TPO and hypothyroidism: The thyroid workup revealed profound hypothyroidism (ultra-sensitive thyroid-stimulating hormone (uTSH) at 68.49 μIU/mL, severely depressed free T4 at <0.4 ng/dL) of autoimmune origin, confirmed by a high positivity for anti-thyroid peroxidase (anti-TPO) antibodies (>1,000 IU/mL) and anti-thyroglobulin antibodies (85 IU/mL).