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  • Sweating, weight loss or gain, anxiety, palpitations, loose stools, heat intolerance, menstrual irregularity.

  • Tachycardia; warm, moist skin; stare; tremor.

  • Graves disease is most common cause of hyperthyroidism; palpable goiter (sometimes with bruit) seen in most patients; ophthalmopathy also common.

  • Suppressed TSH in primary hyperthyroidism; usually increased T4, FT4, T3, FT3.


The term “thyrotoxicosis” refers to the clinical manifestations associated with elevated serum levels of T4 or T3 that are excessive for the individual (hyperthyroidism). Serum TSH levels are suppressed in primary hyperthyroidism. However, certain drugs and conditions can affect laboratory tests and lead to the erroneous diagnosis of hyperthyroidism in euthyroid individuals (Table 26–4). The causes of hyperthyroidism are many and diverse, as described below.

Table 26–4.Factors that can cause aberrations in laboratory tests that may be mistaken for spontaneous clinical primary hyperthyroidism.1

A. Graves Disease

Graves disease (known as Basedow disease in Europe) is the most common cause of thyrotoxicosis. It is an autoimmune disorder affecting the thyroid gland, characterized by an increase in synthesis and release of thyroid hormones (eFigure 26–7); autoantibodies known as thyroid-stimulating immunoglobulins (TSI) or TSH receptor antibodies bind to the TSH receptor in thyroid cell membranes and stimulate the gland to hyperfunction.

eFigure 26–7.

Graves disease. (Used, with permission, from P Forsham, MD.)

Graves disease is much more common in women than in men (8:1), and its onset is usually between the ages of 20 and 40 years. It may be accompanied by infiltrative ophthalmopathy (Graves exophthalmos) and, less commonly, by infiltrative dermopathy (pretibial ...

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