Demographic and Clinical Factors Associated With the Appropriate Target Thyroid-Stimulating Hormone Values in Patients With Primary Hypothyroidism Treated With Levothyroxine

Abstract

Background: Hypothyroidism control is inadequate in up to 30-40% of patients. This study aimed to determine the control rate of primary hypothyroidism and the demographic and clinical factors associated with the hypothyroidism control. Methods: An observational and retrospective study was conducted between January 2014 and October 2015. Data were obtained from 174 medical records. Regarding hypothyroidism control analysis, patients were subdivided into two groups: the appropriate control group and the inappropriate control group. Autoimmune and post-surgical hypothyroidism secondary to benign nodular thyroid disease (BNTD) was classified as of benign etiology, and differentiated thyroid carcinoma (DTC) as of malignant origin. Results: The majority of patients consisted of women (93.68%), with a mean age of 55.53 ± 14.13 years old. The most common etiology was of autoimmune origin (41.95%). Adequate control of hypothyroidism was found in 55.17% of patients. Patients who had longer disease duration (P = 0.002), who kept using the same brand of levothyroxine (P = 0.001) and who were non-smokers (P = 0.004) had better control, and hypothyroidism from benign etiology also tended to be associated with better control (P = 0.08). Conclusions: Primary hypothyroidism still has a high percentage of poor control seen worldwide, despite its relatively simple treatment. In this study, almost 50% of the patients had inadequate control of hypothyroidism. The factors associated with good control, both of benign and malignant origin, were related to the use of the same brand of levothyroxine and to not smoking, and the benign etiology group tended to correlate with better treatment control. J Endocrinol Metab. 2016;6(4):109-115 doi: http://dx.doi.org/10.14740/jem367w