Abstract
Background: Several epidemiological studies suggest firefighters are at risk for numerous site-specific malignancies, including thyroid cancer. However, it is not well known if chronic exposure to carcinogenic compounds or radio frequency radiation, increases the rate of thyroid nodules and/or affect the thyroid function in this high-risk occupational group. To gain a better understanding, we examine the rate of thyroid nodules and assess the presence of thyroid dysfunction in a sample of Florida firefighters. Methods: A cross sectional study design was conducted to evaluate 103 firefighters, with not known thyroid disease, who were assessed by a physician-performed, real time ultrasound protocol followed by a blood collection to evaluate TSH, Free T4, T4, T3, TPO and Tg antibodies. Additional data such as gender, age and race were also collected and analyzed. Results: Among the 103 firefighters who completed the study protocol, the sample mean age was 39.4+-7.6 years (range 26 to 60) 88.4% male, 87.6% Caucasian and 65% Hispanic. 8.7% of men and 33% of women were found to have thyroid nodules. Of the 20 participants with thyroid nodules only three nodules were above 1 cm, and only one was classified as high risk and met criteria for fine needle aspiration. 8.7 % of men and 33% of women were found to have +TPO antibodies. 18.6% of men and 25% of women were found to have isolated low T3. Conclusion: The prevalence of thyroid nodules, and of Hashimoto thyroiditis, among Florida firefighters, is comparable with the rate found in the general population based on previous epidemiological data. Surprisingly, we found that a significant number of subjects have isolated low T3. In this study, the level of Free T3 was not assessed, however since T4 was normal, we can conclude that the low T3 was not related to a low level of TBG. Low T3 is usually found in systemic illness and has been postulated as a prognostic factor in cardiovascular disease, chronic fatigue syndrome, survival after stroke, and Alzheimer’s disease. The clinical significance and the prevalence of Low T3 in a healthy population has not been well described. Further research is needed to fully understand the significance of this finding.