Graves’ disease with an auto nomously functioning thyroid nodule

nomously functioning thyroid nodule 505 InTROduCTIOn Diagnostic procedures for thyroid disorder include bio chemical evaluation: measurement of serum thyrotropin (TSH), free thyroid hormone (free thyroxine [FT4], free triiodothyronine [FT3]) and thyroid antibody levels, as well as imaging including ultrasonography (USG) and thyroid scan. In some cases fine needle aspiration bio psy (FNAB) should be performed. These procedures usually allow to reach a definite diagnosis. TSH secretion is regulated primarily by thyroid hormone negative feedback, especially by FT3. Its low levels enhance and high levels suppress TSH secretion, as occurs in hypothyroidism and hyperthyroidism, respectively. Apart from hormone tests, the antithyroid antibody assay is also important in the diagnosis of thyroid disorders. Human thyrotropin receptor antibodies (TRAb) are known causative factors of hyperthyroidism in Graves’ disease. Thyrotropin receptor antibody assay is useful in differential diagnosis, particularly in uncertain cases. There are two types of antibodies directed against TSH receptor, i.e. thyroid stimulating immunoglobulins (TSI), which stimulate thyroid cell and hormone production, and thyroid blocking antibodies (TBAb). Hyperthyroidism is associated with high TSI levels. In patients with both types of antibodies, the thyroid disorder is characterized by high variability, with periods of hypothyroidism, hyperthyroidism and euthyroid state.1 USG, which is the primary procedure for evaluating the volume and structure of the thyroid gland, enables to identify thyroid nodules and suspect auto immune process. Increased blood flow in power Doppler ultrasound confirms Graves’ disease as the cause of hyperthyroidism. Radioisotope imaging of the thyroid gland (thyroid scan) is performed mainly in patients with thyroid cancer, to evaluate iodine-131 (131I) uptake or to detect an auto nomously functioning thyroid nodule prior to 131I treatment of hyperthyroidism.1 Graves’ disease is the most common cause of primary hyperthyroidism (50–80% of hyperthyroid patients). The incidence of Graves’ disease depends on iodine uptake in the study population. Typical symptoms, associated with auto immune mechanisms, include exophthalmos, thyroid bruit and pretibial myxedema. Thyroid scan of Graves’ patients shows an equal radioisotope uptake in both lobes. Patients with new-onset disease receive pharmaco logical treatment. In the case of side effects or recurrence of hyperthyroidism, radioactive iodine or subtotal thyroidectomy are performed.1,2 CASE REPORT