Radio-iodine therapy and Helicobacter pylori infection.

BACKGROUND: Helicobacter pylori is the most important cause of gastritis and related morbidities. Following consumption, radioactive iodine accumulates considerably in the stomach. On the basis of this observation, we decided to determine whether the high radiation induced by radio-iodine in the stomach is effective in the eradication of this infection. METHODS: All consecutive patients with differentiated thyroid carcinoma, who were referred for radio-iodine therapy [dose 117.1 +/- 24.4 mCi (4.3 +/- 0.9 GBq), range 100-200 mCi (3.7-7.4 GBq)], were enrolled. To detect H. pylori infection, the urease breath test (UBT) was performed 1-2 h before radio-iodine consumption and the test was repeated 2 months later. RESULTS: Of 88 patients, 71 had pre-treatment positive UBT. Of these, 23 patients had negative post-treatment result, which means a significant reduction (26.1%, 95% CI 16.8-35.5%) in the number of positive UBT results in our treated population (32.4% of UBT-positive cases became UBT-negative). CONCLUSIONS: Considering the high prevalence of reinfection in developing countries, the therapeutic benefit would have been more considerable if the second UBT had been done with a lag time of less than 2 months. Although radio-iodine therapy is not a logical method for the treatment of patients suffering from H. pylori, our finding provides indirect evidence about the radiosensitivity of bacteria, the future clinical applications of which need to be further evaluated. Also this finding can be useful for the food industry, where radiation is used widely to sterilize food. Regarding the possibility of H. pylori suppression, we recommend not using UBT for screening for the infection for at least within 2 months following radio-iodine therapy.

[On-levothyroxine measurement of thyroglobulin is not a reliable test for the follow-up of patients at high risk for remnant/recurrent differentiated thyroid carcinoma].

INTRODUCTION: At present the most widely accepted tool for follow-up management of differentiated thyroid cancer (DTC) patients is serum thyroglobulin (Tg) measurement. It is not uncommon for the serum Tg level to be measured while the patient is taking thyroid hormones (on-treatment Tg measurement). The purpose of the study was to evaluate the accuracy of on-treatment measurement of serum Tg in detecting remnant/recurrent or metastatic disease in high-risk DTC patients. MATERIAL AND METHODS: We retrospectively analysed the medical records of 26 high-risk DTC patients and compared the on-treatment and off-treatment Tg levels of these patients. All patients were anti-Tg negative. Using off-treatment measurement of Tg as the gold standard, the results of on-treatment measurement of Tg in the diagnosis of remnant/recurrent disease were analysed for sensitivity, specificity, negative predictive value (NPV) and positive predictive value (PPV). RESULTS: The median serum Tg level under thyroid hormone suppressive therapy (on-treatment Tg) was 16.5 ng/ml and after withdrawal of thyroid hormone suppressive therapy (off-treatment Tg) was 95.0 ng/ml (P value = 0.001). In 6 patients (23%) the on-treatment Tg level missed the recurrence of the disease. Regarding the off-treatment Tg as the gold standard, the sensitivity, specificity, PPV and NPV of the on-treatment Tg measurement were 72.7%, 100%, 100%, and 40% respectively. CONCLUSION: Normal serum Tg level without TSH-stimulation (on-treatment) is not diagnostically reliable in the follow-up of DTC patients with a high probability of residual/recurrent or metastatic disease.