The clinical presentation of overt thyrotoxicosis can be subtle and nonspecific. Some patients may complain of classic symptoms such as nervousness, sweating, fatigue, heat intolerance, weakness, tremor, hyperactivity, changes in weight or appetite, insomnia, exertional dyspnea, hyperdefecation, or palpitations. Oligomenorrhea occurs in about one in four women with thyrotoxicosis (25). Thyrotoxic patients, especially among the elderly, may have higher rates of depression than their euthyroid counterparts (26). Although subclinical thyrotoxicosis is usually assumed to be asymptomatic, some studies suggest it may be possible to elicit subtle physical and psychiatric symptoms in these patients (27).
Physical findings in thyrotoxicosis may include hyperactivity, tachycardia or atrial fibrillation, systolic hypertension, warm, moist, smooth skin, stare and eyelid retraction, tremor, hyperreflexia, and muscle weakness (28). Goiter is not invariably present: one study found that 37% of thyrotoxic patients over age 60 did not have thyroid enlargement (29). In Graves' disease, ophthalmologic findings may include exopthalmos, extraocular muscle dysfunction, periorbital edema, conjunctival chemosis and injection, and exposure keratitis (30). Pretibial myxedema is rarely seen in patients with Graves' disease and only when eye disease is also present.
After the fifth decade of life, there is a gradual decrease in the number of classic presenting signs and symptoms of thyrotoxicosis (31-33). Even overt thyrotoxicosis may go undiagnosed in older patients in the absence of routine TSH screening. Rather than appearing hyperactive as younger patients do, older individuals with thyrotoxicosis may seem placid or depressed, i.e., the "apathetic hyperthyroidism" described by Lahey in 1931 (34). Although older patients with hyperthyroidism are less likely than younger ones to have a resting tachycardia, they are more likely to have atrial arrhythmia (35). Weight loss in younger patients is usually associated with increased appetite, whereas in older patients it may instead be associated with anorexia (36).
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