Thyroid Diseases: Planet Earth

Koutkia P, Mylonakis E, Levin RM. · Section of Endocrinology, Diabetes and Nutrition, Boston University Medical Center, Boston, Massachusetts 02118, USA. · Thyroid. · Pubmed #12193301 No free full text.

Abstract: Abnormalities of thyroid function are associated with a number of systemic conditions, including patients infected with human immunodeficiency virus (HIV). Most patients with early HIV infection and a stable body weight have normal thyroid function. Subtle abnormalities of a number of thyroid function tests have been reported during the early asymptomatic phase of HIV disease. These include an inappropriately normal triiodothyronine (T(3)) and reduced reverse triiodothyronine (rT(3)), and increased thyroxine-binding globulin (TBG) levels. Opportunistic infections involving the thyroid gland, neoplasms such as lymphoma and Kaposi's sarcoma, and medications can alter the thyroid function in individuals with more advanced HIV infection. If thyroid dysfunction is diagnosed in an HIV-infected patient, it should be treated in the usual manner. However, high index of suspicion and caution in the interpretation of thyroid function tests in patients with HIV disease are needed for optimal diagnosis and treatment.

Rao AS, Kremenevskaja N, von Wasielewski R, Jakubcakova V, Kant S, Resch J, Brabant G. · Department of Gastroenterology, Hepatology, and Endocrinology, D-30625 Hannover, Germany. · J Clin Endocrinol Metab. · Pubmed #16263821 links to  free full text

Abstract: CONTEXT: Dysregulation of Wnt signaling is a key step in neoplastic thyrocyte proliferation. However, it is unclear whether the selective tyrosine kinase (TK) inhibitor, imatinib mesylate, is linked to the Wnt/beta-catenin cascade and is able to modulate the pathway. OBJECTIVE: Conflicting data are reported on the therapeutic effects of imatinib in anaplastic thyroid carcinomas (ATCs), but the molecular mechanism of action is unclear. Here, we further delineated the antitumor effects and the potential efficacy of imatinib in dedifferentiated thyroid carcinomas. RESULTS: Tissue microarray of histologically proven ATCs (n = 12) demonstrated that six of 12 tumors expressed at least one of the imatinib-sensitive TKs. Similarily, imatinib-sensitive TKs were detected in seven of 10 thyroid cancer cell lines derived from metastatic papillary, follicular, and ATCs. Coimmunoprecipitation in ARO cells demonstrated a direct link between c-abl and beta-catenin. Imatinib (10 microM for 48 h) drastically reduced beta-catenin expression and redistributed it from the nucleus to the cell membrane. It stabilized adherens junctions by increasing beta-catenin/E-cadherin binding and reduced the invasive potential of thyroid cancer. Furthermore, imatinib (10 microM for 48 h) attenuated T cell factor/lymphoid enhancer factor activity, reduced cyclin D1 levels and dose-dependently suppressed thyrocyte proliferation by half without affecting apoptosis. CONCLUSION: Our data provide a molecular mechanism for the antitumor activity of imatinib that may help to develop it as a therapeutic option in a subset of ATC patients.

Bastemir M, Emral R, Erdogan G, Gullu S. · Ankara University, School of Medicine, Department of Endocrinology and Metabolic Diseases, Ankara, Turkey. · Thyroid. · Pubmed #17199437 No free full text.

Abstract: In the present study we evaluated the effects of iodine intake on the prevalence of thyroid dysfunction, autoimmunity, and goiter in two regions with different iodine status after two years of iodization in Turkey. In total 1733 adolescent subjects were enrolled into the study (993 from an iodine-sufficient area--the Eastern Black Sea Region (group 1) and 740 from an iodine-deficient area--Middle Anatolia (group 2)). We measured free thyroxine (FT(4)), thyrotropin (TSH), antithyroid peroxidase antibodies (Anti-TPO), antithyroglobulin antibodies (Anti-Tg), and urinary iodine (UI), and examined the thyroid gland by ultrasound. Median urinary iodine excretion was found to be significantly different in group 1 and group 2 (139 micro/l vs 61micro/l, p < 0.001). Hyperthyroidism was more frequent in group 1 (3.6% vs 0.7%; p < 0.001), but the hypothyroidism rate was similar between groups (1.8% vs 1.4 %; p>0.05). The percentage of anti-Tg positive subjects was found to be 17.6% in group 1 and 6.4% in group 2; that of anti-TPO positive subjects was 4.3% in group 1 and 1.5% in group 2. The prevalence of antithyroid antibody (anti-Tg and/or anti-TPO) positivity was significantly higher in group 1 than in group 2 (18.52% vs 6.62%; p < 0.001). Thyroid volumes of the hyperthyroid subjects in both groups were significantly higher than hypo- and euthyroid subjects. In conclusion, iodine supplementation in Turkey has resulted in the elimination of iodine deficiency in the Eastern Black Sea Region, and this has been accompanied by an increase in the prevalence of autoimmune thyroiditis and thyroid dysfunction.