hormonal and metabolic disorders
Hypothyroidism
Introduction
Hypothyroidism is underactivity of the thyroid gland that leads to inadequate production of thyroid hormones and a slowing of vital body functions. Facial expressions become dull, the voice is hoarse, speech is slow, eyelids droop, and the eyes and face become puffy. Usually only one blood test is needed to confirm the diagnosis. Most people with hypothyroidism need to take thyroid hormone for the rest of their life. The thyroid gland secretes thyroid hormones, which control the speed at which the body’s chemical functions proceed (metabolic rate). Thyroid hormones affect many vital body functions, such as the heart rate, the rate at which calories are burned, skin maintenance, growth, heat production, fertility, and digestion. There are two thyroid hormones: T4: Thyroxine (also called tetraiodothyronine) T3:Triiodothyronine The pituitary gland produces thyroid-stimulating hormone (TSH), which stimulates the thyroid gland to produce thyroid hormones. The pituitary gland slows or speeds the release of TSH, depending on whether the levels of thyroid hormones circulating in the blood are getting too high or too low. (See also Overview of the Thyroid Gland .) Hypothyroidism is common, especially among older people, particularly women. It affects about 10% of older women. It can, however, occur at any age. Myxedema is the name given to very severe hypothyroidism. 