HealthMap

Effects of Corticosteroids on Thyroid Hormone Conversion

• Suppression of Conversion:
• Corticosteroid therapy, such as high-dose glucocorticoids, can significantly inhibit the peripheral conversion of thyroxine (T4) into the active hormone triiodothyronine (T3).

• Elevation of Reverse T3:
• This impaired enzymatic pathway often leads to a decrease in active T3 levels and a concurrent increase in the production of reverse T3 (rT3), an inactive metabolite.

• Impact on Thyroid Panel Results:
• Clinically, this suppression can result in laboratory findings that mimic euthyroid sick syndrome, showing lowered T3 and elevated rT3 levels, while thyroid-stimulating hormone (TSH) usually remains within the normal range or is only transiently suppressed.