Thyroid outcome during long-term gonadotropin-releasing hormone agonist treatments for idiopathic precocious puberty

The effect of gonadotropin-releasing hormone analog treatment on the endocrine system in central precocious puberty patients: a meta-analysis

OBJECTIVES

Gonadotropin-releasing hormone (GnRHa) is the first choice for the treatment of patients with central precocious puberty (CPP). However, the effects of GnRHa on the endocrine system of CPP patients, including insulin sensitivity, lipid level, thyroid function, bone mineral density (BMD), and testosterone (T) level, are currently contradictory. Therefore, the long-term safety of GnRHa therapy remains controversial.

CONTENT

A systematic literature search was performed using PubMed, Embase, Cochrane Library, and CNKI databases. The changes in HOMA-IR, TG, LDL-C, HDL-C, TSH, FT3, FT4, T, and BMD in CPP patients before and after GnRHa treatment were compared by meta-analysis. As the heterogeneity between studies, we estimated standard deviation mean differences (SMDs) and 95 % confidence intervals (CIs) using a random-effects model. Egger's test was used to assess publication bias.

SUMMARY

A total of 22 studies were included in our meta-analysis. Compared with before GnRHa treatment, there were no statistically significant differences in endocrine indicators including HOMA-IR, TG, LDL-C, HDL-C, TSH, FT4, FT3, T, and BMD of CPP patients treated with GnRHa.

OUTLOOK

Treatment with GnRHa for central precocious puberty will not increase the adverse effect on the endocrine system.

A New Perspective on Thyroid Hormones: Crosstalk with Reproductive Hormones in Females

Accumulating evidence has shown that thyroid hormones (THs) are vital for female reproductive system homeostasis. THs regulate the reproductive functions through thyroid hormone receptors (THRs)-mediated genomic- and integrin-receptor-associated nongenomic mechanisms, depending on TH ligand status and DNA level, as well as transcription and extra-nuclear signaling transduction activities. These processes involve the binding of THs to intracellular THRs and steroid hormone receptors or membrane receptors and the recruitment of hormone-response elements. In addition, THs and other reproductive hormones can activate common signaling pathways due to their structural similarity and shared DNA consensus sequences among thyroid, peptide, and protein hormones and their receptors, thus constituting a complex and reciprocal interaction network. Moreover, THs not only indirectly affect the synthesis, secretion, and action of reproductive hormones, but are also regulated by these hormones at the same time. This crosstalk may be one of the pivotal factors regulating female reproductive behavior and hormone-related diseases, including tumors. Elucidating the interaction mechanism among the aforementioned hormones will contribute to apprehending the etiology of female reproductive diseases, shedding new light on the treatment of gynecological disorders.

Is gonadotropin-releasing hormone agonist usage really leading to thyroid dysfunction?

Objectives

Gonadotropin-releasing hormone agonist (GnRHa) could influence the levels of sex hormones and thyroid hormones. The aim of this study was to investigate the effect of GnRHa on thyroid function.

Materials and methods

The data of the patients were collected from the registrations of July 2014–October 2014. A total of 41 women who underwent one-time IVF cyclus were evaluated in this cross-sectional study. The patients were categorized into two groups according to the serum T₃, T₄, and TSH levels before and 2 weeks’ after the administration of GnRHa.

Results

Mean basal TSH and mean TSH levels on hCG day were 1.98 ± 0.77 and 1.75 ± 0.70, respectively. The difference between the two groups was statistically significant (p < 0.05). GnRHa did not lead to statistically significant difference on serum-free T₃ and T₄ levels.

Conclusions

In conclusion, our results demonstrate that GnRHa led to a decrease on serum TSH level. Serum-free T₃ and T₄ levels were remained unchanged and this might be due to early measurement of the hormone levels (just 2 weeks later from GnRHa administration).

Three cases of transient hyperthyroidism after triptorelin treatment - case report and literature review

The impacts of gonadtropin-releasing hormone (GnRH) agonists on thyroid function have long been observed and the conclusions were controversial. We here reported three cases of transient hyperthyroidisms after triptorelin therapy. The three patients showed decreased thyroid-stimulating hormone (TSH), with or without elevated free triiodothyronine (FT3) and free thyroxine (FT4) 2 weeks after injection of triptorelin. Thyroid-specific autoantibody assays showed antithyroid microsome autoantibody (TMAb) and (or) antithyroglobulin autoantibody (TgAb) were positive in two patients while and antithyrotropin receptor autoantibody (TRAb) were negative in all three cases. One patient with all thyroid-specific autoantibodies negative showed enlarged thyroid in thyroid ultrasound scanning. Only mild symptoms of hyperthyroidism presented in one patient. Four weeks after triptorelin injection, thyroid function returned to normal in all three patients. These observations indicated transient hyperthyroidism due to thyroid destruction in patients receive triptorelin therapy. The hyperthyroidism was most possibly due to onset of the autoimmune thyroiditis, emphasizing monitoring thyroid function during triptorelin treatment in females.

Comparative aspects of GnRH-Stimulated signal transduction in the vertebrate pituitary - Contributions from teleost model systems

Gonadotropin-releasing hormone (GnRH) is a major regulator of reproduction through actions on pituitary gonadotropin release and synthesis. Although it is often thought that pituitary cells are exposed to only one GnRH, multiple GnRH forms are delivered to the pituitary of teleost fishes; interestingly this can include the cGnRH-II form usually thought to be non-hypophysiotropic. GnRHs can regulate other pituitary cell-types, both directly as well as indirectly, and multiple GnRH receptors (GnRHRs) may also be expressed in the pituitary, and even within a single pituitary cell-type. Literature on the differential actions of native GnRH isoforms in primary pituitary cells is largely derived from teleost fishes. This review will outline the diversity and complexity of GnRH-GnRHR signal transduction found within vertebrate gonadotropes as well as extra-gonadotropic sites with special emphasis on comparative studies from fish models. The implications that GnRHR transduction mechanisms are GnRH isoform-, function-, and cell-specific are also discussed.

Serum thyroid hormone levels in healthy children from birth to adulthood and in short children born small for gestational age

CONTEXT

Age-appropriate reference ranges for thyroid hormones are required for detecting pediatric thyroid dysfunction. Data on thyroid hormones and peripheral thyroid metabolism in short children born small for gestational age (SGA) before and during GH treatment are lacking.

OBJECTIVES

Our objectives were to obtain pediatric thyroid hormone reference ranges; to investigate thyroid hormones in short SGA children before puberty, during puberty, and during postponement of puberty by GnRH analog; and to evaluate thyroid hormones during GH treatment.

PATIENTS AND DESIGN

In 512 healthy children (225 females; 0-18 yr), free T(4) (FT(4)), TSH, total T(4), T(3), rT(3), and T(4)-binding globulin were determined. Reference ranges were calculated using the linearity, median, and skewness method. In 125 short SGA children (62 females; mean age 11.3 yr), thyroid hormones were analyzed before and after 2 yr of GH treatment and additional GnRH analog.

RESULTS

Thyroid references showed wide ranges postnatally and age-specific patterns thereafter, similar in boys and girls. Untreated short SGA children had similar FT(4) and T(4) levels as the reference population but significantly higher T(3), rT(3), and T(4)-binding globulin levels. During puberty and during GH treatment, FT(4) and rT(3) significantly decreased, whereas T(3) significantly increased.

CONCLUSION

Age-specific thyroid reference ranges are presented. Puberty and GH treatment both induce changes in peripheral thyroid metabolism, resulting in more biologically active T(3) at the expense of less inactive rT(3), possibly mediated by IGF-I. GH treatment induces altered peripheral thyroid metabolism but does not result in thyroid dysfunction.

Autoimmune thyroiditis and diabetes mellitus type 1 after long-term gonadotropin-releasing hormone agonist treatment for central precocious puberty: evolution or coincidence?

Very few abnormalities in endocrine function have been reported during long term gonadotropin-releasing hormone agonist (GnRHa) treatment in girls. Most authors agree that this therapy is safe and effective. We present an unusual outcome of long term GnRHa therapy in two girls with central precocious puberty(CPP) of idiopathic or organic origin. They have received monthly depot injections of triptorelin acetate for a time period of 8 years. Thyroid function was examined by measuring serum levels of thyrotropin (TSH), thyroxine (T4), thyroid antibodies, and ultrasound of the thyroid gland. One of the girls was at the age of 8.5 years, having elevated thyroid antibodies, mild goitier and an abnormal ultrasound of the thyroid gland, suggesting autoimmune thyroiditis. Another girl with a hypothalamic hamartoma developed diabetes mellitus at the age of 9 years. Both of these girls were early diagnosed for CPP, at 6 months and 8 months respectively, and given GnRHa treatment. So far, it is not known whether these autoimmune diseases are related to the GnRHa treatment or are simply a coincidence. However, we suggest a closer monitoring of girls with CPP who have had a long period of treatment.

High growth rate of girls with precocious puberty exposed to estrogenic mycotoxins

OBJECTIVE

To test the hypothesis that human puberty timing can be advanced by environmental estrogen exposure.

STUDY DESIGN

We analyzed serum mycoestrogen contamination via high-performance liquid chromatography (HPLC) in 32 girls affected by central precocious puberty (CPP) and in 31 healthy female control subjects. All 32 patients received triptorelin (TR) for more than 12 months after diagnosis.

RESULTS

Increased serum levels of zearalenone (ZEA; 933.7 +/- 200.3 pg/mL; 95% CI, 723.5-1143.9) and of its congener alpha-zearalenol (106.5 +/- 1.9 pg/mL; 95% CI, 104.5-108.5) contaminated 6 girls with CPP, who were from a bounded Tuscany area. At diagnosis, ZEA levels correlated with patient height (r = 0.906, P < .05) and weight (r = 0.887, P < .05), but not with bone age. In patients who were mycotoxin-positive, height (F = 4.192; P < .01), weight (F = 3.915; P < .01), and height velocity (F = 2.777, P < .05) were higher than patients who were mycotoxin-negative during 12-months TR treatment. Height correlated with weight both in patients who were mycotoxin-positive (r = 0.986, P < .001) and in patients who were mycotoxin-negative (r = 0.994, P < .001). Body mass index, bone age, and gonadal secretion was not different in patient groups before and during TR treatment (P > .05).

CONCLUSIONS

Mycoestrogenic zearalenone is suspected to be a triggering factor for CPP development in girls. Because of its chemical resemblance to some anabolic agents used in animal breeding, ZEA may also represent a growth promoter in exposed patients.