Optimisation of thyroid hormone replacement using an automated thyroid register

The high prevalence of thyroid dysfunction requires an efficient and effective means of monitoring and adjustment. We compared the current network of 12,524 patients with thyroid dysfunction with register data prior to 1991 to examine the precision of thyroxine replacement in patients with hypothyroidism and assess locally changing trends in treatment of hyperthyroidism. Since 1991, due to the associated adverse effects of a suppressed thyroid-stimulating hormone (TSH) (<0.03 mU/l), the network has facilitated a significant reduction in the proportion of thyroxine-treated patients with TSH suppression from 58.5% before 1991 to 9.2 +/- 3.8% thereafter. Since 1991, there has been an increased use of radioiodine by 14.3% [95% confidence interval (95% CI): 10.6-17.8] and a reduced use of thyroidectomy by 12.3% (95% CI: 8.8-15.8) to treat hyperthyroid patients compared with before 1991. Between the two treatments, there were no differences in subsequent rates of hypothyroidism or mean thyroxine dosage.