Evaluation of the buserelin stimulation test in diagnosing gonadotropin deficiency in males with delayed puberty

Mosaic trisomy 13 and constitutional delay in puberty

Patau syndrome is the third most frequent chromosomal trisomy, with an estimated mortality rate that is about 50 times higher than the general neonatal mortality rate. Trisomy 13 mosaicism is a subtype that may result in a milder form of the disease, potentially leading to a longer life expectancy in these patients, allowing them to reach puberty. In this report, we discuss the case of a young boy who was evaluated for delayed puberty and karyotyping revealed mosaicism for trisomy 13. A detailed history, physical examination and appropriate laboratory studies and imaging were performed that showed a picture of suggestive of hypogonadotropic hypogonadism and an abnormal male karyotype with mosaicism for trisomy 13. To date, there is no clear explanation to the association between trisomy 13 and gonadal axis, specifically with normal imaging of pituitary. We postulate that delayed puberty could be a clinical feature of mosaic trisomy 13.

[Clinical guidelines «Precocious puberty»]

The precocious puberty is an urgent problem of pediatric endocrinology characterized by clinical and pathogenetic heterogeneity. The appearance of secondary sex characteristics before the age of 8 years in girls and 9 years in boys requires timely diagnosis and the appointment of pathogenetically justified treatment in order to achieve the target indicators of final growth and prevent social deprivation. The developed clinical guidelines are the main working tool of the practitioner. They briefly and structurally present the main information about the epidemiology and modern classification of рrecocious puberty, methods of its diagnosis and treatment based on the principles of evidence-based medicine.

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.

Delayed puberty versus hypogonadism: a challenge for the pediatrician

Constitutional delay of growth and puberty (CDGP) is the most common cause of delayed puberty (DP), is mainly found in males, and is characterized by short stature and delayed skeletal maturation. A family history of the subject comprising the timing of puberty in the parents and physical examination may provide clues regarding the cause of DP. Delayed onset of puberty is rarely considered a disease in either sex. In fact, DP usually represents a common normal variant in pubertal timing, with favorable outcomes for final height and future reproductive capacity. In adolescents with CDGP, a linear growth delay occurs until immediately before the start of puberty, then the growth rate rapidly increases. Bone age is often delayed. CDGP is a diagnosis of exclusion; therefore, alternative causes of DP should be considered. Functional hypogonadotropic hypogonadism may be observed in patients with transient delay in hypothalamic-pituitary-gonadal axis maturation due to associated conditions including celiac disease, inflammatory bowel diseases, kidney insufficiency, and anorexia nervosa. Permanent hypogonadotropic hypogonadism (pHH) showing low serum value of testosterone or estradiol and blunted follicle-stimulating hormones (FSH) and luteinizing hormones (LH) levels may be due to abnormalities in the central nervous system. Therefore, magnetic resonance imaging is necessary to exclude morphological abnormalities and neoplasia. Moreover, pHH may be isolated, as observed in Kallmann syndrome, or associated with other hormone deficiencies, as found in panhypopituitarism. Baseline or gonadotropin-releasing hormone pituitary stimulated gonadotropin level is not sufficient to easily differentiate CDGP from pHH. Low serum testosterone in male patients and low estradiol values in female patients, associated with high serum FSH and LH levels, suggest a diagnosis of hypergonadotropic hypogonadism. A genetic analysis can reveal a chromosomal abnormality (e.g., Turner syndrome or Klinefelter syndrome). In cases where the adolescent with CDGP is experiencing psychological difficulties, treatment should be recommended.

Role of Gonadotropin-releasing Hormone Stimulation Test in Diagnosing Gonadotropin Deficiency in Both Males and Females with Delayed Puberty

Background:

Delayed puberty can result either from constitutional delay of growth and puberty (CDP) or idiopathic hypogonadotropic hypogonadism (IHH). Gonadotropin-releasing hormone (GnRH) stimulation test has been generally accepted as a current method for diagnosing delayed puberty. The objective of this research was to assess the cut-off values and the efficacy of GnRH stimulation test in the diagnosis of delayed puberty in both males and females.

Methods:

A study of 91 IHH, 27 CDP patients, 6 prepubertal children, and 20 pubertal adults was undertaken. Blood samples were obtained at 0, 30, 60, and 120 min after GnRH administration and the levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were measured. For each parameter, the sensitivities and specificities were estimated, and the receiver operating characteristic (ROC) curves were constructed.

Results:

The ROC curves indicated that a serum basal LH <0.6 IU/L or peak LH <9.74 IU/L resulted in moderate sensitivity (73.8% or 80.0%) and specificity (90.9% or 86.4%) in the diagnosis of HH in males. Serum basal LH <0.85 IU/L or basal FSH <2.43 IU/L resulted in moderate sensitivity (80.0% or 100.0%) and specificity (75.0% or 50.0%) in the diagnosis of HH in females.

Conclusions:

Our data suggest that isolated use of the gonadorelin stimulation test is almost sufficient to discriminate between HH and CDP in males, but unnecessary in females. The most useful predictor is serum basal or peak LH to differentiate these two disorders in males, but serum basal LH or FSH in females.

Inhibin B plus LH vs GnRH agonist test for distinguishing constitutional delay of growth and puberty from isolated hypogonadotropic hypogonadism in boys

OBJECTIVE

The distinction between constitutional delay of growth and puberty (CDGP) and isolated hypogonadotropic hypogonadism (IHH) in males with delayed puberty is difficult but important for timely treatment. We assessed the accuracy of the GnRH agonist test (triptorelin 0·1 mg) in comparison with inhibin B alone or in combination with basal LH for the diagnosis of IHH.

PATIENTS AND MEASUREMENTS

Ninety-seven prepubertal males aged 13·7-17·5 year, with testicular volumes ≤4 ml, were examined every 6 months. CDGP was defined by a testicular volume ≥8 ml after 18 months, and IHH was defined by a testicular volume <5 ml after 24 months follow-up. Inhibin B concentrations were measured by ELISA, and LH concentrations were measured by CLIA.

RESULTS

At follow-up, the cohort comprised 52 boys with CDGP and nine with IHH. The other patients were lost for follow-up (n = 10), had not reached follow-up yet (n = 20) or did not reach a definite testicular volume (n = 6). Basal LH <0·3 IU/l, stimulated LH (4 h) <5·3 IU/l or inhibin B <111 pg/ml had 100% sensitivity for IHH. Only LH (4 h) <5·3 IU/l had a specificity of 100%, and the specificities of basal LH <0·3 IU/l (88%) or inhibin B <110 pg/ml (92%) were lower. The combination of LH <0·3 IU/l with inhibin B <111 pg/ml increased the specificity to 98·1%.

CONCLUSIONS

The LH response 4 h after GnRH agonist stimulation has an excellent accuracy for the diagnosis of IHH in prepubertal boys with delayed puberty. However, the measurement of inhibin B and basal LH in combination is a valid, reliable and less-invasive alternative test.

Comparison of detection of normal puberty in boys by a hormonal sleep test and a gonadotropin-releasing hormone agonist test

CONTEXT

The magnitude of sleep-related gonadotropin rise required to activate pubertal gonadal function is not established.

OBJECTIVE

Our objective was to determine the normal relationship between sleep-related pubertal hormone levels and pituitary-testicular responsiveness to a GnRH agonist (GnRHag) test across the pubertal transition. DESIGN/SETTING AND PARTICIPANTS: We conducted a prospective study in a General Clinical Research Center with healthy 9- to 15-yr-old volunteer boys.

INTERVENTIONS

INTERVENTIONS included overnight blood sampling followed by leuprolide acetate injection (10 μg/kg).

PRIMARY OUTCOME VARIABLES

LH, FSH, and testosterone levels were evaluated.

RESULTS

LH levels during sleep and post-GnRHag rose steadily during the late prepubertal years. Sleep peak LH correlated highly with the LH response to GnRHag across groups (r = 0.913). A sleep peak LH level of at least 3.7 U/liter predicted pubertal testicular activation with 100% accuracy. LH of at least 14.8 and at least 19.0 U/liter 4 h after GnRHag, respectively, predicted puberty with 100% sensitivity/94% specificity and 100% specificity/94% sensitivity. Overweight pubertal boys had transiently prolonged responses to GnRHag. FSH rose during both waking and sleeping hours during the prepubertal years, and all pubertal boys had an FSH level of at least 0.9 U/liter awake and at least 1.2 U/liter asleep. Sleep LH was more closely related than FSH to testicular size.

CONCLUSIONS

These data suggest that a critical LH level during sleep (≥3.7 U/liter) heralds the onset of pubertal virilization and that this level is predictable by LH of at least 14.8-19 U/liter 4 h after GnRHag. These data also suggest that LH stimulation of testicular androgen production plays a role in stimulating testicular tubule growth once a critical level of FSH is achieved.

Leuprolide stimulation testing for the evaluation of early female sexual maturation

CONTEXT

Low concentrations of serum LH and/or oestradiol (E(2)) in girls with early physical signs of precocious puberty pose a diagnostic challenge.

OBJECTIVE

To assess the diagnostic value of the leuprolide stimulation test in female precocious puberty.

DESIGN

Retrospective Chart Review.

SETTING

Outpatient clinic.

PATIENTS AND INTERVENTION

Thirty-nine girls, 6.9 (1.4) years, with premature stage II-III breast development, with or without pubarche, underwent stimulation testing with subcutaneous leuprolide (20 microg/kg) with the following hormonal measurements in serum: FSH, LH, oestradiol at baseline; FSH and LH at 1 and 2 h; oestradiol at 24 h. Twelve girls with isolated pubarche were also tested with leuprolide.

MAIN OUTCOME MEASURE

A pubertal hormonal pattern was defined as at least one of the following: a baseline serum level of LH > or = 0.3 U/l, a baseline oestradiol > or = 37 pmol/l (10 ng/l), a stimulated (peak) LH > or = 5.0 U/l, a stimulated oestradiol > or = 184 pmol/l (50 ng/l) to leuprolide. The hormonal response was related to the clinical course during a period of observation of at least 6 months.

RESULTS

Following leuprolide stimulation, the hormonal response was concordant with pubertal progression (n = 23) or lack thereof (n = 16) in all children. At baseline, pubertal serum concentrations of LH and/or oestradiol were associated with pubertal progression in all, while serum prepubertal LH and/or oestradiol concentrations were associated with pubertal progression in approximately 50% of the patients.

CONCLUSIONS

In girls with early clinical signs of precocious puberty and low serum concentrations of LH and oestradiol in random samples, the LH and oestradiol responses to leuprolide stimulation accurately predict pubertal progression.

Basal follicle-stimulating hormone and peak gonadotropin levels after gonadotropin-releasing hormone infusion show high diagnostic accuracy in boys with suspicion of hypogonadotropic hypogonadism

CONTEXT

Differential diagnosis between hypogonadotropic hypogonadism (HH) and constitutional delay of puberty in boys is challenging. Most tests use an acute GnRH stimulus, allowing only the release of previously synthesized gonadotropins. A constant GnRH infusion, inducing de novo gonadotropin synthesis, may allow a better discrimination.

OBJECTIVE

We evaluated the diagnostic accuracy of basal and peak gonadotropins after GnRH infusion, measured by ultrasensitive assays, to confirm the diagnosis in boys with suspected HH.

DESIGN AND SETTING

We conducted a validation study following Standards for Reporting of Diagnostic Accuracy criteria at a tertiary public hospital.

PATIENTS AND METHODS

A GnRH i.v. infusion test was performed in 32 boys. LH and FSH were determined by immunofluorometric assay at 0-120 min. DIAGNOSIS ASCERTAINMENT: The following diagnoses were ascertained: complete HH (n = 19; testes < 4 ml at 18 yr), partial HH (n = 6; testes enlargement remained arrested for > or = 1 yr or did not reach 15 ml), and constitutional delay of puberty (n = 7; testes > or = 15 ml at 18 yr).

MAIN OUTCOME MEASURES

Sensitivity, specificity, positive and negative predictive values, and diagnostic efficiency were assessed.

RESULTS

Basal FSH less than 1.2 IU/liter confirmed HH with specificity of 1.00 (95% confidence interval = 0.59-1.00), rendering GnRH infusion unnecessary. In patients with basal FSH of at least 1.2 IU/liter, the coexistence of peak FSH less than 4.6 IU/liter and peak LH less than 5.8 IU/liter after GnRH infusion had high specificity (1.00; 95% confidence interval = 0.59-1.00) and diagnostic efficiency (76.9%) for HH.

CONCLUSIONS

Basal FSH less than 1.2 IU/liter confirms HH, which precludes from further testing, reducing patient discomfort and healthcare system costs. In patients with basal FSH of at least 1.2 IU/liter, a GnRH infusion test has a high diagnostic efficiency.

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.

Androgen therapy for delayed male puberty

PURPOSE OF REVIEW

Delayed puberty in men is a commonly presenting problem to paediatricians and an understanding of the available evidence on cause, treatments and outcomes is important to guide practice.

RECENT FINDINGS

Understanding of the regulation of the onset of puberty is gradually unfolding, although the genetic factors that dictate the timing of puberty in individuals and families remain poorly elucidated. Mutations and polymorphisms in candidate genes are being actively studied and it is likely that there is significant overlap between traditional diagnostic categories. Also, environmental endocrine disruptors may interact with the genetic regulation of puberty. Delayed puberty may not always be a benign condition, with increased risks of failing to achieve target height, adverse psychological and educational consequences, delayed sexual and psychosocial integration into society and effects on skeletal proportions and bone mass reported. Appropriate evaluation and follow-up is needed to guide clinical practice, particularly to distinguish constitutional delay in growth and puberty from that associated with other medical disease or permanent disorders.

SUMMARY

In milder cases of delayed puberty, treatment is often not required; however, considerable evidence exists for the efficacy and safety of short courses of low-dose testosterone therapy for appropriately selected individuals. This treatment is associated with high levels of patient satisfaction. There is not yet sufficient evidence for the routine use of other therapies (e.g. growth hormone, aromatase inhibitors) for constitutional delay in growth and puberty and better characterization of cause may lead to more targeted individual therapy.

Endocrinology of male puberty

PURPOSE OF REVIEW

To review recent information leading to a better understanding of the endocrinology of male puberty, including information from earlier stages of life.

RECENT FINDINGS

Differences in relative levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in the neonatal period have been further described, as well as changes in inhibin B and anti-Müllerian hormone levels. Studies among men with congenital hypogonadotropic hypogonadism suggest a role for the 'minipuberty of infancy' in inhibin B levels. Gonadotropin-releasing hormone analog-stimulated LH levels at the age of puberty may be useful in diagnosing hypogonadotropic hypogonadism. Inhibin B levels are likewise useful in monitoring spermatogenic activity.

SUMMARY

Data from fetal life (men born small for gestational age with evidence of a defect in steroidogenesis, relatively high LH:FSH ratio among very premature boys), neonatal period (attenuated rise of inhibin B after rFSH stimulation among men with congenital hypogonadotropic hypogonadism), and puberty (often demonstrable by LH levels alone, progressive rise of insulin-like factor 3 levels, and decrease of anti-Müllerian hormone levels as a consequence of FSH and LH stimulation), all enhance the understanding of the physiology of puberty.

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.