Many people assume that the only serious negative effects of smoking are on the lungs.
However, this study of 132 pairs of twins (264 subjects) showed that smoking can have negative effects on the endocrine system as well, causing a 3 to 5 fold increase in the risk of all types of thyroid disease. The association was most pronounced in autoimmune disorders (Graves' disease and autoimmune thyroiditis), although there was still a strong association for non-autoimmune thyroid disorders.
Located in the front of the neck just below the larynx, the thyroid gland is an important endocrine organ. It secretes the hormones thyroxine (T4), triiodothyronine (T3), and calcitonin , which control body metabolism and regulate calcium balance. The thyroid hormones T1 and T2 are produced as well, although their physiologic effects and importance are unknown and they are largely considered inactive and useless substances.
Graves' disease and autoimmune thyroiditis (a.k.a., Hashimoto's Disease) are autoimmune disorders which result in hyperthyroidism and hypothyroidism, respectively.
Archives of Internal Medicine 2000; 160: 661-666.
Just one more reason to not smoke.
If you are intersted in more information on thyroid function, diagnosis of disorders, and treatment, I have recently revised my Thyroid articles, one for diagnosis and another for treatment. Also, I just completed an interview with Mary Shomon, the thyroid guide from about.com.
Mary has one of the best books written on the subject of hypothyroidism. It was just completed a few months ago and if you have or suspect thyroid dysfunction, I would strongly recommend it.
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