CONCLUSIONS: (i) r-hFSH induces prepubertal testis growth and increases circulating inhibin B levels, findings suggesting proliferation of immature Sertoli cells. (ii) Puberty was successfully induced with hCG and r-hFSH following r-hFSH priming. (iii) Inhibin B appears useful for monitoring spermatogenetic activity in boys treated with hCG. (iv) Despite the extremely small initial testis volume, six out of seven patients (86%) primed with r-hFSH displayed sperm in the ejaculate suggesting beneficial effect of r-hFSH priming on testicular function later in life.     

Clinical significance of elevated level of serum antithyroglobulin antibody in patients with differentiated thyroid cancer after thyroid ablation

OBJECTIVE: Inhibin B in males is produced principally by Sertoli cells under the influence of FSH and is thought to have a role in feedback regulation of FSH. The aims of our study were to investigate how inhibin B changes from birth to late adolescence in boys, to derive reference data and to explore its relation with pubertal stage, FSH and testosterone. DESIGN AND SUBJECTS: Blood samples were collected from (i) 366 boys aged 0--18 years to obtain age-related reference data; (ii) 195 boys who had full pubertal staging; and (iii) a cohort of 15 boys studied longitudinally as they approached and entered early puberty. MEASUREMENTS: Dimeric inhibin B was measured by double antibody enzyme-linked immunosorbent assay (ELISA), FSH by immunoradiometric assay (IRA) and testosterone by an extraction radioimmunoassay. RESULTS: Inhibin B was high in infant boys, decreased gradually to a nadir at 6--10 years of age, then increased rapidly in early adolescence to reach a new plateau at 12--17 years. It was detectable in all samples. Age-related reference ranges and data for calculation of SD scores are presented. In prepubertal boys, inhibin B correlated positively with age (P < 0.001), but not with FSH. Inhibin B increased progressively from pubertal stages G1 to G3 but then decreased slightly at stages G4 to G5 (P less-than-or-equal 0.01). At stage G2, inhibin B correlated positively with testosterone (P < 0.01) but not with FSH. From stage G3 onwards, inhibin B correlated inversely with FSH (P < 0.01) but lost its relationship with testosterone. In the cohort of boys studied longitudinally, inhibin B increased progressively prior to pubertal onset and further on entry into early clinical puberty (P < 0.05). Testosterone also increased over this period (P < 0.05) but FSH showed no significant change. CONCLUSIONS: The two peaks of inhibin B during infancy and early puberty appear to reflect the two periods of Sertoli cell proliferation in normal human males. During mid-childhood, a relatively constant amount of inhibin B is secreted constitutively. The early FSH-independent increase in inhibin B that precedes clinical puberty and continues to stage G2 may be stimulated by testosterone or other factors from Leydig cells. The inverse relationship between inhibin B and FSH that subsequently develops from mid-puberty onwards is consistent with the establishment of a negative feedback loop at this time.     

Abnormal puberty in paediatric Cushing's disease: relationship with adrenal androgen, sex hormone binding globulin and gonadotrophin concentrations

OBJECTIVE: Paediatric Cushing's disease is frequently associated with abnormal puberty. We addressed the hypothesis that prepubertal patients show excessive virilization and pubertal patients show suppression of LH and FSH secretion. DESIGN AND MEASUREMENTS: Serum androstenedione (A4), dehydroepiandrosterone sulphate (DHEAS), testosterone (T), and sex hormone binding globulin (SHBG) were determined at diagnosis and converted to standard deviation scores. LH, FSH concentrations were also determined. Severity of CD was assessed from the sleeping midnight cortisol concentration. Puberty was staged and excessive virilization defined as advance in pubic hair stage for breast stage or testicular volume (TV). PATIENTS: Twenty-seven CD patients (17 male, 10 female), median age 13.4 years (range 5.9-17.8) were studied. RESULTS: In the CD group as a whole, A4, DHEAS, T standard deviation scores (SDS) values were normal. SHBG SDS values (n = 19) were low (median -1.93, -4.32-0.86) correlating with BMI (r = -0.49). A4, DHEAS, T, SHBG, LH and FSH did not correlate with midnight cortisol, but A4 and T SDS correlated with ACTH at 09.00 h (both r = 0.51). Thirteen patients (11 male, 2 female) had excessive virilization with increased A4 (P = 0.033), DHEAS (P = 0.008), testosterone (P = 0.033) and decreased SHBG (P = 0.004) compared with subjects without excessive virilization. Pubertal boys (TV > or = 4 ml) (n = 7) and girls (breasts > or = stage 2) (n = 8) had low median LH and FSH. Boys had an LH concentration of 1.2 mU/l (0.3-3.5), FSH, 0.9 mU/l (0.2-6.4) and median T SDS, -1.95 (-3.8-4.65), while girls had an LH concentration of 1 mU/l (0.3-7.4). CONCLUSIONS: Many patients had abnormal puberty and excessive virilization associated with increased adrenal androgens and decreased SHBG. Pubertal patients had low LH and FSH suggesting impaired pituitary-gonadal axis function.     

Pubertal development in obese children and adolescents

OBJECTIVE: To investigate clinical and laboratory markers of pubertal development in a large sample of obese children and adolescents. METHODS: Analysis of parameters of sexual maturation in 1232 obese individuals (582 boys) aged 6-18 years (mean 13.0+/-2.42 years). Clinical evaluation of pubertal stage and determination of bone age in a subset (227 patients). RESULTS: Mean Height--standard deviation scores (height-SDS) was positive during childhood and reached zero approximately at age 14 years followed by a turn to negative mean height-SDS in both genders. Accordingly, bone age was accelerated until age 14. No significant differences in average time points of occurrence of pubic hair stages PH 2 to PH 4 in boys and PH 2 to PH 5 in girls were observed as compared to references of the First Zurich Longitudinal Study. In girls, breast stage B 3 was reached earlier (11.6 vs 12.2 years, P=0.03). In boys, mean volume of testis revealed no significant deviation from reference. Mean dehydroepiandrosterone sulfate (DHEAS) levels were elevated in boys (within age ranges 8-10 years and 12-16 years, P<0.02) and in girls (within age ranges 6-8 years and 12-18 years, P<0.005) and mean testosterone levels in boys >12 years were lower as compared to reference ranges (all P-values <0.0001). CONCLUSION: The study data suggest normal development of pubarche and gonadarche in obese German boys and normal timing of pubarche in girls. Breast development in obese girls seems to be slightly advanced. In obese boys, an obvious dissociation of clinical and laboratory parameters of pubertal development was observed. Despite significantly increased height-SDS and increased DHEAS levels, gonadal development was normal and testosterone levels were decreased. Elevated DHEAS levels in both genders may contribute to the acceleration of bone maturation, a lower final body height and could increase cardiovascular risk.     

Secretion of inhibin B by human prepubertal testicular cells in culture

OBJECTIVE: Inhibin B is a secretory product of Sertoli cells of the human testis. It has been reported that serum levels of inhibin B in infant boys, peaking at 3 months of age, exceed levels in adult men. The aim of this study was to evaluate inhibin B secretion in primary prepubertal mixed testicular cell cultures, prepared from testes collected at necropsy. DESIGN AND METHODS: Cell cultures were divided into three age groups on the basis of differences in testicular histology: group 1 (n = 7), 1- to 10-day-old newborns, group 2 (n = 7), 1- to 9-month-old infants, and group 3 (n = 8), 12- to 84-month-old children. Cells were maintained in culture for 6 days, harvested and counted. In some samples, during the last 4 days, cells were stimulated with 10ng/ml highly purified human (h) LH (n = 9), 2 ng/ml recombinant human (rh) FSH (n = 9) or 50 ng/ml rhGH (n = 4). On day 6, the secretion of inhibin B and testosterone into the medium was estimated in triplicate. Inhibin B was determined by ELISA and testosterone by RIA. RESULTS: Median (range) inhibin B secretion was 465 (225-1007), 275 (107-298), and 58 (15-184) pg/million cells.24h in groups 1, 2 and 3 respectively. A logarithmic transformation of these values was performed to normalize data. Mean+/-s.d. of transformed inhibin B secretion in group 1 was significantly higher than in group 2 or 3 (P<0.005) and the values for groups 1 and 2 were significantly higher than that for group 3 (P< 0.005). No significant correlation between testosterone and inhibin B secretion into the medium was found when the 22 culture samples were analyzed as a whole. Inhibin B secretion was significantly increased after stimulation with highly purified hLH, rhFSH and rhGH (P < 0.05) and a significant positive correlation between inhibin B and testosterone was found under both hLH and rhFSH stimulation. CONCLUSIONS: It is concluded that cells collected from newborns have the highest capacity to secrete inhibin B in vitro, and that this capacity decreases with age during the first years of life. Since no data are available on serum inhibin levels in newborns, it is possible that concentrations at 3 months of age do not represent a post-natal peak but a declining level of high newborn values. As expected, FSH stimulated inhibin B secretion in culture. LH stimulation was probably mediated by paracrine factors secreted by interstitial cells. Finally, our results add new evidence of the involvement of GH in testicular maturation.     

Basal inhibin B and the testosterone response to human chorionic gonadotropin correlate in prepubertal boys

During childhood, the quiescent phase of testicular activity, the hCG stimulation test is widely used to evaluate testicular function. Inhibin B, a gonadal peptide regulating FSH secretion, is an established marker of Sertoli cell function and spermatogenesis in adults. In contrast to the other hormones of the hypothalamo-pituitary-gonadal axis, inhibin B is also secreted in detectable amounts during childhood. The aim of this study was to determine whether basal inhibin B levels are able to predict prepubertal testicular function, so as to avoid a stimulation test. Inhibin B and testosterone before and after hCG stimulation were measured in 54 male children with various testicular disorders by an immunoassay specific for inhibin B. Basal inhibin B was compared to the testosterone increase after hCG. Inhibin B and the hCG-induced testosterone increment correlated strongly (r = 0.84; P<0.0001). Patients with anorchia were clearly distinguishable from those with abdominal testes, having undetectable (inhibin B, <15 pg/mL) respective normal inhibin B levels for age. Inhibin B and the testosterone response to hCG were low in boys with testicular damage (delayed diagnosis of cryptorchidism; after testicular torsion) and in patients with gonadal dysgenesis, but were normal or increased in children with androgen insensitivity syndrome. We conclude that basal inhibin B predicts the testosterone response to hCG in boys and therefore gives reliable information about both the presence and function of the testes. The diagnostic procedure in cryptorchidism may be reduced to a single inhibin B measurement. Furthermore, inhibin B levels show specific alterations in patients with sexual ambiguity, adding a valuable diagnostic tool to the complex differential diagnosis of male pseudohermaphroditism.     

Early postnatal treatment of hypogonadotropic hypogonadism with recombinant human FSH and LH.

BACKGROUND: Patients with hypogonadotropic hypogonadism may be diagnosed shortly after birth because of micropenis and cryptorchidism, combined with subnormal LH and FSH concentrations during the postnatal period. OBJECTIVE: To investigate whether treating these patients with gonadotropins postnatally, to mimic the physiological development, would improve testicular growth and fertility potential later in life. DESIGN: Our patient presented with micropenis. Serum hormone concentrations were measured monthly after delivery: LH and testosterone were undetectable, and FSH and inhibin B were below the normal range (0.05-0.17 IU/l and 79-112 pg/ml respectively). METHODS: From 7.9 to 13.7 months of age, the patient was treated with recombinant human LH and FSH in doses of 20 and 21.3 IU s.c. twice weekly respectively. RESULTS: During treatment concentrations of LH, FSH, inhibin B and estradiol increased to values within normal limits (0.7-1.88 IU/l, 0.17-3.24 IU/l, 121-268 pg/ml and 40-55 pmol/l respectively), whereas serum testosterone remained undetectable. Penile length increased from 1.6 to 2.4 cm and testicular volume, assessed by ultrasound, increased by 170%. No significant adverse events were observed. CONCLUSIONS: Gonadotropin treatment in an infant with hypogonadotropic hypogonadism succeeded in inducing an increase in inhibin B and testicular growth.     

The effect of distinct activating mutations of the luteinizing hormone receptor gene on the pituitary-gonadal axis in both sexes

OBJECTIVE: Familial or sporadic male-limited precocious puberty is a distinct and unusual gonadotrophin-independent form of sexual precocity caused by constitutively activating mutations of the luteinizing hormone receptor (LHR). In the present study, we evaluated the effect of known activating mutations at different sites of the LHR gene on the pituitary-gonadal axis in both sexes. PATIENTS: Four unrelated Brazilian boys (I-IV) with gonadotrophin-independent precocious puberty and two asymptomatic females (V-VI), a sister and mother of two of the affected boys, were studied. Patients I, II and V carried the Ala568Val mutation located at the third intracellular loop of the LHR. Patient III carried the Leu457Arg mutation at the third transmembrane helix, and patients IV and VI carried the Thr577Ile mutation at the sixth transmembrane helix of the LHR. MEASUREMENTS: Serum levels of LH, FSH, testosterone, and oestradiol under basal and GnRH-stimulated conditions were determined in all patients. Testosterone levels were also measured after a hCG stimulation test in patient III. RESULTS: Basal LH and FSH levels were prepubertal in all boys studied. The GnRH-stimulated serum LH and FSH levels were prepubertal in three boys (I, II and IV), whereas patient III showed totally suppressed LH and FSH levels at ages 2 and 7 years (bone ages 6 and 14 years, respectively). Serum testosterone levels ranged from 3.8 to 69.5 nmol/l in the four boys. Patient III had the highest testosterone levels that did not respond to hCG stimulation. The 4 year-old girl (patient V) was phenotypically normal and the acute response to GnRH was indicative of prepubertal status. Patient VI had normal menstrual cycles and fertility. CONCLUSIONS: These findings indicate variable effects of LHR activating mutations on the pituitary-gonadal axis in boys that can result in lack of normal LH and FSH release. In contrast, prepubertal and adult females were asymptomatic and had normal basal and GnRH-stimulated LH and FSH levels.     

Changes in dimeric inhibin A and B during normal early puberty in boys and girls

OBJECTIVE Although recently developed specific and sensitive assays of bioactive dimeric inhibin A and B have given new insights into the pituitary-gonadal axis in adult men and during the adult female menstrual cycle, there have been no reports on circulating inhibin A and B during normal human puberty. The aim of this study was to assess the relationship of dimeric inhibin A and B to pubertal stage, FSH and testosterone or oestradiol in late prepuberty and in early puberty. STUDY DESIGN AND SUBJECTS Serial samples were collected during a prospective longitudinal trial of GH treatment in short normal children. Seven boys were studied from late prepuberty to genital stage 3, and six pre-menarche girls from late prepuberty to breast stage 4. MEASUREMENTS Dimeric inhibin A (girls only) and inhibin B (boys and girls) were measured by highly specific and sensitive two-site ELISAs, FSH by IRMA, testosterone and oestradiol by RIA. RESULTS In boys, inhibin B increased progressively from pubertal stages 1 to 3 (ANOVA P<0.0001) and correlated strongly with mean testicular volume (r=0.72, P=0.0005). Prepubertal boys showed a positive correlation between inhibin B and FSH (r=0.65, P=0.056), whereas pubertal boys gave a strong negative correlation (r=0.75, P=0.012). In both prepubertal and pubertal boys positive correlations were observed between inhibin B (y) and testosterone (x) (r=0.81, P=0.008 and r=0.62, P=0.054 respectively), but the slope of the regression line between the two was much steeper before than after the onset of clinical puberty. In girls, both inhibin A and B increased through pubertal stages 1–4 (ANOVA P=0.01 and P=0.047 respectively). Both showed strong positive correlations with oestradiol (r=0.80 and 0.79, P=0.001) and with FSH (r=0.83, P=0.0004 and r=0.80, P=0.001). Inhibin A and B were also strongly correlated with each other (r=0.92, P=0.0001). CONCLUSIONS In boys, testicular production of inhibin B increases as puberty progresses. Our results show for the first time that the initiation of puberty is accompanied by a dramatic switch from a positive to a negative relation between inhibin B and FSH as inhibin B begins to exert the expected negative feedback on FSH. The results in girls suggest that, prior to menarche, the ovarian follicles produce inhibin A and B in strict proportion, and in progressively greater amounts as puberty proceeds. Measurement of dimeric inhibin A and B may provide a sensitive new tool for determining gonadal maturity in late prepuberty and early puberty.     

Pituitary-gonadal function in adolescent males born appropriate or small for gestational age with or without intrauterine growth restriction

CONTEXT: Being born small for gestational age (SGA) is suggested to influence female pituitary-gonadal axis, but only a few studies have focused on male pituitary-gonadal function. OBJECTIVE: Our objective was to evaluate the influence of fetal growth rate on male reproductive function. DESIGN: We conducted a follow-up study of a prospective study with data on third trimester fetal growth velocity and birth weight. SETTING: The study was conducted at Copenhagen University Hospital. PARTICIPANTS: Fifty-two healthy adolescent males participated. They were divided into those born appropriate for gestational age (AGA) and SGA, with or without intrauterine growth restriction. MAIN OUTCOME MEASURES: Pubertal stage, testicular size, and reproductive hormones were determined. Overnight 20-min LH and FSH profiles and overnight urine LH and FSH were determined in an additional study (n=30). RESULTS: No significant differences were found in testosterone levels (19.2 vs. 18.9 nmol/liter), inhibin B levels (186.5 vs. 188.0 pg/ml), or LH/testosterone ratio (0.15 vs. 0.18) between AGA and SGA, respectively. No significant differences in overnight secretory patterns of gonadotropins or testicular size and morphology were determined by ultrasonography between AGA and SGA. Fetal growth velocity did not influence any of the reproductive hormone levels. Overnight urinary LH and FSH excretion correlated statistically significantly with overnight LH (r=0.50; P=0.02) and FSH (r=0.44; P=0.04) secretion, respectively. CONCLUSION: Poor third trimester growth and/or low birth weight had no effect on subsequent male reproductive hormones. Contrasting a previous study, we found no difference in testosterone or inhibin B levels between SGA and AGA, suggesting that testicular function was not impaired in adolescent males born after compromised fetal growth.     

Hormonal changes in puberty III: Correlation of plasma dehydroepiandrosterone, testosterone, FSH, and LH with stages of puberty and bone age in normal boys and girls and in patients with Addison's disease or hypogonadism or with premature or late adrenarche.

In 104 normal boys, aged 7 to 14 years (bone ages 5 to 15 years), plasma dehydroepiandrosterone (DHEA) rose from 52.7 at 7 years, to 112.0 ng/100 ml at 10 years. A further rise occurred at 12 years (188 ng/100 ml). In relation to the bone age, DHEA increased from a mean plasma level of 31.1 at a bone age of 5 years to 77.1 ng/100 ml at one of 7 years. Further increases were observed with mean values of 163.2 at a bone age of 11 years, and of 221.2 at a bone age of 12 years, with a maximum of 333.4 ng/100 ml at bone ages of 14-15 years. The first significant increase of plasma testosterone (T) was noted at a bone age of 12 years (54.8 ng/100 ml). The major rise of T was preceded by the rise of plasma LH and was accompanied by the rise of plasma FSH. Plasma DHEA and T were also measured in 123 normal girls, ages 6 to 13 years (bone ages 5 to 15 years). DHEA rose significantly from a mean level of 44.7 at 6 years, to 80.9 ng/100 ml at 8 years, with further increases between 9 and 10 years and between 10 and 11 years. In relation to bone age, DHEA increased significantly from a mean plasma concentration of 30.9 at a bone age of 5 years, to that of 58.6 ng/100 ml at 7 years. Further increases were observed with values of 191.1 at a bone age of 10 years and 485.6 ng/100 ml at a bone age of 13 years. The first significant rise of testosterone (T) occurred at 10 years of both chronological and bone age. DHEA rose before the increase of gonadotropins. The major rise of T at a bone age of 10 years occurred concurrently with increases in plasma FSH and LH. Low levels of DHEA were observed in Addison's disease. In hypogonadotropin hypogonadism and in anorchia, DHEA levels were normal, suggesting that DHEA is produced primarily in the adrenal gland. In seven girls with early adrenarche, plasma concentrations of DHEA were in the upper range of normal values, whereas T levels were within the normal range. Conversely in girls with late adrenarche, plasms DHEA was lower than normal but T was within the normal limits. The elevation of DHEA prior to the first signs of puberty suggests that DHEA may play a role in the maturation of the hypothalamic-hypophysealgonadal axis. However, the mechanism that triggers the secretion of DHEA is not known.     

Developmentally delimited emergence of more orderly luteinizing hormone and testosterone secretion during late prepuberty in boys

To quantitate changing feedback control in the GnRH-LH/FSH-testosterone axis in male puberty, we here quantitate the orderliness of hormone release patterns using the regularity (pattern-sensitive) statistic, approximate entropy (ApEn), in 46 eugonadal boys representing 6 genitally defined stages of normal puberty. ApEn is a single variable, model-free, and scale-independent barometer of coordinate signaling or integrative regulation within a coupled neuroendocrine axis. Accordingly, we quantitated ApEn of LH profiles obtained by immunofluorometric assay of sera sampled every 20 min for 24 h. LH ApEn declined remarkably between early prepuberty (genital stage I-A: mean bone age, 4.6 +/- 1.6 yr; testis volume, <3 mL for at least 3 succeeding yr) and late prepuberty (genital stage I-C: bone age, 8.7 +/- 1.8 yr; testis volume, <3 mL for up to 1 yr thereafter; P: = 0.00019), which indicates the acquisition of more regular LH release patterns in late prepuberty. Maximal LH orderliness occurred in puberty stage II (bone age, 10.7 +/- 1.0 yr; testis volume, 2.8 +/- 0.4 mL). The LH secretory process was more disorderly in mid- and later puberty (Tanner stages III and IV). Transpubertal variations in testosterone ApEn manifested a similar tempo, i.e. the greatest regularity of testosterone secretion (lowest ApEn) emerged in Tanner genital stage II (P: < 10(-)(7)), with less orderly patterns evident both earlier and later in sexual development. In contrast, FSH ApEn values remained invariant of pubertal status. Analysis of bihormonal coupling using the theoretically related bivariate cross-ApEn statistic disclosed maximal 2-hormone synchrony for LH and testosterone secretion in genital stage II (P: = 0.031), with relative deterioration of coordinate LH and testosterone release patterns both before and after. LH and FSH release became maximally synchronous at the end of prepuberty (genital stage I-C; P: = 0.029), and FSH and testosterone synchrony peaked in pubertal stage III (P: = 0.037). As mean 24-h serum concentrations of LH, FSH, and testosterone rose transpubertally by 35-fold (LH), 68-fold (FSH), and 70-fold (testosterone), respectively, we infer that pubertal developmental stage per se rather than level of hormone output dictates coordinate GnRH-LH/FSH-testosterone secretion. In summary, in eugonadal boys, the regularity of 24-h LH and testosterone secretory patterns undergoes well defined pubertal stage-specific control. No sexually developmentally delimited regulation is inferable for FSH. The concept of temporally biphasic puberty-dependent variations in neurohormone secretory regularity contrasts with the unidirectional rise in daily hormone output. Accordingly, we infer that late prepuberty and early puberty (Tanner genital stages IC and II) embody a physiologically unique sexual developmental window, marked by transiently enhanced LH and testosterone feedback stability in boys. Whether analogous plasticity of hypothalamo-pituitary-gonadal interactions unfolds during female adolescence is not known.     

Time course of the serum gonadotropin surge, inhibins, and anti-Müllerian hormone in normal newborn males during the first month of life

CONTEXT: Newborns with ambiguous genitalia or males with nonpalpable gonads usually require an early assessment of the presence and functional state of testicular tissue. OBJECTIVE: Our objective was to characterize the precise ontogeny of the serum patterns of gonadotropins, testosterone, anti-Müllerian hormone (AMH), and inhibins in normal newborn boys. DESIGN: We conducted a cross-sectional and longitudinal study. SUBJECTS: Serum samples were obtained in 57 boys and 13 girls on d 2 of life. A second sample was obtained on d 7, 10, 15, 20, and 30 (boys) and on d 30 (girls). MAIN OUTCOME MEASURES: Serum levels of gonadotropins, testosterone, AMH, and inhibins were measured. RESULTS: In males, LH and FSH were undetectable or very low on d 2. By d 7, LH increased to 3.94 +/- 3.19 IU/liter (mean +/- sd) and FSH to 2.04 +/- 1.67 IU/liter. LH/FSH ratios were 0.40 +/- 0.11 (d 2) and 2.02 +/- 0.20 (d 30). AMH rose from 371 +/- 168 pmol/liter (d 2) to 699 +/- 245 pmol/liter (d 30), and inhibin B rose from 214 +/- 86 ng/liter (d 2) to 361 +/- 93 ng/liter (d 30). The inhibin alpha-subunit precursor (pro-alphaC) remained stable during the first month of life. Testosterone levels were 66 +/- 42 ng/dl (d 2), 82 +/- 24 ng/dl (d 20), and 210 +/- 130 ng/dl (d 30). A sexual dimorphism was observed in AMH and inhibin B (lower in girls on d 2 and 30), in LH/FSH ratio (lower in girls on d 30) and in testosterone (lower in girls on d 30). CONCLUSIONS: Sertoli cell markers AMH and inhibin B are the earliest useful markers indicating the existence of normal testicular tissue.     

Testicular anti-mullerian hormone secretion is stimulated by recombinant human FSH in patients with congenital hypogonadotropic hypogonadism

Serum anti-Mullerian hormone (AMH), a prepubertal Sertoli cell marker, declines during puberty as an early sign of testicular testosterone (T) production. When T synthesis or action is impaired, serum AMH is abnormally high in the first months after birth and at puberty but normal between these two periods. We postulated that FSH might be responsible for AMH up-regulation in the absence of androgen inhibition. To test this hypothesis, we administered recombinant human (rh) FSH to eight patients aged from 18-31 yr with untreated congenital hypogonadotropic hypogonadism. This situation is ideal to study the effect of FSH on AMH production because it avoids interference by endogenous gonadotropins and T. The patients received daily sc injections of 150 IU rhFSH for 1 month, followed in seven of them by a combined treatment of rhFSH plus human chorionic gonadotropin (hCG; 1500 UI im, twice a week) for 2 months. Gonadotropins, T, AMH, and inhibin B were measured in plasma before treatment every 10 d during rhFSH treatment and every month during combined rhFSH and hCG treatments. All hormones were at prepubertal levels before treatment. Although LH and T did not vary, AMH and inhibin B levels gradually increased after 20 d of FSH administration. However, in contrast to rhFSH alone, the combined rhFSH plus hCG stimulation of the testis dramatically suppresses the secretion of AMH and induced a modest but significant reduction of circulating inhibin B levels. We conclude that FSH stimulates AMH production in the testis when it is at a prepubertal stage. In addition, the decrease of serum AMH during combined rhFSH and hCG testicular stimulation is in agreement with the concept that during pubertal development and in adult life, the suppressive effect of LH-driven testicular androgens outweighs the stimulating effect of FSH on AMH production by Sertoli cells. Finally, the hCG-induced decrease in inhibin B suggests that in humans, as previously demonstrated in monkeys, testicular T is also able to inhibit inhibin B secretion.     

Establishment of testicular endocrine function impairment during childhood and puberty in boys with Klinefelter syndrome

Objective To precisely characterize the chronology of testicular endocrine function impairment during childhood and adolescence in patients with Klinefelter syndrome. Design Retrospective chart review. Patients A total of 29 boys with Klinefelter syndrome with up to 12·3 years follow‐up. Measurements Clinical features and serum hormone levels were analysed during follow‐up. Results Of the 29 patients, 16 were prepubertal and 13 had already entered puberty at their first visit. Fifteen patients were followed up through late puberty. Before puberty, LH, FSH, testosterone, anti‐Müllerian hormone (AMH) and inhibin B were within the expected range in almost all cases. However, levels of the inhibin α‐subunit precursor Pro‐αC were in the lowest levels of the normal range in most cases. During puberty, FSH levels increased earlier and more markedly than LH. Inhibin B and AMH declined to abnormally low or undetectable levels in advanced pubertal stages. Although testosterone and Pro‐αC levels were within the reference ranges in most cases, they were abnormally low for the observed LH values. Conclusions In Klinefelter syndrome, a mild Leydig cell dysfunction is present from early childhood in most cases and persists throughout puberty. Sertoli cell function is normal until mid puberty, when a dramatic impairment is observed.     

TESTICULAR FUNCTION FOLLOWING IRRADIATION OF THE HUMAN PREPUBERTAL TESTIS

Testicular function was studied in ten men, aged between 17 and 36 years, who had received irradiation for a nephroblastoma during childhood. The dose of scattered irradiation to the testes ranged from 268 to 983 rad. Eight subjects had either oligo- or azoospermia (0 to 5.6 million/ml), seven of whom had an elevated serum follicle-stimulating hormone (FSH) level. One subject showed evidence of Leydig cell dysfunction with a raised serum luteinizing hormone level (LH) and a low plasma testosterone concentration. A second group of eight prepubertal males, aged between 8 and 14 years, were studied. These had also been irradiated for abdominal malignancies during childhood and received a similar dose of irradiation to the testis as the first group studied. The plasma testosterone levels were within the normal range for prepubertal boys in all eight. The mean gonadotrophin levels were not significantly different from the mean levels of normal prepubertal males. Thus irradiation-induced damage to the germinal epithelium in prepubertal boys produces raised FSH levels after puberty but not before it. We conclude, therefore, that inhibition has a minor role in the control of the prepubertal hypothalamic-pituitary testicular axis and its contribution to gonadal control of gonadotrophin secretion changes with sexual maturation.