Endocrine Abstracts

Multiple dose adjustments can sometimes be inefficient in reaching eumetabolic state in patients with hypothyroidism treated by levothyroxine sodium tablets.

We report a case of 46-year-old female who has been on levothyroxine sodium tablet replacement therapy since 2004 without ever reaching eumetabolic state. As sellar MRI ruled out pituitary adenoma, investigation perform absorption test with 300 mg levothyroxine and test was positive in aspect of presence of selective levothyroxine malabsorption. Initial endoscopies revealed chronic atrophic gastritis without excluding possibility for tumor presence. Serum CgA level was 521 mg/l. The final third endoscopy was successful in detecting the gastric submucosal change, confirmed by endoscopic ultrasound as submucosal lesion no larger than 12 mm located in the upper part of anterior gastric wall. Histological analysis of biopsy specimen confirmed lesion to be neuroendocrine tumor–Carcinoid tumour ventriculi, Chromogranin A +, NSE + ; synaptophhisin-, CK 7 + with Ki67 + in 2% tumour cell. Further imaging excluded its metastatic spreading, so the indication for surgical removal was established. Patient could not undergo surgery with TSH levels exceeding 100 mmU/l and free T4 lower than 5 pmol/l despite being on 300 mg of levothyroxine daily substitution regimen. Changing to a gel capsule formulation taken once a day at dose of 100 mg lead to a rapid TSH decreasement and thyroid hormones normalization, so the patient was surgically treated as eumetabolic. After six months, the patient had an unregulated thyroid status again (TSH 76.26 mIU/l, fT3 2. 7pmol/l, fT4 5, 1pmol/l). We did a control endoscopy and determined the level of gastrin (1432.0 pg/ml) and CgA (798 mg/l) and Gallium-68 Dotatate PET/CT scan thereafter (normal). We are now looking for Zollinger-Ellison syndrome and the patient is receiving 500 mg of levothyroxine sodium tablet.

This case suggests that gastric chronic inflammatory processes and neuroendocrine tumors as well may affect levothyroxine absorption.