Original article
Thyroid Outcome During Long-Term Gonadotropin-Releasing Hormone Agonist Treatments for Idiopathic Precocious Puberty

https://doi.org/10.1016/j.jadohealth.2006.09.024Get rights and content

Abstract

Purpose

To examine the effects of long-term gonadotropin-releasing hormone agonist (GnRHa) administration on thyroid function in children affected by central precocious puberty (CPP).

Methods

We retrospectively evaluated circulating thyroid hormones in 73 GnRHa-treated girls who were diagnosed with idiopathic CPP. Monthly depot injections (.1 mg/body kg) of leuprorelin acetate (LA) and of triptorelin (TR) were continuously administered for 40.4 ± .7 months to 34 and 39 CPP patients, respectively. Serum levels of thyrotropin (TSH), free triiodothyronine (FT3), free thyroxine (FT4), and thyroid antibodies were determined at baseline and after 6, 12, 18, 24, 30, 36, and 40 months of GnRHa administration.

Results

While there was no difference in FT4 release (p > .05), FT3 levels significantly declined during both LA and TR treatments from untreated baseline (p < .05). Opposite to circulating FT4 and FT3 values (p > .05), FT3/FT4 ratio was significantly different among LA and TR groups (p < .05). Both GnRHa treatments did not affect TSH secretion (p > .05); however, LA induced lower TSH values than TR (p < .05).

Conclusions

There is no evidence of thyroid dysfunction during both GnRHa treatments, though changes in TSH, FT3, and FT3/FT4 ratios were noted. Finally, monitoring of thyroid activity during GnRHa administration is not required.

Section snippets

Patient population

To assess thyroid function during long-term GnRHa treatment, we retrospectively analyzed clinical data of CPP girls attended as outpatients at the Pediatric Endocrine Center of Pisa between 1998 and 2004. After local Institutional Review Board approval, informed consent was obtained for all parents of patients prior to the study. The inclusion criteria in the study were: (1) being a female affected by idiopathic CPP; (2) being continuously GnRHa-treated for more than 37 months; (3) one IM

Results

At the start of GnRHa treatment, the auxological characteristics of CPP subjects treated with TR and LA were statistically similar (p > .05; Table 1). During GnRHa treatment, down-regulation of the pituitary-gonadal axis was confirmed by suppressed LH, FSH, and E2 levels. They fell significantly during TR treatment with serum values of .76 ± .5 IU/L, 1.23 ± .6 IU/L, and 13.6 ± 1.5 pg/mL, respectively (p < .001 for all three hormones as compared with their levels before TR treatment). During LA

Discussion

GnRHa drugs are used in the treatment of a wide variety of sex hormone-related diseases, including uterine leiomyoma, endometriosis, prostate, and breast cancer [1], [2]. In the pediatric population, GnRHa drugs are mostly used to delay the effects of premature awakening of the hypothalamic-pituitary-gonadal axis in children with CPP [3], [5], [6].

In our Pediatric Endocrine Center, CPP patients are determined for GnRHa suppression of gonadotropin-ovary axis every 4–6 months by circulating LH,

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