A new test of combined pituitary-testicular function using the gonadotropin-releasing hormone agonist nafarelin in the differentiation of gonadotropin deficiency from delayed puberty: pilot studies

Pubertal delay: the challenge of a timely differential diagnosis between congenital hypogonadotropic hypogonadism and constitutional delay of growth and puberty

Distinguishing between constitutional delay of growth and puberty (CDGP) and congenital hypogonadotropic hypogonadism (CHH) may be challenging. CDGP and CHH appear to belong to the same clinical spectrum (with low sex hormones and low LH and FSH), although one is classically transient and known as a self-limited form of delayed puberty (CDGP) while the other is permanent (CHH). Thus, the clinical history and the outcomes of these two conditions require different approaches, and an adequate and timely management for the patients is mandatory. Since the initial presentation of CDGP and CHH is almost identical and given the similarities of CDGP and partial forms of CHH (i.e. patients with partial and early interrupted pubertal development) the scientific community has been struggling to find some diagnostic tests able to allow an accurate differential diagnosis between these two conditions in delayed puberty. In this review we provide an up to date insight on the tests available, their meanings and accuracy, as well as some clues to effectively differentiate between constitutional pubertal delay and pathologic CHH.

Dynamic Testing for Evaluation of Adrenal and Gonadal Function in Pediatric and Adult Endocrinology: An Overview

Dynamic tests are often considered as the backbone of endocrinology. These tests involve the use of an exogenous agent to manipulate the body's hormonal milieu for the diagnosis and characterization of an endocrine disorder. They are especially helpful in the evaluation of certain endocrine conditions, such as disorders of growth and pubertal maturation and disorders of sex development. A great deal of heterogeneity exists across clinicians with regard to the usage, methodology, and interpretation of these tests. This review outlines various dynamic tests used to evaluate adrenal and gonadal function in pediatric and adult endocrinology, along with their clinical application and interpretation.

Baseline inhibin B and anti-Mullerian hormone measurements for diagnosis of hypogonadotropic hypogonadism (HH) in boys with delayed puberty

CONTEXT

The diagnosis of isolated hypogonadotropic hypogonadism (IHH) in boys with delayed puberty is challenging, as may be the diagnosis of hypogonadotropic hypogonadism (HH) in boys with combined pituitary hormone deficiency (CPHD). Yet, the therapeutic choices for puberty induction depend on accurate diagnosis and may influence future fertility.

OBJECTIVE

The aim was to assess the utility of baseline inhibin B (INHB) and anti-Mullerian hormone (AMH) measurements to discriminate HH from constitutional delay of puberty (CDP). Both hormones are produced by Sertoli cells upon FSH stimulation. Moreover, prepubertal AMH levels are high as a reflection of Sertoli cell integrity.

PATIENTS

We studied 82 boys aged 14 to 18 yr with pubertal delay: 16 had IHH, 15 congenital HH within CPHD, and 51 CDP, as confirmed by follow-up. Subjects were genital stage 1 (testis volume<3 ml; 9 IHH, 7 CPHD, and 23 CDP) or early stage 2 (testis volume, 3-6 ml; 7 IHH, 8 CPHD, and 28 CDP).

RESULTS

Age and testis volume were similar in the three groups. Compared with CDP subjects, IHH and CPHD subjects had lower INHB, testosterone, FSH, and LH concentrations (P<0.05), whereas AMH concentration was lower only in IHH and CPHD subjects with genital stage 1, likely reflecting a smaller pool of Sertoli cells in profound HH. In IHH and CPHD boys with genital stage 1, sensitivity and specificity were 100% for INHB concentration of 35 pg/ml or less. In IHH and CPHD boys with genital stage 2, sensitivities were 86 and 80%, whereas specificities were 92% and 88%, respectively, for an INHB concentration of 65 pg/ml or less. The performance of testosterone, AMH, FSH, and LH measurements was lower. No combination or ratio of hormones performed better than INHB alone.

CONCLUSION

Discrimination of HH from CDP with baseline INHB measurement was excellent in subjects with genital stage 1 and fair in subjects with genital stage 2.

Potential diagnostic utility of intermittent administration of short-acting gonadotropin-releasing hormone agonist in gonadotropin deficiency

OBJECTIVE

To determine if intermittent, low-dose, short-acting gonadotropin-releasing hormone agonist (GnRH-agonist) administration sufficiently up-regulates pituitary-gonadal function in gonadotropin deficiency to be of diagnostic or therapeutic value.

DESIGN

Case-control study.

SETTING

General clinical research center.

PATIENT(S)

Normal adult volunteers and gonadotropin-deficiency patients.

INTERVENTION(S)

Low-dose leuprolide acetate administered subcutaneously at 4- to 5-day intervals up to 1 year.

MAIN OUTCOME MEASURE(S)

Levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), and sex steroid responses.

RESULT(S)

In normal men and women, low-dose GnRH-agonist repetitively transiently stimulated gonadotropins in a gender-dimorphic manner. In congenitally gonadotropin-deficient men (n = 6) and women (n = 1), none of whom had a normal LH response to an initial GnRH-agonist test dose, this regimen consistently stimulated LH to the normal baseline range within 2 weeks. Long-term GnRH-agonist administration to a partially gonadotropin-deficient man did not alleviate hypogonadism, however. Women with hypothalamic amenorrhea (n = 2) responded normally to a single GnRH-agonist injection; however, repeated dosing did not seem to induce the normal priming effect.

CONCLUSION(S)

The subnormal LH response to GnRH-agonist in patients with congenital gonadotropin deficiency normalized in response to repetitive intermittent GnRH-agonist administration but not sufficiently to improve hypogonadism. Hypothalamic amenorrhea patients lacked the priming response to repeated GnRH-agonist but otherwise had normal hormonal responses to GnRH-agonist. We conclude that intermittent administration of a short-acting GnRH-agonist is of potential diagnostic value in distinguishing hypothalamic from pituitary causes of gonadotropin deficiency.

Leuprolide acetate gonadotrophin response patterns during female puberty

OBJECTIVE

To assess normative data and the usefulness of spontaneous and LHRH analogue-stimulated serum LH and FSH levels measured by immunoradiometric assays (IRMA) in the evaluation of normal puberty.

DESIGN

Prospective. Healthy girls in Tanner I and Tanner II from the local community were invited to participate (n = 47).

METHODS

A leuprolide acetate test (500 mcg/m(2); sc) was performed. LH and FSH levels were determined using IRMA. Tanner II girls were assessed every 6 months until Tanner V. Girls who progressed from Tanner II to Tanner III in the next 6 months were called Tanner II-2; otherwise, they were called Tanner II-1.

RESULTS

The prepubertal upper limit (CI 95%) was 0.49 IU/l for basal LH and 5.1 IU/l for stimulated LH. Taking into account these LH cut-off limits, 72.2% and 66.7% of Tanner II-1 and 41.6% and 41.7% of Tanner II-2 subjects presented overlapping values for basal and stimulated LH, respectively, as compared with the Tanner I group. The cut-offs for basal and stimulated LH to predict progression from Tanner II to Tanner III in the next 6 months were a basal LH level > or =0.49 IU/l (Sensitivity = 0.58; 1-Specificity = 0.33) and a poststimulated LH level > or =4.75 IU/l (Sensitivity = 0.67; 1-Specificity = 0.44).

CONCLUSION

According to an IRMA, the basal and leuprolide acetate gonadotrophin response patterns during the beginning stages of puberty overlapped between Tanner I and Tanner II, and the cut-offs of basal and stimulated LH levels to predict progress from Tanner II to Tanner III had low sensitivities for the following 6 months.

Role of gonadotropin-releasing hormone and human chorionic gonadotropin stimulation tests in differentiating patients with hypogonadotropic hypogonadism from those with constitutional delay of growth and puberty

BACKGROUND

Delayed puberty can be due to either constitutional delay of growth and puberty (CDGP) or hypogonadotropic hypogonadism (HH). Differentiating between the two using current testing can be difficult. We assessed the utility of a GnRH test in combination with a 3-d and 19-d human chorionic gonadotropin (HCG) test to discriminate between the two conditions.

METHODS

We performed a retrospective analysis of 43 boys with pubertal delay who required pubertal induction with testosterone. All were followed through puberty; 29 were subsequently diagnosed with CDGP and 14 with HH. A standard GnRH test (2.5 microg/kg) was undertaken and was followed by a short [3 d; n = 38 (13 HH, 25 CDGP)] or extended [19 d; n = 31 (12 HH, 19 CDGP)] HCG stimulation test, or both [n = 27 (11 HH, 16 CDGP)]. Receiver operating characteristic analysis was performed to assess the performance of the tests.

RESULTS

Peak testosterone concentrations to both 3-d and 19-d HCG tests were significantly lower in patients with HH compared with CDGP. The 19-d test performed better than the 3-d test, and a combination of the LHRH, 3-d and 19 d HCG test [peak LH cutoff, 2.8 U/liter; peak 3-d testosterone cutoff, 1.04 microg/liter (3.6 nmol/liter); peak 19-d testosterone cutoff, 2.75 microg/liter (9.5 nmol/liter)] gave a sensitivity and a specificity of 100%.

CONCLUSIONS

Our data suggest that a GnRH test in combination with both a 3-d and 19-d HCG test may aid in differentiating between CDGP and HH.

Male hypogonadism

The hypothalamic-pituitary-gonadal (HPG) axis regulates the development, endocrine and reproductive function of the gonads throughout all phases of life. Male hypogonadism is defined an inadequate gonadal function, as manifested by deficiency in gametogenesis and/or secretion of gonadal hormones. In most cases, male hypogonadism is diagnosed through detailed history, physical examination and a few basic hormonal evaluations. In selected cases, however, additional tests are needed to define the aetiology and the extent of HPG axis dysfunction. These include semen analysis, pituitary imaging studies, genetic studies, bone densitometry, testicular ultrasonography, testicular biopsy and hormonal dynamic testing. The stimulation tests of the HPG are of particular importance in the differential diagnosis of congenital delayed puberty versus pre-pubertal hypogonadism in children. This review will focus on the methods, indications and limitations of endocrine testing in the characterisation and differential diagnosis of male hypogonadism at various ages. A practical hands-on guide on how to perform these tests is also provided.

Constitutional delayed puberty in males and hypogonadotropic hypogonadism: a reliable and cost-effective approach to differential diagnosis

Forty-six male teenagers 13-19 years old with delayed puberty (DP) underwent gonadotropin releasing hormone (GnRH) and human chorionic gonadotropin (HCG) stimulation as part of their work-up. All were followed to age 18 and beyond. Thirty-seven had constitutional delayed puberty (CDP). Nine had hypogonadotropic hypogonadism (HH). At referral 34 youngsters with CDP were properly diagnosed when the lower limit for the luteinizing hormone (LH) response to GnRH (Factrel 0.1 mg i.v.) was set at 12 IU/l. Three boys with CDP failed to reach that level and were not assigned appropriately. All nine patients with HH had basal serum testosterone (T) < 50 ng/dl when first seen and LH responses to GnRH stimulation < 8.0 IU/l. In the late 1970s, five subjects with DP were given HCG 3,000 IU (two patients daily for 5 days; three on 3 alternate days). Serum T was measured before the first, and 48 hours after the last injection (day 7). With recognition of the long biological half-life of injected HCG and receptor downregulation by daily doses, the protocol was changed. In the early 1980s, the dose of HCG was randomized to either 500 IU or 1,000 IU given on 3 alternate days. T was measured before the first injection (basal), 48 hours later (day 3) and 48 hours after the third injection (day 7). At referral 35 patients with CDP, including one GnRH failure, met the criterion for a positive response to HCG stimulation based on their own reactions (T > 170 ng/dl on day 3; > 200 on day 7). Eleven patients with DP failed the test. Nine had HH and two had CDP. The nine patients with HH included the two given daily injections and the three given HCG 3,000 IU on 3 alternate days. Of the two with CDP, one, an obese boy with a normal GnRH test, only received 500 IU HCG (5.6 IU/kg), which may have been inadequate. The other failed both tests. Of the 35 responders, 17 (group 1) were given HCG 500 IU and 18 (group 2) were given 1,000 IU i.m. on 3 alternate days. Seven boys in group 1 and 12 in group 2 had serum T determined on day 3, and all 35 had T measured on day 7. There was no significant difference between the basal T levels in the two groups or in their responses to HCG, and the results were pooled. The combined data in the patients with CDP were then compared with those of the nine patients with HH, recognizing that the result on day 7 in the two patients given daily injections may reflect receptor down-regulation. Setting the limit for a normal T response at > 170 ng/dl 48 hours after a single injection of HCG and > 200 ng/dl after the third injection assigned all the patients with CDP appropriately. The data on the patients with HH are less complete, with only three T values 48 hours after the first injection However, even after three injections of HCG on alternate days, only one of nine patients with HH approached the lowest level achieved by the patients with CDP after a single injection. The data confirm that a basal serum T 50 ng/dl is evidence of the onset of puberty. In those with serum T < 50 ng/ dl our data suggest that a single injection of HCG 15 IU/kg, with serum T determined 48 hours later, is more discriminatory and offers the most reliable, easy to perform, least painful, and by far the most cost effective test to differentiate CDP from HH.

Diagnostic utility of a low-dose gonadotropin-releasing hormone test in the context of puberty disorders

OBJECTIVES

The 10-microg gonadotropin-releasing hormone (GnRH) test assesses pituitary gonadotroph responsiveness, whereas the 100-microg dose assesses maximal secretory capacity. Our aims were to establish normative data for the low-dose test in children and to evaluate the test in diagnosing common pubertal disorders.

METHODS

We retrospectively classified 107 children who underwent 10-microg GnRH tests into normal prepubertal (20 boys, 10 girls), normal early pubertal (10 boys, 16 girls), constitutional delay of puberty (CDP, 13 prepubertal boys >12 years), hypogonadotropic hypogonadism (HH, 5 prepubertal boys >12 years), central precocious puberty (CPP, 19 girls) or premature thelarche/variant (13 girls).

RESULTS

Peak LH response was higher in prepubertal boys >12 years compared with younger boys (p < 0.01) but showed no further change in early puberty. CDP boys had LH responses similar to prepubertal boys >12 years. HH boys showed an absent LH response which diagnosed HH with 100% sensitivity and 96% specificity. Thelarche girls had LH:FSH peak ratios lower than normal prepubertal (p = 0.001), pubertal (p < 0.05) or CPP (p = 0.001) girls.

CONCLUSIONS

We have established normative values for the low-dose GnRH test in children. The test successfully differentiated HH from CDP in boys, and contributed to the differential diagnosis of CPP and premature thelarche in girls.

Usefulness of the free alpha-subunit to diagnose hypogonadotropic hypogonadism

OBJECTIVE

Differentiating constitutional delay of growth and puberty from hypogonadotropic hypogonadism is still a problem in clinical practice. Our previous study demonstrated that the peak/basal ratio of the free alpha-subunit of the glycoprotein hormones is higher in normal prepubertal boys than in male adults with hypogonadotropic hypogonadism. The objective of this study was to assess the performance of this ratio in normal male patients at different ages and levels of pubertal development, and in patients with hypogonadotropic hypogonadism, both isolated and combined with other pituitary hormone deficiencies.

DESIGN

Cohort study.

PATIENTS

Twenty-eight normal prepubertal males between 6 and 8 years; 20 normal prepubertal males between 9 and 13 years; 18 males with constitutional delay of growth and puberty; 26 normal pubertal males; 13 adult men with isolated hypogonadotropic hypogonadism; 21 adult men with complete hypogonadotropic hypogonadism combined with other hormone deficiencies; and 11 adult men with partial hypogonadotropic hypogonadism combined with other hormone deficiencies.

MEASUREMENTS

Serum levels of free alpha-subunit immediately before (basal), and 30 and 60 min after 100 micro g intravenous GnRH were measured by immunofluorimetry. Median and P25-P75 range of the peak/basal ratio of the free alpha-subunit was determined for each group. A receiver operating characteristics curve was calculated. Results were compared using the Kruskal-Wallis test.

RESULTS

The peak/basal ratio of the free alpha-subunit was higher in patients with constitutional delay of growth and puberty (7.46) than in those with isolated hypogonadotropic hypogonadism (2.73), complete combined hypogonadotropic hypogonadism (1.58), and partial combined hypogonadotropic hypogonadism (2.61; P < 0.001). A peak/basal ratio < 3.26 identified hypogonadotropic hypogonadism with 93.2% sensitivity and 94.4% specificity when compared to constitutional delay of growth and puberty. There was no statistical difference between the peak/basal ratio of prepubertal patients between 6 and 8 years (7.20), patients between 8 and 13 years (8.71), normal pubertal males (8.10) and those with constitutional delay of growth and puberty (7.46). In a group of boys with delayed puberty, a cut-off point of 3.69 defined hypogonadotropic hypogonadism with 95.6% sensitivity and 94.4% specificity. A cut-off point of 4.81 gave 100% sensitivity (88.9% specificity), and 3.09 gave 100% specificity (86.7% sensitivity).

CONCLUSIONS

The peak/basal ratio of the free alpha-subunit can be used for the differential diagnosis of constitutional delay of growth and puberty and hypogonadotropic hypogonadism, irrespective of age. This distinction allows early investigation and treatment of patients with hypogonadotropic hypogonadism and reassurance for those with constitutional delay of growth and puberty.

Use of GnRH agonist and human chorionic gonadotrophin tests for differentiating constitutional delayed puberty from gonadotrophin deficiency in boys

OBJECTIVES

The differentiation of constitutional delayed puberty (CDP) from gonadotrophin deficiency (GD) in boys at referral poses a difficult challenge. The effectiveness of the GnRH agonist (GnRH-a) test in distinguishing between the two conditions was evaluated and compared with findings of the GnRH and hCG stimulation tests. PATIENTS, METHODS AND DESIGN: The study sample included 32 prepubertal boys aged 14 years or older. Thirteen entered spontaneous puberty within 1 year of referral (group A) and 19 remained prepubertal (group B). All underwent the GnRH test (Relefact, Hoechst AG, 0.1 mg/m2 i.v. in one bolus), GnRH-a test (Decapeptyl, Ferring GmbH, 0.1 mg/m2 s.c.) and hCG stimulation (Chorigon, Teva, 1500 units i.m. on three alternate days) at 1-week intervals. All tests were performed at referral at 0800 h. Blood samples were collected before testing and at 30 and 60 min (GnRH test) or 4 h (GnRH-a) for LH and FSH determination, and before testing and at 4 h (GnRH-a) or on the seventh day (hCG) after stimulation for serum testosterone measurement.

RESULTS

The LH response to GnRH-a and the testosterone response to hCG stimulation were significantly higher in group A (LH, mean +/- SD 20.4 +/- 7.5 mIU/ml, range 10.8-32.6; testosterone, mean +/- SD 18.0 +/- 5.9 nmol/l, range 9.4-26, P < 0.0001) than in group B (LH, mean +/- SD 2.3 +/- 2.0 mIU/ml, range 0.7-6.9; testosterone, mean +/- SD 1.0 +/- 0.7 nmol/l, range 0.7-3.2), with no overlap between the groups. The cut-off for the LH response to GnRH-a was 8.0 mIU/ml, and for the testosterone response to hCG, 8 nmol/l. There were also significant differences between the groups in mean basal serum LH and FSH (LH, 1.1 +/- 0.5 vs. 0.6 +/- 0.2 mIU/ml, P < 0.05; FSH, 2.2 +/- 2.0 vs. 0.4 +/- 0.3 mIU/ml, P < 0.02) and their response to GnRH (LH, 11.4 +/- 4.4 vs. 2.7 +/- 1.1 mIU/ml, P < 0.0001; FSH, 5.1 +/- 3.4 vs. 2.5 +/- 2.4 mIU/ml, P < 0.0001), and mean serum testosterone level at 4 h after GnRH-a administration (1.9 +/- 1.0 vs. 0.9 +/- 0.4 nmol/l, P = 0.002), but all showed a great overlap in range. Mean age, testicular volume and basal serum testosterone levels were similar in the two groups at referral. One year later, the testicular volume of group A (5.0-12.0 ml) was significantly larger than that of group B (1.0-3.0 ml, P < 0.0001), which remained unchanged on re-examination 3.0 +/- 0.5 years later.

CONCLUSIONS

The GnRH-agonist test and the repeated-injection hCG test are reliable diagnostic tools for differentiating CDP from GD in boys.

Leuteinizing hormone responses to leuprolide acetate discriminate between hypogonadotropic hypogonadism and constitutional delay of puberty

OBJECTIVE

To assess if leuprolide acetate stimulation discriminates between hypogonadotropic hypogonadism (HH) and constitutional delay of puberty (CDP) in males.

DESIGN

Case-control study.

SETTING

Patients attending an academic research environment.

PATIENTS

Only male patients were studied: 10 with HH (group 1, age 16.5 +/- 6.0 years), 8 prepubertal with CDP (group 2, age 14.3 +/- 1.2 years), 6 healthy prepubertal (group 3, age 9.5 +/- 3.3 years), and 8 healthy late-pubertal (group 4, age 15.1 +/- 3.1 years).

INTERVENTION(S)

Blood samples were obtained after an overnight fast. Leuprolide acetate was then administered SC, and blood samples were drawn at 0, 30, 60, 120, 180 minutes, and 6 and 24 hours after stimulation.

MAIN OUTCOME MEASURE(S)

Clinical follow-up evaluations of data and serum levels of LH, FSH, 17-hydroxyprogesterone, and testosterone.

RESULT(S)

Basal LH levels were similar in groups 1 through 3 and differed significantly from those in group 4. Peak serum LH levels were significantly higher in CDP compared with HH (8.9 +/- 1.4 vs. 1.4 +/- 0.2 IU/L). Baseline FSH levels were significantly higher only in pubertal boys (versus the HH group); peak levels did not differ among the groups. Basal and peak testosterone levels were significantly higher only in the control pubertal group when compared to the other groups; peak 17-hydroxyprogesterone concentrations were significantly higher in pubertal controls compared with HH and CDP.

CONCLUSION(S)

Peak LH responses clearly discriminate HH from CDP. Timing for blood sampling should be fixed at 0, 60, 120, 180 minutes after stimulation.

Premature adrenarche--normal variant or forerunner of adult disease?

Adrenarche is the puberty of the adrenal gland. The descriptive term pubarche indicates the appearance of pubic hair, which may be accompanied by axillary hair. This process is considered premature if it occurs before age 8 yr in girls and 9 yr in boys. The chief hormonal product of adrenarche is dehydroepiandrosterone (DHEA) and its sulfated product DHEA-S. The well documented evolution of adrenarche in primates and man is incompatible with either a neutral or harmful role for DHEA and implies most likely a positive role for some aspect of young adult pubertal maturation and developmental maturation. Premature adrenarche has no adverse effects on the onset and progression of gonadarche in final height. Both extra- and intraadrenal factors regulate adrenal androgen secretion. Recent studies have shown that premature adrenarche in childhood may have consequences such as functional ovarian hyperandrogenism, polycystic ovarian syndrome, and insulin resistance in later life, sometimes already recognizable in childhood or adolescence. Premature adrenarche may thus be a forerunner of syndrome X in some children. The association of these endocrine-metabolic abnormalities with reduced fetal growth and their genetic basis remain to be elucidated.

Serum prostate specific antigen, sex hormone binding globulin and free androgen index as markers of pubertal development in boys

OBJECTIVE

Prostate specific antigen (PSA) expression in the prostate gland is regulated by androgens. Serum levels of PSA are undetectable by routine assays in normal boys. Measurable values could serve as a marker for pubertal development. In order to explore this question, we measured serum PSA levels in normal boys throughout puberty and examined the interrelationships with various hormonal and physical developmental changes.

DESIGN

Sera from 77 normal boys in Tanner stages I to V (T-I to T-V) were analysed for PSA levels by a sensitive time-resolved fluoro-immunometric assay (sensitivity: 0.012 microgram/l). In addition, sex hormone binding globulin (SHBG), insulin like growth factor I (IGF-I), IGF binding protein 3(IGFBP-3) and testosterone were measured.

RESULTS

PSA was detectable in 0% of Stage T-I (n = 16), 33% of T-II (n = 18), 65% of T-III (n = 17) and 100% of T-IV (n = 10) and T-V (n = 16) boys. PSA levels rose significantly according to stage (P < 0.05). Also, there were significant (P < 0.05) increments in serum testosterone, IGF-I and IGFBP-3 levels from stages T-I to T-IV. PSA showed a positive correlation with testosterone (r = 0.86, P < 0.001), IGF-I (r = 0.66, P < 0.001), and IGFBP-3 (r = 0.34, P = 0.004) levels. Both PSA and these analytes, however, showed significant overlap between stages T-I and T-II with only 6/18 (33%) and 12/18 (66%) of T-II subjects having PSA and testosterone levels, respectively, above the T-I range. In contrast, serum SHBG levels decreased markedly from stages I to II (P < 0.001). At the calculated best cut-off point for SHBG of 50 nmol/l, 16/18 T-II subjects had values below the T-I range (sensitivity = 89%). Because of this decrement of SHBG and the increasing testosterone secretion in early puberty, the Free Androgen Index (FAI = Testosterone/SHBG) could even better differentiate the onset of puberty with all except one of the T-II subjects having FAI levels above the T-I range (sensitivity = 94.4%). The decrease of SHBG in T-II subjects coincided with an increase in total body weight (P = 0.001) and body mass index (BMI, P = 0.0003). Despite the continuing pubertal rise in testosterone, SHBG levels showed a rebound increment from T-II-T-III subjects (P = 0.02) with a concomitant decrease in BMI (P = 0.0014).

CONCLUSIONS

Prostate specific antigen closely reflects serum free androgen activity during puberty. However, it was unable to differentiate the earliest pubertal development. In comparison, SHBG levels and Free Androgen Index are more sensitive markers for the onset of puberty in boys. The inverse association between SHBG levels and BMI in pubertal stages Tanner stages, I to III suggests that body fatness, via its effect on insulin sensitivity, may play an important role in the regulation of SHBG production during early pubertal development.

Delayed puberty in obese boys: comparison with constitutional delayed puberty and response to testosterone therapy

OBJECTIVE

To evaluate the results of a brief course of testosterone therapy in boys with delayed puberty and to compare the responses seen in boys with constitutional delayed puberty (CDP), boys with obesity, and boys with possible gonadotropin deficiency.

DESIGN AND SETTING

A retrospective chart review was done for 36 boys aged 14 years or older, seen between 1983 and 1996 because of delayed puberty, who were given 4 monthly injections of testosterone, 100 mg/mo, and had adequate follow-up.

RESULTS

There were 23 boys whose findings before and after treatment were consistent with a diagnosis of CDP. Testosterone treatment increased the growth rate from 4.3 cm/y to 11.2 cm/y (P <.00001), and mean testis length increased 0.6 to 0.8 cm in all (from a mean of 2.9 to 3.6 cm, P <.00001) in the 4 months after testosterone treatment. Serum testosterone 4 months after therapy was higher than that before therapy (P =.00003). Of 5 boys with growth hormone deficiency but unknown gonadotropin status, 2 had lack of progression after testosterone therapy and were believed to have permanent gonadotropin deficiency. Seven of the 36 boys were obese (body mass index, >25), and 6 had a response to testosterone similar to boys with CDP with clear pubertal progression. One obese boy and one nonobese boy were diagnosed as having isolated gonadotropin deficiency.

CONCLUSIONS

Monitoring the growth and genital responses to a 4-month course of testosterone injections helps to differentiate CDP from gonadotropin deficiency in boys with delayed puberty. Obese boys constitute a distinct category of boys with pubertal delay in terms of their growth, but their response to testosterone is similar to that observed in boys with classic CDP.

Central Hypogonadism: Distinguishing Idiopathic Low Testosterone from Pituitary Tumors

OBJECTIVE

To attempt to determine clinical or hormonal characteristics that could help distinguish benign idiopathic low testosterone (ILT) from pituitary tumor.

METHODS

On retrospective review of medical records of patients encountered by Johns Hopkins endocrine staff between 1985 and July 1995, 64 patients who fulfilled our enrollment criteria--27 men with ILT and 37 patients with imaging-proven pituitary tumor--were identified. Men 21 years of age or older needed to have had serum testosterone, luteinizing hormone (LH), follicle-stimulating hormone (FSH), and prolactin levels measured before hormonal replacement therapy or pituitary tumor extirpation (or both) and a high-quality imaging scan (computed tomography or magnetic resonance imaging) done and interpreted by the Johns Hopkins radiology staff.

RESULTS

In comparison with men who had ILT, men with pituitary tumors had similar serum testosterone levels and significantly higher serum levels of LH, FSH, and prolactin. In addition, significantly more men with pituitary tumors had visual field abnormalities, headaches, and symptoms of hypothyroidism in comparison with the men with ILT. In contrast, the group with ILT complained significantly more of impotence, erectile dysfunction, and depression than did the group with pituitary tumors. The age at initial assessment was comparable in both study groups.

CONCLUSION

Although age at initial manifestation did not predict the presence of pituitary tumor, the group of men with tumors were more likely than those with ILT to have serum testosterone levels <150 ng/dL, higher serum gonadotropin and prolactin levels, and visual field abnormalities and less likely to have sexual dysfunction. Therefore, on the basis of our data, we recommend that men with these findings should be referred for a magnetic resonance image to exclude the presence of a tumor.

New aspects in the diagnosis and treatment of pubertal disorders

Recent developments in biochemistry, genetics, and clinical research have produced a profound effect on the understanding of normal and abnormal puberty. This article is intended to point out selected new developments that affect the understanding of puberty and clinical practice in disorders of puberty.

Gonadal function and response to growth hormone (GH) in boys with isolated GH deficiency and to GH and gonadotropins in boys with multiple pituitary hormone deficiencies

OBJECTIVE

[corrected] To evaluate spermatogenesis in patients with isolated GH deficiency and multiple pituitary hormone deficiencies.

DESIGN

Treatment of isolated GH-deficient patients with recombinant human GH (weekly dose of 0.7 IU/kg) for 5.3 +/- 0.4 (mean +/- SD) years and cotreatment of multiple pituitary deficient patients with GH at the same dosage for 8.0 +/- 0.4 years and hCG (2,000 IU, three times per week) and hMG (500 IU, two times per week) for 13.7 +/- 1.1 months.

SETTING

Endocrine Pediatric Unit.

PATIENTS

Eight patients affected by isolated GH deficiency and seven by multiple pituitary hormone deficiencies.

MAIN OUTCOME MEASURES

Serum LH, FSH, and T, testicular volume, semen volume, density, count, and motility.

RESULTS

Patients with isolated GH deficiency completed their pubertal development in 19.0 +/- 3.5 months and patients with multiple pituitary hormone deficiencies in 13.7 +/- 1.1 months. At the end of puberty, the two groups of patients had similar testicular volume, penis size, sperm concentration, motility, and morphology, although T levels and seminal volume were lower in isolated GH-deficient patients than in multiple pituitary deficient patients.

CONCLUSIONS

The two groups of patients, treated specifically for their identified hormonal deficiencies, in the end had similar satisfactory reproductive results.

Gonadotropin-releasing hormone agonist analog (nafarelin): a useful diagnostic agent for the distinction of constitutional growth delay from hypogonadotropic hypogonadism

To determine the usefulness of a GnRH agonist analog as a diagnostic test to distinguish between constitutional delay of growth (CGD) in boys with Tanner stage I of sexual development and patients with hypogonadotropic hypogonadism (HH), we evaluated six boys (mean age 15 yr 4 m) and five HH patients (mean age 20 yr 4 m). In addition, 20 normal healthy men aged 21 yr to 50 yr received either nafarelin or GnRH followed two weeks later by the other test in order to compare the efficacy of each of these tests and to evaluate the optimal sampling times for the nafarelin test. All subjects were healthy, and had not received hormonal replacement for at least 2 months prior to enrollment in the study. Each man had four baseline blood samples before and at timed intervals following the administration of either GnRH or nafarelin. Each of the patients had blood withdrawn every 15 min during 12 h overnight followed by a single s.c. injection of nafarelin (1 microgram(s)/kg up to 100 microgram(s)), except two HH patients who did not have an overnight study. Blood samples were obtained at timed intervals for 24 h. LH, FSH, T and E2 were measured by RIA. Baseline concentrations of plasma LH, FSH and T were similar before the administration of either GnRH or nafarelin in the group of normal men. Peak stimulation of plasma LH, FSH and T released by nafarelin was significantly higher, and it took a longer time to reach the peak maximum, than after GnRH (p < 0.001). Mean nocturnal LH was 5.5 +/- 0.9 IU/I for the CGD group, and 2.7 +/- 0.7 IU/I for HH (p < 0.02). Mean nocturnal FSH was 5.1 +/- 1.0 and 2.5 +/- 0.2 IU/I whereas mean nocturnal T concentrations were 4.2 +/- 0.8 and 0.7 +/- 0.2 nmol/I (CGD vs HH, respectively, p < 0.02). Peak LH responses to nafarelin were 36.9 +/- 8.9 IU/I for the CGD group, and 7.0 +/- 2.0 IU/I for the HH group (p < 0.001). Peak FSH released by nafarelin was 14.2 +/- 2.4 IU/I for the CGD group and 4.8 +/- 2.0 IU/I for the HH group (p < 0.02). Peak T was reached 24 h following nafarelin injection and was 5.7 +/- 1.7 nmol/I for the CGD group and 0.3 +/- 0.2 nmol/I for the HH group (p < 0.001). The results obtained indicate that in early stages of puberty (before detectable changes of sexual maturation) the nafarelin test, with measurements of LH, FSH and T in blood or in urine, is superior to and more practical than overnight hormonal estimates to clearly distinguish CGD from HH.

Use of the gonadotropin-releasing hormone agonist triptorelin in the diagnosis of delayed puberty in boys

To differentiate gonadotropin deficiency from delayed puberty in teenage boys, 0.1 mg/m2 of triptorelin, a gonadotropin-releasing hormone agonist, was administered subcutaneously at 4 AM. Serum gonadotropins and testosterone levels were determined at baseline and 4 hours after the injection. The increase in blood gonadotropin and testosterone levels was significantly greater in patients with delayed puberty than in those with gonadotropin deficiency.

Delayed puberty in uremia: pituitary-gonadal function during short-term pulsatile luteinizing hormone-releasing hormone administration

Pubertal development is frequently delayed or disordered in children with chronic renal failure. Both neuroendocrine and peripheral alterations due to uremia have been hypothesized to explain the impairment in the pituitary gonadal axis. The aim of the present study was to evaluate quantitative (immunological) and qualitative (biological) LH secretion, as well as FSH and sex steroids, before and during 7 days of sc LHRH administration (136-150 ng/kg bw every 120 min) in 5 uremic children (13.1-14.8 yr) with delayed puberty. Six nonuremic children (13.2-17.8 yr) with delayed puberty underwent the same schedule and served as control group. On day 0 mean immunoreactive LH (I-LH) levels were higher in uremic (4.5 +/- 0.9 mIU/ml) than in nonuremic (1.9 +/- 03 mIU/ml; p < 0.05) subjects while no differences were observed in bioactive LH (B-LH) levels (2.9 +/- 0.7 mIU/ml vs 2.4 +/- 0.3 mIU/ml). In both groups of subjects testosterone was at prepubertal levels. Spontaneous I-LH and B-LH pulses were observed sporadically in both uremic and nonuremic subjects. Short-term pulsatile LHRH administration induced significant increases in B-LH, I-LH, FSH and testosterone. The B/I LH ratio increased from day 0 (0.7 +/- 0.2) to day 7 (1.3 +/- 0.4; p < 0.05) in uremics while it showed wide fluctuations in nonuremic subjects. On day 7, 4 uremic and 5 nonuremic subjects showed a pulsatile release of B-LH after exogenous LHRH pulses. Our data document that in uremia there are qualitative as well as quantitative abnormalities in pituitary gonadal secretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of gonadotropin responses to synthetic gonadotropin-releasing hormone in girls with idiopathic hypopituitarism

We hypothesized that prepubertal girls with gonadotropin deficiency would produce less follicle-stimulating hormone (FSH) in response to synthetic gonadotropin-releasing hormone (GnRH) than would gonadotropin-sufficient children. To test this hypothesis, we performed 103 GnRH tests serially in 21 children who had idiopathic hypopituitarism with growth hormone deficiency. We tried to predict whether puberty would occur in the 17 girls with bone ages of 8 years or less. Of these 17 girls, 4 failed to have spontaneous secondary sexual characteristics by age 16 1/2 years, and 12 had spontaneous complete pubertal development. One girl had incomplete pubertal maturation with partial gonadotropin deficiency; her results were combined with those of the girls who had no spontaneous pubertal development. With increasing bone age, the girls with complete pubertal development had a decrease in the increment of FSH released in response to GnRH, although basal gonadotropin concentrations did not change. For GnRH tests performed at bone ages of 8 years or less, basal luteinizing hormone (LH) values did not differ between girls with complete puberty and those with absent or incomplete puberty. However, basal FSH and the incremental response of LH and FSH to GnRH were greater in those with complete puberty. Only two girls with prepubertal bone ages at the time of testing, who subsequently had complete puberty, had incremental FSH responses to GnRH that were less than 5 IU/L. Individual incremental LH responses to GnRH did not discriminate well between groups. None of the girls with adrenocorticotropic hormone deficiency, either originally or subsequently, had spontaneous puberty, but 4 of 12 girls with thyrotropin deficiency, either originally or subsequently, had complete puberty. We conclude that a significant increase in GnRH-stimulated FSH suggests that spontaneous pubertal development will occur in girls with idiopathic hypopituitarism. However, a low FSH response to GnRH may not be diagnostic of gonadotropin deficiency.

Gonadotropin-releasing hormone agonist testing of pituitary-gonadal function

The development of gonadotropin-releasing hormone (GnRH) agonists has provided a unique means to functionally assess the pituitary-gonadal axis in both males and females. These agonists, when given in a dose sufficient to stimulate the gonadotropes and induce a gonadal steroid response, have provided insights into normal reproductive physiology, hyperandrogenic conditions such as the polycystic ovary syndrome (PCOS), and disorders of pubertal development. This review provides an overview of the use of such agonists as probes of the functional status of the pituitary-gonadal axis in both normal and abnormal reproductive states.