What is iatrogenic hypothyroid?

Thyroidectomy (occurs 2-4 weeks after thyroidectomy due to 7 day half life of thyroxine) Radioiodine (I-131 for grave's can cause it months or years after admin) External neck irradiation (doses 25 Gy or more, effect is dose dependent, gradual onset, most people are subclinical for several years)