Clinical presentation: a 33-year-old woman with clinical signs of hyperthyroidism was referred for an evaluation.

Functional state: euthyroidism (TSH 1.65 mIU/L, FT4 13.8 pM/L).

Ultrasonography: multiple smaller hypoechogenic areas within the thyroid, i.e. the thyroid presented the so-called honeycombing pattern.

FNAC:   Hashimoto's thyroiditis.

Anti-TPO determination resulted in 692 U/mL.