Are patients with primary hypothyroidism in India receiving appropriate thyroxine replacement? An observational study

BACKGROUND: A large proportion of patients worldwide under treatment for hypothyroidism with thyroxine show suboptimal Thyroid Stimulating Hormone (TSH) values. There is a paucity of Indian data on ‘out-of-range’ TSH values in patients with primary hypothyroidism receiving levothyroxine treatment. AIM: To assess the percentage of primary hypothyroid patients with abnormal thyroid function despite being prescribed levothyroxine for at least 2 m. MATERIALS AND METHODS: A cross-sectional, single visit, observational study in adult patients with primary hypothyroidism on treatment with levothyroxine for at least 2m was undertaken across 10 cities in India. Compliance to thyroxine therapy was assessed by interviewing the subjects and their quality of life was assessed by administering the SF-36 questionnaire. A random blood sample (5ml) was drawn from the study subjects during the same visit for assessing serum TSH levels. TSH levels were correlated with the current dose of levothyroxine. RESULTS: A total of 1950 subjects (mean age 41.4 ± 11.17 years; female 81.2%, male 18.8%) with primary hypothyroidism were enrolled in the study. Of the 1925 subjects in whom TSH values were available, 808 (41.97%) were under-treated (TSH > 4 mIU/L) and 243 (12.62%) were over-treated (TSH < 0.4mIU/L). The mean dose of thyroxine in this study was 1.23 μg/kg/day (±0.85). Majority of subjects (90.79%) were compliant/moderately compliant to thyroxine therapy. Age and autoimmune hypothyroidism were the factors that had significant impact on serum TSH. Subjects with abnormal TSH had significantly lower scores for role limitation due to emotional problems (P = 0.0278) and due to physical health (P = 0.0763). CONCLUSION: This study concluded that around half (54%) of known hypothyroid subjects had out-of-range serum TSH despite being treated with levothyroxine for at least 2m. The mean daily dose of thyroxine (1.23 μg/kg ± 0.85) was less than the recommended full replacement dose.