Asli Nar

Metabolic syndrome and its components are associated with increased thyroid volume and nodule prevalence in a mild-to-moderate iodine-deficient area

OBJECTIVE Metabolic syndrome (MetS) is a cluster of metabolic abnormalities with insulin resistance (IR) as a major component. It has been recently questioned whether MetS and its related components are associated with functional and morphological alterations of the thyroid gland. The aim of our study is to examine thyroid volume and nodule prevalence in a case-control study of patients with MetS in a mild-to-moderate iodine-deficient area. DESIGN Two hundred and seventy-eight patients with MetS were randomly matched for age, gender, and smoking habits with 261 subjects without MetS. Serum TSH, free tri-iodothyronine and thyroxine, and the level of IR, which was estimated by the homeostasis model assessment for IR, as well as other MetS parameters were evaluated. Thyroid ultrasonography was performed in all subjects. All subjects with thyroid nodules >1 cm were offered to undergo thyroid fine needle aspiration biopsy. RESULTS TSH was significantly positively correlated with the presence of MetS diagnosis. There was no association between free thyroid hormone levels and MetS and its related components. Mean thyroid volume was significantly higher in patients with MetS than in controls (17.5 + or - 5.5 vs 12.2 + or - 4.2 ml, P<0.0001). Also the percentage of patients with thyroid nodules was significantly higher in patients with MetS (50.4 vs 14.6%, P<0.0001). Subjects were also divided into two groups according to the presence of IR. The group of subjects with IR had increased thyroid volume and nodule formation. The odds ratio for the development of thyroid nodule in the presence of IR was 3.2. TSH as well as all MetS components were found to be independent predictors for thyroid volume increase. IR but not TSH was found to be correlated with thyroid nodule formation. Thyroid cancer was diagnosed in 3 out of 38 patients with MetS who agreed to have a biopsy (7.9%). None of the subjects in the control group was diagnosed to have thyroid cancer. CONCLUSIONS The results suggest that patients with MetS have significantly increased thyroid volume and nodule prevalence. Multivariate regression analysis model demonstrated that the presence of IR contributed substantially to this increased risk. Our data provide the first evidence that IR is an independent risk factor for nodule formation in an iodine-deficient environment.

Effects of bilateral ovariectomy and estrogen replacement therapy on serum leptin, sex hormone binding globulin and insulin like growth factor-I levels

Studies evaluating the effect of estrogen replacement therapy (ERT) on leptin levels are contradictory. The aim of this study was to investigate effects of bilateral ovariectomy and ERT on serum leptin levels and anthropometric measurements as well as interaction among leptin, sex hormone binding globulin (SHBG), and insulin like growth factor-I (IGF-I) in premenopausal women after bilateral ovariectomy. Twenty-four premenopausal women who undergo bilateral overiectomy were divided into two groups based on whether they received hormonal treatment postoperatively. The studied parameters were evaluated in both groups preoperatively and during the fourth and eighth weeks postoperatively. Serum leptin, testosterone, prolactin, insulin, IGF-1 levels, BMI, HOMA-IR, and waist-to-hip ratio values did not change in both groups at all times. In the estradiol group, serum SHBG concentrations were significantly higher on weeks 8 compared with control group and basal values (p = 0.03 and 0.014, respectively). Leptin levels showed a positive linear correlation with BMI in all groups and at all times evaluated (r = 0.80, p < 0.01 for controls and r = 0.62, p < 0.01 for women treated with 17β-estradiol) and with insulin in estradiol group on weeks 4 (r = 0.755, p < 0.05). No correlation was found between leptin and estradiol, testosterone, prolactin, SHBG, IGF-1 levels, and anthropometric variables at all times. Leptin levels do not show modification 8 weeks after bilateral ovariectomy and under ERT, suggesting that estrogens do not have a stimulatory action on leptin in humans. Although needing confirmation by a longer study, our findings suggest that IGF-I system and SHBG did not regulate leptin and vice versa and ERT do not have any effect on leptin, SHBG, and IGF-I.

Isolated adrenocorticotropic hormone deficiency, thyroid autoimmunity, and transient hyperprolactinemia.

OBJECTIVE To describe a case of isolated adrenocorticotropic hormone (ACTH) deficiency associated with thyroid autoimmunity, subclinical hypothyroidism, and transient hyperprolactinemia. METHODS We present a detailed case report, including results of laboratory studies and magnetic resonance imaging, and discuss potential contributing factors in this setting. RESULTS In a 23-year-old woman with isolated ACTH deficiency accompanied by thyroid autoimmunity (Hashimotos thyroiditis), subclinical primary hypothyroidism, and hyperprolactinemia, magnetic resonance imaging of the pituitary showed normal findings but dynamic stimulation testing of the pituitary gland indicated an isolated ACTH deficiency with intact growth hormone and gonadotropin secretory reserves. The cortisol response to the short ACTH stimulation test was subnormal. Therapy with prednisolone (5 mg/day) and levothyroxine (100 microg/day) was initiated. Results of thyroid function tests were normalized after 1 month, the prolactin level decreased to normal after 1 year, and titers of thyroid autoantibodies decreased substantially after 1.5 years of treatment. CONCLUSION The correction of the related glucocorticoid deficiency resulted in resolution of the hyperprolactinemia and a decrease in titers of thyroid autoantibodies.

Thyroid volume in patients with glucose metabolism disorders

OBJECTIVE Thyroid volume and the prevalence of thyroid nodules are higher in patients with insulin resistance. A relationship between thyroid volume and glucose metabolism disorders (GMD) has not as yet been clarified. The present retrospective study aimed to investigate the association between GMD and thyroid volume. SUBJECTS AND METHODS We investigated the data of 2,630 patients who were evaluated for thyroid biopsy in our hospital. The study population included 602 patients with GMD, 554 patients with diabetes mellitus (DM) and 1,474 patients with normal glucose metabolism as a control group. We obtained the levels of serum thyroid stimulating hormone (TSH) and the thyroid volumes of those patients retrospectively. RESULTS The median ages for the control group, GMD group and DM group were 55 (15-91) years, 60 (27-97) years, and 65 (27-91) years respectively and there was a statistically significant difference between the groups with regard to age and gender (p<0.001). Levels of TSH were similar in all groups. The median total thyroid volumes for patients with DM and GMD were significantly higher than that of the control group [22.5 (3-202) mL, 20.2 (4-190) mL, and 19.2 (3-168) mL respectively, p≤0.001 for all parameters]. Also the median total thyroid volume for patients with DM was significantly higher than that of the GMD group (p<0.001). According to the correlation analysis, thyroid volume was significantly correlated with age (r=0.92, p<0.001) and TSH (r=0.435, p<0.001). Age, gender, TSH levels, GMD and DM diagnosis were independently correlated with thyroid volume. CONCLUSION The thyroid gland is one of the target tissues of metabolic disorders. We reported a positive correlation between GMD/type 2 DM and thyroid volume. Further controlled, prospective, randomized studies on this subject are required to gain more information.

Do Statins Affect Thyroid Volume and Nodule Size in Patients with Hyperlipidemia in a Region with Mild-to-Moderate Iodine Deficiency? A Prospective Study

Objective: The objective of this study was to assess the antiproliferative pleiotropic effects of statins on thyroid function, volume, and nodularity. Subjects and Methods: One hundred and six hyperlipidemic patients were included in this prospective study. The 69 patients in the statin groups received atorvastatin (16 received 10 mg and 18 received 20 mg) or rosuvastatin (20 received 10 mg and 15 received 20 mg). The 37 patients in the control group, assessed as not requiring drugs, made only lifestyle changes. Upon admission and after 6 months, all patients were evaluated by ultrasonography as well as for lipid variables (total cholesterol, high- and low-density lipoprotein cholesterol, and triglycerides) and thyroid function and structure. Results: After 6 months, no differences in thyroid function, thyroid volume, the number of thyroid nodules, or nodule size were observed in the statin and control groups. In a subgroup analysis, total thyroid volume had decreased more in patients receiving 20 mg of rosuvastatin than that in the control group (p < 0.05). Maximum nodule size had decreased more in those receiving 10 mg of rosuvastatin (p < 0.05). Conclusions: Our results suggest an association between rosuvastatin treatment and smaller thyroid volume and maximum nodule diameter; this could be attributable to the antiproliferative effects of statin therapy on the thyroid.