Endocrine disorders thyroid gland

Myopathy is the term used broadly for affections of the skeletal musculature, in which the muscular symptoms in no way arise from disordered function of the central or peripheral nervous system. Within this definition are included, therefore, such widely differing conditions as the polymyositis syndrome, endocrine myopathies associated with thyroid gland disorders, and the muscular dystrophies. 

This chapter gives a general overview of the endocrine system. Some detail is given of the thyroid gland, the adrenal glands, the pancreas and disorders of them because health care professionals are likely to come across patients with such disorders. 

Endocrine In patients receiving the minimum dose of amiodarone, thyroid abnormalities were observed at a rate between 14% and 18%. The effects on the thyroid gland are variable. Amiodarone may cause abnormal thyroid function detected only by laboratory test as well as clinically manifested thyroid dysfunction. The mechanism of this adverse effect is complex. Amiodarone inhibits the action of deiodinase and decreases peripheral conversion of thyroid hormones. Moreover, it decreases their renal elimination and inhibits their entry to peripheral tissues. The level of T4 increases by 40% within 1-4 months of amiodarone therapy. The deiodinase activity inhibition can be noticed after 3 months of treatment. It leads to an increase in the level of thyroid stimulating hormones. Amiodarone and its metabolite have a direct cytotoxic effect on thyroid follicular cells, which results in destructive thyroiditis. Amiodarone-induced thyroid damage can lead either to hypo- or hyperthyroidism. The latter can be of two types. Type 1 usually occurs in patients with prior thyroid damage. In this type, iodine excess causes excessive synthesis of thyroid hormones whereas in type 2 the inflammatory process is followed by destruction. A destructive thyroiditis leads to the release of hormones from damaged thyroid follicular cells. This mechanism occurs in patients with no history of thyroid disorders [15]. 

Mulliplc endocrine neoplasias are inherited disorders. The syndromes are usually transmitted in an autosomal dominant pattern. The endocrine glands most often affected are the parathyroid, pituitary, pancreas, thyroid and adrenal. It is postulated that the cell types involved in these tumours have a common embryological precursor. There arc three well-dcrmed multiple endocrine neoplasia syndromes (Fig. 2). 

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