Is it hyperthyroidism? You can't always tell from the clinical picture.

Hyperthyroidism usually causes a typical clinical syndrome in younger patients, but in some cases it presents with only minimal or atypical symptoms. This is especially true in older patients, who may have none of the typical signs, such as goiter. Differentiation between a euthyroid hyperthyroxinemic state and hyperthyroidism is crucial to avoid unnecessary treatment of persons with a normally functioning thyroid gland. In addition, distinguishing between causes of hyperthyroidism is important, because the treatments may be completely different. For example, in subacute thyroiditis, supportive care and observation are usually the only treatments needed, whereas in Graves' disease or toxic multinodular goiter, more definitive therapy is required.