Clinical presentation: A 28-year-old woman was referred for a follow-up investigation. She was treated for hypothyroidism 3 years ago during pregnancy. The replacement therapy was discontinued after delivery and the TSH remained normal in the next 30 months. She had no complaints. The patient intended to become pregnant.

Palpation: no abnormality.

Laboratory tests: TSH 5.01 mIU/L, FT4 13,6 pM/l. The anti-TPO was 720 U/mL three years ago.

Ultrasonography revealed a minimally hypoechogenic thyroid presenting more hypoechogenic areas. The echogenicity index was around 25%. None of the hypoechogenic areas fit to a nodule in pathological sense.

Suggestion daily 50 microgram levothyroxine.