Figure 2. Iodide perchlorate discharge test in two patients with an autonomously functioning thyroid nodule.

Iodide perchlorate test was used to evaluate organification defect in patients with an autonomously functioning thyroid nodule (AFTN). A time 0, 26MBq ¹²³I was administered orally with 500 µg stable iodide. Three hours later, a first scintigraphy was acquired, followed immediately by the oral administration of perchlorate. One hour later, a second scintigraphy was obtained. After correction for radioisotope decay, discharge can be evaluated by comparing the counts before and after perchlorate. Thyroid scan in a patient with a positive discharge test before ( A) and after ( B) perchlorate. Thyroid scan in a patient with a negative perchlorate test before ( C) and after ( D) perchlorate.