The Diagnostic Utility of the Triptorelin Stimulation Test Compared to the Standard Gonadotropin-Releasing Hormone Stimulation Test in Children with Idiopathic Central Precocious Puberty.

BACKGROUND

Central precocious puberty (CPP) is diagnosed through a combination of clinical, auxological, and biochemical parameters, with pharmacological stimulation tests considered the diagnostic gold standard. In recent years, triptorelin, a long-acting Gonadotropin-Releasing Hormone (GnRH) analog, has been increasingly adopted in clinical practice due to limited availability of native GnRH.

OBJECTIVE

To compare the clinical, auxological, and hormonal profiles of girls diagnosed with idiopathic CPP using either the classical GnRH stimulation test or the triptorelin test.

METHODS

This retrospective study included 136 female patients diagnosed with CPP and followed for at least two years at a single pediatric endocrinology unit. Of these, 101 underwent a GnRH stimulation test, and 35 were assessed using the triptorelin test. Baseline and stimulated hormonal parameters, growth data, and IGF-1 levels were collected. A multivariate linear regression model was used to explore the influence of age, test type, and other covariates on the LH peak response.

RESULTS

Anthropometric and baseline hormonal parameters were comparable between the two groups. The LH peak was significantly higher in the GnRH group (9.8 ± 3.1 IU/L at 60 min) than in the triptorelin group (6.8 ± 2.4 IU/L at 4 h). FSH levels were also significantly lower following triptorelin stimulation (p = 0.004), while the LH/FSH ratio did not differ significantly. Multivariate analysis confirmed that triptorelin was associated with a lower LH peak (β = -2.2, p = 0.008), particularly in younger patients, with a significant interaction between age and test type (β = 0.6, p = 0.022).

CONCLUSIONS

Both GnRH and triptorelin stimulation tests are valid tools for CPP diagnosis. However, the GnRH test appears to elicit a more robust LH response, especially in younger patients, whereas the triptorelin test is associated with delayed and lower LH peaks.