Results of oral TRH test in the differentiation of compensated and decompensated autonomous thyroid nodules

In 17 patients with compensated autonomous adenomas of the thyroid, iv thyrotropin releasing hormone (TRH) tests (200 microgram) and oral TRH tests (40 mg) were performed. In nine of these patients, thyroid-stimulating hormone (TSH) 30 min after iv TRH showed a normal (greater than 2.7 microU/ml) and in eight patients a subnormal (less than 2.7 microU/ml) or negative response. However, after prolonged oral stimulation with 40 mg TRH, after 120-180 min TSH was normal (greater than 2.7 microU/ml) in 15 and subnormal (less than 2.7 microU/ml) in two patients. In 20 patients with decompensated autonomous thyroid nodules. TSH was not detectable (less than 0.8 microU/ml) after iv or oral TRH stimulation. Therefore, the oral TRH stimulation test seemed to be superior to the iv TRH test in the discrimination of compensated and decompensated autonomous adenomas of the thyroid.