Hyperthyroidism: multiple possibilities in the female patient.

Hyperthyroidism is a clinical syndrome characterized by an excess of thyroid hormone, and its clinical consequences. A suppressed serum TSH concentration is the earliest biochemical manifestation of hyperthyroidism. Subclinical hyperthyroidism, characterized by suppressed serum TSH concentration alone, has important clinical consequences. These include bone loss in postmenopausal women and atrial fibrillation. A twenty-four hour radioiodine uptake and radionuclide scan are indispensable in the differential diagnosis of hyperthyroidism. Graves' Disease, an autoimmune disorder, demonstrates a strong female prevalence; the twenty-four hour radioiodine uptake is normal or elevated. Therapeutic options, including anti-thyroid drugs, radioactive iodine (131I) and surgery are utilized in all age groups. These include use in women during the reproductive years. Toxic nodular goiter and "hot" nodules are less common forms of hyperthyroidism; these too have normal or elevated radioiodine uptake, with characteristic radionuclide scans. Hyperthyroidism with a near-zero radioiodine uptake also has important clinical implications. Factitious (exogenous) hyperthyroidism is characterized by a low serum thyroglobulin concentration. Treatment consists of decreasing the dosage of, or withdrawing, thyroid hormone. Painful subacute thyroiditis, a post-vital syndrome, causes spontaneously resolving hyperthyroidism, which is often followed by hypothyroidism. The most common cause of hyperthyroidism with a low radioiodine uptake is painless, lymphocytic subacute thyroiditis. Here too, hyperthyroidism spontaneously resolves and often passes through a hypothyroid phase. This phase often requires therapy, and permanent mild or severe hypothyroidism may result.