The Thyroid Gland is Another Victim of the Insulin Resistance Syndrome
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- Category: Vol. 80, March 2012
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The Thyroid Gland is Another Victim of the Insulin Resistance Syndrome,EBTESSAM ZAKARIA, NASHWA S. GHANEM, RANDA F. ABD AL-SALAM and AMAL R. ELSHEHABY
Abstract
Background: Insulin resistance syndrome is a cluster of risk factors including increased blood pressure, abdominal obesity, lipid abnormalities, and impaired glucose metabolism. Insulin is a thyroid growth factor that stimulates proliferation of thyroid cells in culture. It has been observed that insulin receptors are over expressed in most thyroid tumors as an early step in thyroid carcinogenesis. In order to evaluate the effects of insulin resistance (IR) on the thyroid gland, we developed across-sectional study in euthyroid women.
Methods: Eighty women (mean age 36.85±4.71 years) were evaluated by a thyroid ultrasound (US), fasting plasma insulin and HOMA IR. Subjects were divided into four groups as follows: G1 (n : 24), subjects with IR and obesity; G2 (n : 20), subjects with obesity without IR; G3 (n : 16), subjects with IR and normal weight; and G4 (n : 20) control group (without IR and obesity).
Results: The thyroid volume (TV), measured by US, showed the following values: G1, 17.15±1.6mL; G2, 7.4±1.4mL; G3, 16.53±1.9mL; and G4, 6.07±0.95mL. There was no significant difference in TV between G1 and G3, but differences between G1 and G2, and between G3 and G4 were significant at p<0.05. The percentage of nodular thyroid glands observed by US in each group was as follows: G1, 58%; G2, 15%; G3, 50%; G4, 5%. Again, the differences between G1 and G2 and between G3 and G4 were statistically significant (p<0.005 and p<0.001, respectively, for each comparison). Our study also showed that the greater waist circumference, the greater thyroid volume and the higher incidence of thyroid nodules.
Conclusions: It is concluded that the higher circulating levels of insulin cause increased thyroid proliferation. The clinical manifestations are the larger thyroid volume and the formation of nodules. Thus, the thyroid gland appears to be another victim of the insulin resistance syndrome.