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Clinical manifestation

Alteration in thyroid function An alteration in thyroid function can represent either a hypo functional or hyper functional state. The manifestations of these two altered states are summarized below. Table 6.1 Manifestations of hypothyroid and hyperthyroid states Pathophysiology 170 Level of organization Hypo state Hyper state Basal metabolic rate Decreased Increased Sensitivity to catecholamines Decreased Increased General features Myxedematous feutures keep voice impaired growth (child Exophthalmos lid lag decreased blinking Blood cholesterol levels general behavior Increased mental retardation (Infant) Mental & physical sluggishness somnolence Restlessness, irritability anxiety hyperkinesis wakefulness Cardiovascular function Decreased cardiac output Brady cardia Increased cardiac out put tachycardia and palpitations Gastro intestinal function Constipation decreased appetite Diarrhea increased appetite Respiratory function Hypoventilation Dyspnea Muscle tone and reflexes Decreased Increased, with t r e m o r a n d fibrillatory twitching Temperature tolerance Cold intolerance Heat intolerance Pathophysiology 171 Skin and hair D e c r e a s e d sweating coarse and dry skin and hair Increased sweating thin and silky skin and hair Weight Gain Loss Disorders of the thyroid may represent a congential defect in thyroid development or they may develop later in life, with a gradual or a sudden on set. Goiter is an increase in the size of the thyroid gland. It can occur in hypothyroid, euthyroid, and hyperthyroid states. Goiters may be diffuse, involving the entire gland without evidence or nodularity, or they may contain nodules. Diffuse goiters usually become nodular. Goiters may be toxic, producing sings of extreme hyperthyroidism, or thyrotoxicosis, or they may be notoxic. Diffuse nontoxic and multinodular goiters are the result of compensatory hypertophy and hyperplasia of follicular epithelium secondary to some derangement that impaires thyroid hormone output. The degree of thyroid enlargement is usually proportional to the extent and duration of thyroid deficiency. The increased thyroid mass usually achieves a normal, or euthyroid, state eventually. Multinodular goiters produce the largest thyroid enlargements and are often associated with thyrotoxicosis.