Endocrine Abstracts

Introduction: The frequency of toxic multinoduler goiter (TMNG) is different among the countries depending on an intake of iodine, but it is said to be ~1% of adenomatous goiter in Japan. In addition, the frequency of TSH-secreting pituitary adenoma (TSHoma) is rare with 0.5–1.0% of pituitary gland tumor. There is no report that TMNG coexists in TSHoma so far.

Case: A 58 years old female was complained swelling of thyroid and palpitation. We found several nodules which were low echogenic masses of up to 28 mm on both thyroid lobes by cervical sonography. Her blood tests showed hyperthyroidism (fT₃ 6.3 pg/ml, fT₄ 2.3 ng/dl, TSH 3.20 μIU/ml, TgAb 10 IU/ml, TPOAb 5.1 IU/ml, HTg 167.6 ng/dl, TRAb (ECLIA) 0.3 IU/l). From above data which is syndrome of inappropriate secretion on TSH, we underwent her pituitary gland MRI, then we found the 8 mm mass. A TRH stimulation test: TSH (μIU/ml) was 4.258 (0 min), 5.496 (30 min), 5.303 (60 min). We diagnosed TSHoma and introduced her to a brain surgeon. She underwent a trans-sphenoidal neurosurgery by an endoscope. Though TSH was fallen back to 0.044 μIU/ml, fT₃ and fT₄ values were continued high even after 3 months of surgery. Therefore she was referred back to us for a close investigation of thyrotoxicosis. As the purpose of thyrotoxicosis differentiation diagnosis, she administered ¹²³I for thyroid scintigraphy. There were the hot uptake regions of both lobes and we diagnosed TMNG. After she took 500 MBq of ¹³¹I, her thyroid function returned to normal in a few months.

We also examined the thyroid hormone before treatment of 8 TSHoma cases that we experienced in our hospital. There was no difference of thyroid function between TSHoma alone and this patient.

Conclusion: TSHoma has many invasive cases and there are a lot of recurrence cases after surgery. Because it is difficult to deny complication of TMNG and TSHoma just from thyroid function, we think there might be more patients like this case.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.