Hyperthyroidism in Graves disease. Current trends in management and diagnosis.

The radioimmunoassay for T3 is now widely available and is a useful diagnostic tool for hyperthyroidism, especially in T3-thyrotoxicosis. It is an essential tool in the management of hyperthyroidism that persists after treatment with normal T4 serum levels or, in euthyroid cases, with low T4 serum levels. In these conditions, it reflects the metabolic state more accurately than serum levels of T4. A promising new test is the response of radioimmunoassayable TSH to protirelin (TRH) administration. An absent response indicates pituitary suppression and thyroid autonomy as seen in frank hyperthyroidism or euthyroid Graves disease, treated or untreated. It is safer and quicker than the conventional T3 suppression test of thyroid radioactive iodine uptake and may replace it at least partly in the future.