 Only one study examining the effects of fine titration of thyroxine dosage on wellbeing has been published. In this study, patients had significantly improved wellbeing if they took a dose of thyroxine which was 50 μg greater than their biochemically optimal dose as determined by a thyrotropin-releasing hormone test. In most cases, serum TSH was suppressed to below 0.2 mUL the limit of sensitivity of the assay on the thyroxine doses which improved wellbeing. This study was open-label and non-randomised, and the results therefore may have been affected by bias. 