Gonadotrophin response to LH-RH in boys with delayed growth and adolescence

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.

Pubertal disorders and bone maturation

Bone age (BA) indicates more clearly than chronologic age how far an individual has progressed toward full maturity, and predicts the potential for further growth. Single or serial skeletal age estimations help to confirm the diagnosis of normal puberty and normal pubertal variants such as constitutional delay of growth and puberty, premature therlache, and precocious adrenarche. BA can aid in the clinical workup of children whose sexual maturation is early or delayed. Although BA is considered a qualitative rather than quantitative measure, it serves to round out the clinical picture, providing information without which diagnosis could not be achieved.

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.

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

OBJECTIVE

To assess the efficacy of the gonadotropin-releasing hormone (GnRH) agonist buserelin in a stimulated gonadotropin test for the investigation of delayed puberty in males.

STUDY DESIGN

Prepubertal males (n = 31; age range, 10.3 to 17.2 years) were studied; buserelin (100 microg) was administered subcutaneously, with blood sampling at 0 and 4 hours for serum luteinizing hormone (LH) and follicle-stimulating hormone (FSH). At follow-up (mean, 4.2 years), 8/31 (26%) failed to progress into puberty, constituting hypogonadotropic hypogonadism (HH), but 23/31 (74%) had testicular enlargement (> or =8 mL) consistent with a normal hypothalamic-pituitary-gonadal (HPG) axis.

RESULTS

Stimulated serum LH response to buserelin was lower in males with HH (mean +/- standard error under the mean for HH, 1.4 +/- 0.5 U/L, compared with a normal HPG axis of 17.4 +/- 2.0 U/L; P < .0001). Stimulated serum FSH response was nondiscriminatory (HH, 7.7 +/- 2.2 U/L; normal HPG axis, 11.5 +/- 1.6 U/L; P = .27). All males with HH had a stimulated serum LH level <5 U/L, whereas only 1/23 with a normal HPG axis had a stimulated serum LH below this level. Using this value as the criterion for diagnosing HH, the buserelin stimulation test yielded a sensitivity of 100%, specificity of 96%, and positive predictive value of 89%.

CONCLUSIONS

The buserelin stimulation test is a highly specific and sensitive GnRH agonist test for the investigation of males with delayed puberty.

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.

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.

The combined pituitary function test in children: an evaluation of the clinical usefulness of TRH and LHRH stimulation tests through a retrospective analysis of one hundred and twenty six cases

OBJECTIVE

The combined pituitary function test is routinely used in the endocrine investigation of short children. The TRH and luteinising hormone-releasing hormone (LHRH) response tests have been shown to be of minimal value in adults. We have evaluated the clinical utility of these tests in the context of combined pituitary function testing in children.

DESIGN

A retrospective analysis of basal hormone measurements and pituitary stimulation tests in relation to clinical assessment of pituitary function.

PATIENTS

One hundred and twenty-six children, 82 boys and 44 girls, aged 2-17 years, who had undergone pituitary function testing were studied.

RESULTS

The TSH response to TRH stimulation correlated directly with basal plasma TSH but not basal plasma total T4. In patients with an impaired response to stimulation, basal TSH concentrations were <2.0 mIU/l and significantly lower than in patients with a normal response (P < 0.0001). An impaired response to TRH stimulation had a positive predictive value of 0.43 and a negative predictive value of 0.90 for the diagnosis of hypopituitarism. A basal TSH concentration of <2.0 mIU/l had a positive predictive value of 0.22 and a negative predictive value of 0.92. A low basal T4 (normal range 60-140 nmol/l) in combination with an inappropriately low or normal basal TSH was always associated with a diagnosis of hypopituitarism. The responses of plasma LH and FSH to LHRH stimulation correlated directly with basal plasma LH and FSH concentrations. Basal gonadotrophin concentrations, basal sex hormone concentrations or response to LHRH stimulation could not distinguish patients with constitutional delay of growth and puberty from those with hypopituitarism. There was no apparent relationship between either basal gonadotrophin concentrations or response to LHRH stimulation and clinical assessment of pituitary function. In patients ≥13 years with constitutional delay of growth and puberty the median and interquartile ranges of basal LH and FSH were 1.4 IU/l (0.7-3.6) and 2.6 IU/l (2.2-5.2) respectively. The three hypopituitary patients in this study with chronological age ≥13 years had undetectable concentrations of both gonadotrophins. The response of LH and FSH to LHRH stimulation was significantly lower in patients ≥13 years with clinical hypopituitarism than in those with intact pituitary function (P <0.02).

CONCLUSION

TRH and LHRH tests in children with short stature appear to have little value over and above the baseline hormone measurements. An abnormal response to hormone stimulation is not diagnostic of hypothalamic-pituitary disease. We have demonstrated that neither TRH nor LHRH stimulation tests should be routinely used in the investigation of children with short stature.

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.

Transient sexual precocity and ovarian cysts

Nine girls presenting under the age of 7 years with unsustained sexual precocity are described. Large ovarian cysts were detected by ultrasound in three and laparotomy in one. In two girls the symptoms resolved after surgical removal of the cyst; the other seven had spontaneous remission of symptoms, but in two of these transient breast development and bleeding recurred: further ovarian cyst formation was found in one of these patients. Endocrine studies performed before resolution of the cysts showed raised plasma oestradiol concentrations (64 to 440 pmol/l) in three girls and no appreciable rise in plasma luteinising hormone after gonadotrophin releasing hormone stimulation in two. We conclude that ovarian cyst formation with spontaneous resolution may cause transient sexual precocity in girls, and that ultrasound examination is an effective means of diagnosing and following these patients.

Endocrine function, morbidity, and mortality after surgery for craniopharyngioma

The records of 59 children with craniopharyngioma first treated between 1960 and 1980 were reviewed. There was a high incidence of postoperative growth hormone deficiency (43 of 43), andrenocorticortopin deficiency (26 of 36), thyrotrophin deficiency (13 of 20), gonadotrophin deficiency (15 of 16), and diabetes insipidus (44 of 58). Fifteen patients have died: diabetes insipidus was a contributory factor in 5 patients who died within the first 4 months of surgery; and 8 further children died unexpectedly after the postoperative period, probably as a result of anterior pituitary insufficiency. In addition, hypopituitarism led to medical emergencies in 12, 9 of whom had symptomatic hypoglycaemia. These findings illustrate the high incidence of pituitary deficits which follow current methods for treating childhood craniopharyngioma, and the long-term risks associated with these deficits.

Growth and pubertal development in five boys with Noonan's syndrome

Five boys, each with at least 4 features characteristic of Noonan's syndrome, were studied throughout childhood. In each the height was on or below the 3rd centile. Height velocity was essentially normal during the prepubertal period whereas bone age and pubertal development were delayed. Four boys had cryptorchidism and in 2 no testicular enlargement or spontaneous puberty occurred, necessitating testosterone replacement. Plasma concentrations of luteinising hormone and follicle-stimulating hormone before and after stimulation with luteinising hormone-releasing hormone were increased in 4 of the boys. These findings are consistent with primary gonadal failure associated with impaired spermatogenesis.