Descripción
Supraphysiologic doses of corticosteroids such as prednisone can suppress TSH secretion and reduce T4-to-T3 conversion, complicating thyroid function interpretation during steroid courses.
Mecanismo
Glucocorticoids suppress thyrotropin-releasing hormone (TRH)-stimulated TSH secretion from the pituitary and inhibit peripheral conversion of T4 to the active T3 via reduced type 1 deiodinase activity.
Relevancia clínica
TSH suppression is typically transient and resolves upon steroid tapering; rarely causes clinically significant hypothyroid or hyperthyroid symptoms in patients on stable replacement.
Manejo clínico
Avoid interpreting thyroid function tests during acute high-dose corticosteroid courses; recheck TSH 4–6 weeks after steroid course is completed if adjustment is being considered.