Allopregnanolone levels decrease after gonadotropin-releasing hormone analog stimulation test in girls with central precocious puberty

Initiation of the Hypothalamic-Pituitary-Gonadal Axis in Young Girls Undergoing Central Precocious Puberty Exerts Remodeling Effects on the Prefrontal Cortex

Central precocious puberty (CPP) has been shown to exert significant effects on psychosocial development. These early puberty-related hormones and psychosocial functional changes are considered to be associated with specific brain development. However, the biological mechanisms underlying the sculpting of human brain architecture and modulation of psychosocial transformation by puberty-related hormonal maturation remain elusive, especially during the early phase of CPP. The current investigation aims to specify the brain regions in which early hormone-related maturation effects occur during CPP and their relationships with psychological functions. 65 young girls (aged 4.3-8.0 years) underwent structural imaging on a 3T MR system, completed psychological tests and performed the gonadotropin-releasing hormone (GnRH) stimulation test to identify hormonal manifestations of hypothalamic-pituitary-gonadal axis (HPG axis) activation. Based on the GnRH test, 28 young girls were identified with CPP, whereas the other 37 girls were identified with non-central precocious puberty (NCPP). Cortical parameters were calculated and compared between the two groups after adjusting for age, weight, and height. Brain regions showing group differences were extracted and correlated with serum hormone levels and psychological parameters. The CPP girls showed thinner cortices primarily in the right rostral middle frontal cortex. This morphological difference was positively correlated with stimulated estradiol (E2) levels. Further, higher E2 levels were significantly associated with higher hyperactivity scores. Premature HPG axis activation in CPP girls at an early stage appears to exert remodeling effects on brain anatomy, primarily in the prefrontal cortex, which may affect psychological development following the emergence of robust changes in sex hormones.

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

CONTEXT

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

OBJECTIVE

The objective of the study was to determine the normal relationship of pubertal hormone responses to sleep and to GnRH agonist (GnRHag) challenge across the female pubertal transition.

DESIGN/SETTING

This was a prospective study in a General Clinical Research Center.

PARTICIPANTS

Sixty-two healthy 6- to 13-year-old volunteer girls participated in the study.

INTERVENTIONS

Interventions included overnight blood sampling followed by GnRHag (leuprolide acetate) injection.

PRIMARY OUTCOME VARIABLES

The primary outcome variables included LH, FSH, and estradiol.

RESULTS

LH levels rose steadily during sleep and after GnRHag throughout the prepubertal years. The LH response to sleep and GnRHag correlated well across groups (eg, r = 0.807, peak vs 4 h post-GnRHag value); however, this correlation was less robust than in boys (r = 0.964, P < .01). Sleep peak LH of 1.3 U/L or greater had 85% sensitivity and 2.1 U/L or greater 96% specificity for detecting puberty (thelarche). The LH 1-hour post-GnRHag value of 3.2 U/L or greater had 95% sensitivity and 5.5 U/L or greater 96% specificity for detecting puberty. Girls entered puberty at lower LH levels than boys. FSH levels rose day and night during the prepubertal years to reach 1.0 U/L or greater during puberty but discriminated puberty poorly. Estradiol of 34 pg/mL or greater at 20-24 hours after GnRHag was 95% sensitive and 60 pg/mL or greater was 95% specific for puberty. Thirty-six percent of overweight early pubertal girls had meager hormonal evidence of puberty.

CONCLUSIONS

These data suggest that sleep-related pubertal hormone levels critical for puberty are normally reflected in the responses to GnRHag testing across the normal female pubertal transition. Inconsistencies between clinical and hormonal staging may arise from peripubertal cyclicity of neuroendocrine function and from excess adiposity.

High diagnostic accuracy of subcutaneous Triptorelin test compared with GnRH test for diagnosing central precocious puberty in girls

CONTEXT

The GnRH test is the gold standard to confirm the diagnosis of central precocious puberty (CPP); however, this compound is not always readily available. Diagnostic accuracy of subcutaneous GnRH analogues tests compared to classical GnRH test has not been reported.

OBJECTIVE

To evaluate the diagnostic accuracy of Triptorelin test (index test) compared to the GnRH test (reference test) in girls with suspicion of CPP.

DESIGN

A prospective, case-control, randomized clinical trial was performed. CPP or precocious thelarche (PT) was diagnosed according to maximal LH response to GnRH test and clinical characteristics during follow-up.

PATIENTS AND INTERVENTIONS

Forty-six girls with premature breast development randomly underwent two tests: (i) intravenous GnRH 100 μg, (ii) subcutaneous Triptorelin acetate (0.1 mg/m(2), to a maximum of 0.1 mg) with blood sampling at 0, 3 and 24 h for LH, FSH and estradiol ascertainment.

MEASUREMENTS

Gonadotrophins and estradiol responses to Triptorelin test were measured by ultrasensitive assays.

RESULTS

Clinical features were similar between CPP (n = 33) and PT (n = 13) groups. Using receiver operating characteristic curves, maximal LH response (LH-3 h) under Triptorelin test ≥ 7 IU/l by immunofluorometric assay (IFMA) or ≥ 8 IU/l by electrochemiluminescence immunoassay (ECLIA) confirmed the diagnosis of CPP with specificity of 1.00 (95% CI: 0.75-1.00) and sensitivity 0.76 (95% CI: 0.58-0.89). Considering either LH-3 h or maximal estradiol response at 24 h (cut-off value, 295 pm), maintaining the specificity at 1.00, the test sensitivity increased to 0.94 (95% CI: 0.80-0.99) and the diagnostic efficiency to 96%.

CONCLUSION

The Triptorelin test had high accuracy for the differential diagnosis of CPP vs PT in girls providing a valid alternative to the classical GnRH test. This test also allowed a comprehensive evaluation of the pituitary-ovarian axis.

Contemporary issues in precocious puberty

Precocious puberty poses significant diagnostic and therapeutic challenge to the physician. Recent advances in the understanding of pathophysiology of precocious puberty have resulted in improved management. Timely intervention is mandatory to achieve successful outcome. The identification of critical role of KISS-1-kisspeptin-GPR54 system has gone a long way to provide an insight into pubertal physiology. It is likely that the system would become an important diagnostic and therapeutic target in children with precocious puberty. Epidemiological studies point toward earlier thelarche. This is, however, associated with slower progression as the age of menarche is static. These changes have led to suggestions of lowering the age cutoffs for precocious puberty in girls. New developments in assessment of precocious puberty including gonadotropin releasing hormone (GnRH) agonist test have made characterization of precocious puberty easier. Longstanding GnRH analogs have become the mainstay of treatment of gonadotropin-dependent precocious puberty, while aromatase inhibitors and inhibitors of sex hormone action are increasingly being used in gonadotropin-independent precocious puberty.