Endocrine Abstracts

Objective: In patients with thyroid carcinoma, optimal thyroid hormone control, often with the aim of suppressing TSH levels, remains an essential component of tumor therapy. However, there are several factors, such as the use of pantoprazole or gastrointestinal diseases, showing a negative impact on absorption of levothyroxine and resulting in higher levothyroxine doses to achieve the desired levels.

Methods: We established a questionnaire with 16 variables on possible influencing factors (including pantoprazole intake, gastrointestinal diseases) in daily routine and initially analyzed the responses of 30 thyroid cancer patients.

Results: Of the 30 patients aged between 22-83 years (median 54 years; 15 female, 15 male) who were on levothyroxine for 0.5-39 years (median 4.5 years), 18 patients reported suffering from concomitant diseases, 20 confirmed regular additional medication intake, of whom 7 were taking pantoprazole and 2 taking iron supplements in parallel. 15 patients indicated a time interval of additional medication intake between 0-12 hours (median 1.5 h). 15 respondents reported suffering from occasional and/or regular gastrointestinal complaints, 3 patients had undergone gastrointestinal tract surgery.

Conclusions: The preliminary evaluation of our study on the presence of factors influencing the absorption of levothyroxine in thyroid cancer patients shows that the majority of patients have potentially influencing variables that are often hardly taken into account in routine clinical practice and can lead to a less than optimal setting. The treating physicians should be aware of such influencing factors.