Fig. 2.

shows the biochemistry of a patient with clinically severe GD managed with dose titration (DT) ATD and then block and replace (BR) ATD. The blue circles represent the free T4 concentrations and the red dots the TSH concentrations. The figures in red refer to the CBZ dose (mg). The instability of the thyroid hormone concentrations in this patient with severe GD ultimately resulted in a change from DT to a regimen comprising a larger dose of CBZ as part of a BR regimen. This clinical case and others like it support the use of a BR strategy but underline the importance of obtaining data from randomised trials (TRAb – thyroid receptor antibody titre; Free T4 normal range 10 to 21 pmol/l; TSH normal range 0.5 to 6 mU/l)