Differences in levothyroxine action on thyroid autoimmunity and hypothalamic-pituitary-thyroid axis activity between metformin- and myo-inositol-treated women with autoimmune subclinical hypothyroidism

WHAT IS KNOWN AND OBJECTIVE

Insulin resistance impairs the impact of levothyroxine on thyroid autoimmunity and hypothalamic-pituitary-thyroid axis activity. Both metformin and myo-inositol were found to improve insulin sensitivity and to reduce thyrotropin levels in individuals with hypothyroidism. The aim of the present study was to compare the effect of levothyroxine on thyroid autoimmunity and hypothalamic-pituitary-thyroid axis activity between women receiving metformin and myo-inositol.

METHODS

The study included two groups of women with autoimmune hypothyroidism, treated for at least 6 months with either metformin (group A; n = 25) or myo-inositol (group B; n = 25). Both groups were matched for age, insulin sensitivity, hormone levels and antibody titers. For the following 6 months, all women received levothyroxine. Plasma levels of glucose, insulin, thyrotropin, free thyroid hormones, prolactin, 25-hydroxyvitamin D and high-sensitivity C-reactive protein (hsCRP), as well as titers of thyroid peroxidase and thyroglobulin antibodies were assessed at the beginning and at the end of the study.

RESULTS AND DISCUSSION

At baseline there were not differences between the study groups. Although levothyroxine reduced thyrotropin levels, increased free thyroid hormone levels and decreased antibody titers in both study groups, these effects were more pronounced in group A than group B. Only in group A, levothyroxine increased 25-hydroxyvitamin D, decreased hsCRP and improved insulin sensitivity. The impact of levothyroxine on thyrotropin and free thyroid hormones correlated with treatment-induced changes in insulin sensitivity, antibody titers, 25-hydroxyvitamin D and hsCRP.

WHAT IS NEW AND CONCLUSION

The present study suggests that the impact of levothyroxine on thyroid autoimmunity and hypothalamic-pituitary-thyroid axis activity is stronger in women receiving metformin than in women treated with myo-inositol.

Current and experimental drug therapy for the treatment of polycystic ovarian syndrome

INTRODUCTION

Polycystic ovary syndrome (PCOS) is an endocrine disorder that affects 8-13% of reproductive-age women. Irregular periods, hirsutism, or infertility are the most common clinical presentations of patients affected by PCOS. This syndrome is also linked to metabolic abnormalities such as type 2 diabetes, insulin resistance and obesity. The optimal therapeutic approach is still unknown.

AREAS COVERED

This narrative review offers an overview of the literature on current and experimental pharmacological options for treating PCOS and highlights ongoing clinical trials. Several electronic databases were searched and current research registers were analyzed to the present year. The papers selected for this review were critically analyzed, and all data available were summarized, organized, and explored to derive key information.

EXPERT OPINION

The main goal of PCOS treatment is to obtain a metabolic and hormonal balance. Optimal PCOS therapy should be direct to the reproductive abnormalities and the entire spectrum of endocrine and metabolic complications that appear to have a long-term negative impact on PCOS patient health, as in post-menopausal period. The discovery of new mechanisms in PCOS pathogenesis will offer the possibility of testing new drug classes.

Diabetic Pharmacotherapy and Endometrial Cancer Risk Within a Publicly Funded Health Care System

OBJECTIVE

There is conflicting evidence regarding the association between metformin and endometrial cancer risk. The objective of this study was to evaluate the association between type of diabetic pharmacotherapy and endometrial cancer risk within a population-based study. The hypothesis was that metformin was associated with the lowest risk.

METHODS

This was a nested case-control study using data from the BC Cancer Registry (2000-2009) and from a province-wide prescription network (PharmaNet) since 1996. Patients were classified by drug exposure (metformin, thiazolidinediones, secretagogues, with or without insulin). The primary analysis was a conditional logistic regression to estimate the odds ratios for endometrial cancer in the drug exposure groups. Sensitivity analysis was carried out to account for uncertainty regarding various parameters. The secondary analysis evaluated the effect of dosage using a principal components analysis.

RESULTS

The study cohort comprised 492 cases and 4404 controls. The primary analysis revealed no difference in endometrial cancer risk between those using metformin and those prescribed other classes of medications (OR 1.5, 95% CI 0.9 to 2.4). Women receiving all classes of medications had almost a two-fold increase in risk (OR 1.9, 95% CI 1.1 to 3.3). The secondary analysis revealed an increased risk associated with a greater duration of treatment and number of prescriptions (OR 1.3, 95% CI 1.2 to 1.4).

CONCLUSION

In this population-based study, metformin was not associated with a decreased endometrial cancer risk. Women receiving multiple types of medications over a long time had the highest risk, implying that the extent of insulin resistance, rather than the effect of any specific medication, drives endometrial cancer risk.