Concentrations of plasma lipids and apolipoproteins, paraoxonase-1 activity, and cholesterol efflux were measured in 27 patients with differentiated thyroid carcinoma who underwent total thyroidectomy and radioactive iodine (RAI) treatment, at 3 distinct times: After surgery (baseline subclinical hyperthyroid state), on the day of undergoing RAI treatment (overt hypothyroid state), and 3 months post-RAI treatment (subclinical hyperthyroid state).