OBJECTIVES:Hypothyroidism occurs between 1-2% of the general population, generates significant morbidity and requires treatment with levothyroxine continuously. The aim was to determine the effectiveness, adherence and safety of levothyroxine therapy in a sample of patients diagnosed with hypothyroidism.

METHODS: Follow-up study of a cohort in patients diagnosed with hypothyroidism in continuous management with levothyroxine between August 2016 and June 2017. A representative sample was taken and sociodemographic, clinical, and adverse reactions variables were identified. Morisky-Green adherence test was applied and effectiveness was determined by measuring TSH.

RESULTS: We evaluated 330 patients with an average age of 62.9 ± 15.1 years and a predominance of females (76.1%). A total of 235 (71.2%) had TSH levels in the euthyroid state range, 64 (19.4%) were classified as hypothyroid and 31 (9.4%) hyperthyroid. The median TSH was 2.09 mIU / L, (interquartile range: 1.16mUI / L-3.61mUI / L). 85.8% (n = 283) reported having complete adherence to the medication, 29 (8.8%) moderate and 18 (5.4%) were classified as not adherent. Having a diagnosis of anemia (OR: 0.37, 95% CI: 0.15-0.98) or needing doses higher than 100 μg / day (OR: 0.47, 95% CI: 0.28-0.80) raised the probability of not controlling hypothyroidism.

CONCLUSIONS: A high proportion of patients are controlled and are very often adherent to levothyroxine therapy. These data generate confidence in the quality of care and the medicines they are receiving.