First examination (1st and 2nd rows of images):

Clinical presentation: a 39-year-old woman requested a second opinion. She was referred for an evaluation of hyperthyroidism (TSH undetectable, FT4 39.3 pM/L) 2 weeks prior the present examination. Daily 20 mg methimazole therapy was advised but the patient did not start with the thyrostatic therapy. She lost 6 kg in weight and had palpitation.

Palpation : no abnormality.

Functional state: moderate degree of hyperthyroidism with TSH 0.01 mIU/L, FT4 46.3 pM/L.

Ultrasonography: around 40% of the thyroids were hypoechogenic. The vascularization was decreased.

FNAC disclosed Hashimoto's thyroiditis.

We performed TsAb test which proved to be elevated: 12 U/L (normal value below 1.5). Anti-TPO 102 U/mL.

Final diagnosis: Hashimoto's thyroiditis. Hashitoxicosis with great probability. Taking all circumstances into account, we advised not to treat the elevated hormone-levels.

Follow-up examination 4 weeks later:

Clinical presentation: the patient felt better, she gained 3 kg back.

Results of blood tests: TSH undetectable, FT4 15.5 pM/L.

Follow-up examination 3 month later:

Results of blood tests: TSH 6.08 pM/l, FT4 9.06 pM/L.

Follow-up examination another 3 month later:

Results of blood tests: TSH 3.77 mIU/l, FT4 12.1 pM/L.

Follow-up examination 31 months after the initial investigation (3rd row of images):

Clinical presentation: the patient had no complaints.

Palpation: no abnormality.

Functional state: TSH 9.43 mIU/L, FT4 10.0 pM/L.

Ultrasonography: the thyroid was larger compared with the initial examination. Except for the vascularization became increased, the sonographic pattern remained unchanged.

Replacement therapy was started.

Comments.

1. We think that the performance of ultrasound is mandatory in the event of moderate degree of hyperthyroidism without thyroid associated orbitopathy. We have found that decreased vascularization on ultrasound is a stronger argument against active hormone-producing process than elevated TsAB for that. Moreover, the performance of FNAC is very useful in such cases and may decide the differential diagnostic problem.

2. The patient presented a typical course of the so-called hashitoxicosis. A hyperthyroid phase was followed by a hypothyroid phase and months later the thyroid spontaneously became euthyroid.