The metoclopramide test: a useful tool with the luteinizing hormone-releasing hormone test in distinguishing between constitutional delay of puberty and hypogonadotropic hypogonadism

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.

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.

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.