Disorders of the Thyroid Gland

Disorders related to thyroid gland - a. Hyperthyroidism : Hyperthyroidism, caused by raised levels of thyroid hormone, drives up overall metabolic rate and body temperature, producing sweating, hot flushes, rapid respiration and heightened nervous sensitivity, along with bulging eyeballs and disruption of other physiological activities. In adults this picture, together with protruding eyeballs, increased basal metabolic rate and weight loss, is specifically named Grave's disease (exophthalmic goitre); the raised BMR additionally produces a faster heartbeat, higher blood pressure, higher body temperature, nervousness, irritability and finger tremor. (The book's Fig. 9.29 is a photograph of such bulging eyeballs.)

b. Hypothyroidism : Hypothyroidism is caused by thyroid hormone deficiency or removal of the thyroid gland (thyroidectomy). In infants, hyposecretion causes cretinism -- reduced BMR and oxidation, short stature from a skeleton that fails to grow properly, mental retardation, dry skin, a thick tongue, prolonged neonatal jaundice, lethargy and constipation, though it can be treated by early administration of thyroid hormone. In adults, thyroid hormone deficiency instead causes myxoedema -- characterised by peculiar thickening and puffiness of the skin and subcutaneous tissue (especially of the face and extremities), lack of alertness and intelligence, slow heart rate, low blood pressure, low body temperature and retarded sexual development; hypothyroidism during pregnancy specifically causes defective development and maturation of the growing baby. …