Low uptake of 123I on the thyroid uptake scan would be an expected finding in: 1) A solitary toxic nodule 2) A multi-nodular toxic goitre 3) Amiodarone induced thyrotoxicosis type 1 4) DeQuervain's thyroiditis 5) Graves' thyrotoxicosis
Answers-4 DeQuervain's thyroiditis is classically associated with low or absent 123I (the 131 radioactive isotope of iodine) uptake. The others will have high or normal uptake. In particular type 1 amiodarone induced thyrotoxicosis may be distinguished from the thyroiditis of type 2 by the normal or high uptake scan.