The diagnosis of hyperthyroidism is usually evident in patients with unequivocal clinical and biochemical manifestations of the disease. Other patients have fewer and less obvious clinical signs, but definite biochemical hyperthyroidism. Still others have little or no clinical hyperthyroidism and their only biochemical abnormality is a low serum thyrotropin (TSH) concentration, a disorder called subclinical hyperthyroidism.
Following a brief discussion of the clinical manifestations of hyperthyroidism, the diagnosis and evaluation of patients with hyperthyroidism will be presented here. An overview of the clinical manifestations of hyperthyroidism, disorders that cause hyperthyroidism, the diagnosis of hyperthyroidism during pregnancy, and subclinical hyperthyroidism are discussed in detail separately. (See "Overview of the clinical manifestations of hyperthyroidism in adults" and "Disorders that cause hyperthyroidism" and "Hyperthyroidism during pregnancy: Clinical manifestations, diagnosis, and causes" and "Subclinical hyperthyroidism".)
Overt hyperthyroidism — Most patients with overt hyperthyroidism have a dramatic constellation of symptoms. These symptoms characteristically include anxiety, emotional lability, weakness, tremor, palpitations, heat intolerance, increased perspiration, and weight loss despite a normal or increased appetite [1,2].
While the combination of weight loss and increased appetite is a characteristic finding, some patients gain weight, in particular younger patients, due to excessive appetite stimulation . Other symptoms that may be present include hyperdefecation (not diarrhea), urinary frequency, oligomenorrhea or amenorrhea in women, and gynecomastia and erectile dysfunction in men [3,4]. (See "Overview of the clinical manifestations of hyperthyroidism in adults".)
Milder symptoms — Patients with mild hyperthyroidism and older patients often have symptoms that are referable to one or only a few organ systems . Isolated symptoms and signs that should lead to evaluation for hyperthyroidism in patients of any age include unexplained weight loss, new onset atrial fibrillation, myopathy, menstrual disorders, and gynecomastia.