Objective: Although hypothyroidism is a common disease and its treatment is well defined, many patients do not have normal thyroid-stimulating hormone (TSH) levels. Understanding barriers and determinants of treatment adherence help to increase the success of the treatment.

Material and Method: This observational cross-sectional study was conducted at the outpatient clinics for Endocrinology and Internal Medicine. We administered a descriptive questionnaire and the 8-item Morisky Medication Adherence Scale consecutively by face-to-face interview method to 490 hypothyroid adult patients in outpatient clinics.

Results: The mean age of the patients was 49.3 ± 13.6 years and 459 (93.7%) of them were female. The mean duration of hypothyroidism was 8.3 ± 7.9 years. The mean medication adherence score was 2.9 ± 1.2. Ninety-four-point-seven percent of patients (n=464) were in the low adherence group, 5.1% (n=25) of patients were in the average adherence group, and only one patient (0.2%) was in the high adherence group. Thirty-seven-point-four percent of patients had TSH levels out of the normal range. Patients with TSH levels out of the normal range and patients with normal TSH levels had similar treatment adherence levels.

Conclusion: Despite the low treatment adherence of most patients with hypothyroidism, the ratio of patients with TSH levels in the normal range is high. The low education level, low socioeconomic status, comorbidities, and multiple drug use are associated with low treatment adherence.

Therapeutic adherence and compliance Hypothyroidism Treatment failure