Berenice Pena AparicioInstituto Nacional de Cardiología Ignacio Chávez, Mexico
Title: Association of Antithyroid Antibodies with the Development of Manifest Hypothyrodism in Subjects with Subclinical Hypothyroidism
Background: Subclinical Hypothyroidism (SCH) is defined as the increase in serum levels of TSH >4.0 mu/l with normal values of free thyroxine (T4L 0.8 - 1.7 ng/dl). SCH has a prevalence of 0.7 to 16% and a progression to manifest hypothyroidism (MH) of 2 to 6% per year. Hashimoto thyroiditis is the main cause of SCH and is characterized by the presence of thyroid anti peroxidase antibodies (TPOAB). This study aimed to determine the association of TPOAB with the development of MH in mexican subjects with SCH and to evaluate the frequency of SCH persistence, evolution of MH, and regression to euthyroidism (EU) in these subjects.
Methods: Basal concentrations of TPOAB, TSH, and T4L were determined in serum samples of subjects with SCH followed for 6.2 years. Prevalence of SCH, EU, and MH was defined after follow-up. Multivariate logistic regression analysis was used to evaluate the association of TPOAB with the development of MH and the OR was calculated (95% CI).
Results: 226 subjects were included, average age of 55.1 ± 8.5 years, 65% women. The frequency of TPOAB in the whole population was of 22.6%. After 6.2 years of follow-up, 68 subjects (30.1%) reverted to EU, 56 (24.8%) evolved to MH, 102 (45.1%) remained with SCH. Compared with the subjects that reverted to EU and with those remaining in SCH, subjects with MH had a higher TPOAB (17.6%, 18.6%, and 35.7%, respectively; p = 0.025). The prevalence of TPOAB, tabaquism, age and gender were considered for the multivariate analysis. Results: the presence of TPOAB confers a 2.8-times higher risk (95% CI: 1.24-6.56) for the development of MH.
Conclusion: A positive and independent association of TPOAB with the development of MH was found. Mexican subjects with SCH and TPOAB have 2.8-times higher risk to develop MH after 6.2 years.
Berenice Pena has completed her Specialty in Clinical Endocrinology and Master's in Medical Sciences with Honorable Mention at the National Autonomous University of Mexico (UNAM). She is assigned and Coordinator of the Endocrinology Clinic, External Consultation of the Ignacio Chávez National Institute of Cardiology, Mexico City. Full Professor in Human Resources Training in Undergraduate and Postgraduate courses at UNAM. He actively carries out Clinical Research in the Cardiometabolic Area, in addition to being Professor in Chief of Academic Events of Continuous Medical Update at a National and International level.