BACKGROUND:  Helicobacter pylori infection is a most frequent cause of chronic 
gastritis. H. pylori may decrease absorption of oral thyroxine by decreasing 
gastric acid secretion in the stomach. In this study, we aimed to investigate 
the change in thyroid function tests of the cases after H. pylori eradication 
who were not responding to high doses of thyroxine treatment before H. pylori 
eradication.
METHODS:  Hypothyroid cases who were not responding to high doses of thyroxine 
among the ones presented to Endocrinology and Gastroenterohepatology Clinics of 
Sisli Etfal Training and Research Hospital between 2009 and 2010 were included 
in the study. Thyroid function tests were performed two times in all cases 
before and after H. pylori eradication. Duodenal, antral and corporal biopsies, 
and jejunal aspirates and biopsies were taken during upper gastrointestinal 
system endoscopies performed in all patients. Cases without intestinal pathology 
were included in the study.
RESULTS: Serum thyrotropin (TSH), free T3, and free T4 values before H. pylori 
eradication were 30.5 ± 28.8 IU/mL, 2.64 ± 0.56 pg/mL, and 0.92 ± 0.32 ng/mL, 
respectively, and after eradication were found to be 4.2 ± 10.6 IU/mL, 3.02 ± 
0.61 pg/mL, and 1.3 ± 0.34 ng/mL, respectively (p values <.001, .002, and <.001, 
respectively). After H. pylori eradication treatment, TSH decreased in all of 
the cases, factitious thyrotoxicosis developed in % 21 of these cases.
CONCLUSION: In hypothyroid cases, H. pylori gastritis may be responsible for an 
inadequate response to the treatment. H. pylori eradication in the cases 
receiving high doses of thyroxine has a risk for thyrotoxicosis.