Vclinical Considerations

A. Graves disease is hyperthyroidism caused by a diffuse, hyperplastic goiter.

1. It is relatively common in women.

2. It is an autoimmune disease that produces TSH receptor-stimulating autoantibodies.

3. It is characterized clinically by ophthalmopathy (lid stare, eye bulging), heat intolerance, nervousness, irritability, and weight loss in the presence of a good appetite.

B. Secondary hyperthyroidism is relatively uncommon and may be caused by a TSH adenoma in the adenohypophysis.

C. Hashimoto thyroiditis is the most common cause of goitrous hypothyroidism.

1. It is relatively common in middle-aged women.

2. It is an autoimmune disease that produces thyroid peroxidase autoantibodies.

3. It is characterized clinically by goiter and hypothyroidism. In some variants of Hashimoto thyroiditis, only hypothyroidism and no goiter exists.

D. Primary hypothyroidism

1. Primary hypothyroidism is most commonly idiopathic, whereby TSH receptor-blocking autoantibodies are present.

2. It is characterized clinically by low blood pressure, low heart rate, low respiratory rate, reduced body temperature, and myxedema (peripheral nonpitting edema).

E. Secondary hypothyroidism is relatively uncommon and caused by a deficiency in the adenohypophysis (low TSH secretion) or hypothalamus flow thyrotropin-releasing factor (TRF) secretion].

F. Estrogen effect. The use of oral contraceptive pills or the use of diethylstilbestrol for treatment of prostatic cancer increases synthesis of TRG.

G. Diffuse nontoxic (simple) goiter is an enlargement of the entire thyroid gland in a diffuse manner without producing nodules.

1. It occurs most commonly in particular geographic areas (called endemic goiter), most often caused by deficiency of iodine in the diet.

2. Wherever endemic goiter is prevalent, endemic cretinism occurs. A severe iodine deficiency during fetal development results in growth retardation and severe mental retardation.

H. Diagnosis. Table 21-1 shows the laboratory findings used for diagnosis.

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