Clinical presentation: A 45-year-old woman was referred for follow-up investigation. She was treated with daily 200 microgram levothyroxine but the TSH-level was high.

Palpation: no abnormality.

Laboratory test: TSH 6.51 mIU/L.

Ultrasonography revealed an atrophic thyroid. The lobes were echonormal and had numerous small discrete hypoechogenic areas. The left thyroid bed contained a thickened fiber of the sternocleidomastoid muscle.

We suggested to increase the dose of levothyroxine to daily 300 microgram.