Clinical presentation: A 45-year-old woman visited us for a follow-up. She was treated for Graves' disease 6 years ago. She had no complaints.

Palpation: no abnormality.

Ultrasonography. The thyroid was minimally-moderately hypoechogenic and presented with fibrosis of minimal degree. The vascularization was average.

Hormonal investigation: subclinical hypothyroidism (TSH 5.72 mIU/L, FT4 14.9 pM/l, aTPO 81 U/mL).

Suggestion: TSH determination in six months.

Six months later the TSH-level rose to 8.1 mIU/L when we started with replacement therapy.

Comment. In the event of a subclinical hypothyroidism in general we suggest a replacement therapy if the TSH exceeds 5 to 6 mIU/L at two subsequent checks except for woman in childbearing age and for those whose thyroid is enlarged.