A middle-aged woman presented with malaise and cold intolerance. She had radioactive iodine treatment for her thyrotoxicosis more than 10 years ago but defaulted follow-up shortly after treatment. Her thyroid function showed a fT4 of 5 pmol/L (N: 12-23 pmol/L) with a TSH of 150 mIU/L (N: 0.35 – 4.5). She was treated as post RAI hypothyroidism with thyroxine replacement.