Precocious Puberty, GnRH Stimulation Test and Monitoring GnRH Analog Therapy

Effectiveness of the triptorelin stimulation test compared with the classic gonadotropin-releasing hormone stimulation test in diagnosing central precocious puberty in girls

PURPOSE

The gonadotropin-releasing hormone (GnRH) stimulation test is the gold standard for diagnosing central precocious puberty (CPP). Gonadorelin (Relefact) is used for the test but is not always readily available; triptorelin is used as an alternative. The purpose of this study was to evaluate the diagnostic validity of the triptorelin test compared with the GnRH test in the diagnosis of CPP in girls.

METHODS

This retrospective study included 100 girls with premature thelarche (PT) who underwent a hypothalamic-pituitary-gonadal axis evaluation. In the overall group, 50 girls were tested with intravenous gonadorelin (Relefact) and 50 girls were tested with subcutaneous triptorelin acetate (Decapeptyl). Luteinizing hormone (LH) and follicle-stimulating hormone levels were measured at baseline and 30, 45, 60, and 90 minutes after gonadorelin injection or 30, 60, 90, and 120 minutes after triptorelin injection.

RESULTS

Clinical characteristics of age, height, weight, body mass index, and bone age were similar between the 2 groups. The highest LH level was reached 60 minutes after stimulation in both groups. Approximately 20% of the gonadorelin group and 24% of the triptorelin group were diagnosed with CPP (P=0.52). Among those diagnosed with CPP, the mean peak LH concentrations were 8.15 mIU/mL and 9.73 mIU/mL in the gonadorelin and triptorelin groups, respectively.

CONCLUSION

The triptorelin test showed similar trends of LH elevation and diagnostic rate compared with the traditional GnRH test for diagnosing CPP. This suggests that the triptorelin test may be a valid alternative to the GnRH test for differentiating CPP from self-limiting PT. Our study also demonstrated that a triptorelin stimulation test for up to 120 minutes was sufficient to diagnose CPP.

Effectiveness of basal LH in monitoring central precocious puberty treatment in girls

OBJECTIVES

Treatment of central precocious puberty (CPP) is based on administration of GnRH agonists in order to suppress hypothalamic-pituitary-gonadal axis and thus induce the stabilization or regression of pubertal development. Our aim was to determine whether the single basal serum LH and/or FSH concentration could be an effective tool to assess the efficacy of treatment to suppress activation of hypothalamic-pituitary axis.

PATIENTS AND METHODS

Serum LH and FSH were measured before and after the GnRH injection, as well as E2 basal levels in 60 girls with documented idiopathic CPP at diagnosis and 18 and 30 months after the beginning of therapy.

RESULTS

At diagnosis, peaks of >5 IU/L of LH and of FSH were observed in 100 and 91.6% of girls, respectively, with basal LH values of <1 IU/L in 70% and basal FSH levels of <1 IU/L in 10%. E2 were <20 pg/mL in 36.6%. After 18 months, a suppressed peak (i.e. <3 IU/L) was recorded in 85% of girls (p<0.01) for LH and in 98.3% for FSH (p<0.01). Basal LH <1 IU/L was detected in 85% (p<0.01) and basal FSH ≤1 IU/L in 40% (p<0.01). Serum E2 ≤20 pg/mL was recorded in 61.6% (p<0.01). After 30 months, all patients showed LH suppressed peak (p<0.01) and 98.3% suppressed FSH peak (p<0.01). 100% showed basal LH concentrations <1 IU/L (p<0.01) and 38.3% FSH basal values <1 UI/mL (p<0.01). E2 ≤20 pg/mL was observed in 32.72% (p=NS).

CONCLUSIONS

Basal LH values are a reliable indicator of the efficacy of GnRHa therapy after 30 months of GnRHa therapy.

Gonadotropin-releasing hormone stimulation test and diagnostic cutoff in precocious puberty: a mini review

The gonadotropin-releasing hormone (GnRH) stimulation test is a valuable tool in diagnosing and differentiating causes of early pubertal occurrences. Utility of the test can be limited in some instances, however, including the early phases of pubertal hypothalamic-pituitary-gonadal axis activation, in girls showing commonly overlapping pictures, and in obese children due to excess circulating estrogen that suppresses luteinizing hormone (LH). A lack of consistent baseline and stimulated gonadotropin cutoffs observed in different studies also contributes to limitations in testing. Nevertheless, early detection of true pathological causes for pubertal disorders is needed to allow prompt treatment and better prognosis. While basal LH can be beneficial as a good screening tool for detecting pubertal disorder, it does not preclude the need for GnRH testing. The aim of this review was to highlight the role of GnRH stimulation tests and varying testing cutoffs in diagnosis of precocious puberty and its classification.

Influence of the hypothalamus-pituitary-gonadal axis reactivation and pubertal hormones on gray matter volume in early pubertal girls

OBJECTIVE

Puberty is a sensitive period of brain development accompany with pubertal hormones fluctuation. However, the underlying mechanisms of the impact of hypothalamus-pituitary-gonadal (HPG) axis reactivation and associated elevated pubertal hormones on brain structure are still unclear. Here, we investigated the brain structure differences between girls with and without HPG axis reactivation and the influence of pubertal hormones on these brain regions.

METHODS

126 girls aged 8-9.5 years underwent a gonadotropin-releasing hormone (GnRH) stimulation test to identify the HPG axis status and categorized into HPG+ group (n = 80) and HPG- group (n = 46). T1-weighted gradient echo three dimensional MRI was performed using a 3.0-Tesla scanner to assess the difference in GMV between the two groups. Correlation analyses were conducted to explore the relations between the brain regions showing significant GMV differences and serum hormone concentrations.

RESULT

The HPG+ group showed significantly higher GMV in the bilateral lingual gyrus and lower GMV within the right orbital inferior frontal gyrus compare to the HPG - group. Furthermore, GMV in the right orbital inferior frontal gyrus was positively associated with plasma concentrations of follicle stimulating hormone (FSH) in HPG+ group.

CONCLUSION

The present study suggests that the reactivated HPG axis could affects regional structural brain changes in early pubertal girls. FSH production play an important role in bilateral lingual gyrus, which are involved in vision processing, semantic processing and emotional expression.

Gray Matter Differences Between Premature Pubertal Girls With and Without the Reactivation of the Hypothalamic-Pituitary-Gonadal Axis

The onset of puberty and related hormones exerts significant effects on brain morphometric and psychosocial development. The biological mechanisms underlying how the reactivation of the hypothalamic-pituitary-gonadal (HPG) axis and puberty-related hormonal maturation sculpts human brain architecture remain elusive. To address this question, 105 premature pubertal girls (age 8-11 years) without menstruation underwent brain structural scanning on a 3T MR system, and the luteinizing hormone releasing hormone (LHRH) stimulation test was used to identify the reactivation of the HPG axis. Among the 105 girls, 63 were positive for HPG axis reactivation (HPG+), while the others showed negative (HPG-). Cortical thickness was calculated and compared between the two groups after adjusting for age. The brain regions showing inter-group differences were then extracted and correlated with the peak value of serum hormone after the LHRH stimulation test in entire sample. Compared to HPG- girls, HPG+ girls showed reduced cortical thickness mainly in the the right precuneus, right inferior temporal gyrus, and right superior frontal gyrus, while increased cortical thickness primarily in the left superior parietal lobe and right inferior parietal lobe. Linear-regression analysis revealed negative correlations between the cortical thickness of the right inferior parietal lobe with the peak value of FSH and the right precuneus with LH and E. These findings provide evidence to support the notion that the reactivation of HPG axis and changes of hormones during the early phase of hormonal maturation exert influences on the development of gray matter.

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.