Clinical presentation: A 25-year-old woman requested an evaluation because her mother had hypothyroidism.

Palpation: The thyroid was moderately firm without any palpable nodules.

Laboratory tests: TSH 1.57 mIU/L, aTPO 317 U/mL.

Ultrasonography revealed a minimally-moderately hypoechogenic thyroid having several more hypoechogenic tiny areas.

Diagnosis: Hashimoto's thyroiditis.

Suggestion: TSH-determination in a year, in the event of pregnancy at once.