Clinical presentation: A 50-year-old woman was referred for follow-up of hypothyroidism. Her GP initiated the examination because of low FT3 level. The patient has been treated for hypothyroidism for 7 years.

Palpation: no abnormality.

Laboratory tests: TSH 3.69 mIU/L, FT4 13.2 pM/L, FT3 2.77 pM/L on daily 62.5 microgram levothyroxine.

Ultrasound. The thyroid was moderately hypoechogenic and had several discrete areas which did not fit to nodules in pathological sense.

Suggestion: To continue with daily 62.5 microgram levothyroxine.

Comment. There is very limited sense to make an FT4 and practically no sense to perform an FT3 test if the TSH is normal.