Hypothyroidism is the most common disorder of thyroid function. It is usually due to some disorder of the thyroid gland, which results in reduced production & secretion of thyroid hormones resulting in reduced supply of active thyroid hormones to peripheral tissues. It is accompanied by increased TSH amounts (primary hypothyroidism) by the known mechanism of retrograde regulation.
Much less often, hypothyroidism results from reduced secretion of TSH and thus reduced stimulation of the thyroid to produce and secrete thyroid hormones (secondary or central hypothyroidism). Secondary hypothyroidism can be due to either a pituitary or hypothalamic disorder. In the latter there is reduced TRH secretion. Usually the value of TSH is low or "unsuitably" normal for the corresponding low values of thyroid hormones.
|Etiology of hypothyroidism|
|Destruction of thyroid tissue|
|Chronic autoimmune thyroiditis – (atrophic form or with goitre)|
|131I (treatment of hyperthyroidism)|
|Ext. Cervical radiation (lymphoma, etc.)|
|Subtotal or total thyroidectomy|
|Antithyroid drugs (lithium, amiodarone iodine)|
|Hypothalamus – pituitary diseases|
|Transient primary hypothyroidism|
|Post partum thyroiditis|
|Symptoms and clinical findings of hypothyroidism|
|Cold intolerance||Slow reflexes|
GRADUATE COURSES IN ENDOCRINOLOGY AND DIABETES- DEPARTMENT OF ENDOCRINOLOGY DIABETES AND METABOLISM OF EVANGELISMOS GENERAL HOSPITAL OF ATHENS- 2004