Surveillance of TSH-Suppressive Levothyroxine Treatment in Thyroid Cancer Patients: TRH Testing Versus Basal TSH Determination by a Third Generation Assay

Objective, design and methods: Although TRH testing has been eliminated in the diagnosis of most benign thyroid diseases, it is still controversial whether or not it can be replaced by ultrasensitive determination of basal TSH for monitoring optimal TSH suppression in thyroid cancer patients. We compared basal and TRH-stimulated TSH values measured by a 2 nd generation assay (lower detection limit 0.1 mU/I) and by a 3 rd generation assay (lower detection limit 0.005 mU/l) in 209 thyroidectomized thyroid cancer patients under suppressive levothyroxine treatment. Results: In the 2 nd generation assay all patients had basal TSH values