Clinical presentation: A 33-year-old woman was referred for follow-up evaluation of a hypothyroidism has been known for eleven years.

Palpation: no abnormality.

Hormonal investigation: TSH 2.76 mIU/L on daily 75 microgram levothyroxine. The aTPO level was 883 U/mL 3 years ago.

Ultrasonography. The thyroid was hypoechogenic and presented fibrotic changes.

Diagnosis: Hashimoto's thyroiditis. Hypothyroidism.

Suggestion: yearly TSH determination.