TPO and hypothyroidism: When the patient presents with TSH >10 mIU/L or between 5–10 mIU/L with positive anti-TPO or clinical symptoms of hypothyroidism, replacement treatment is required (starting with 0.8 mcg/kg/d, 25–50 mcg/d in older people or those with comorbidities, mainly cardiac, and scaling up to 1.6 mcg/kg/d approximately).