Use of a pharmacological indicator to monitor compliance with thyroxine.

Poor compliance with medication is often suspected, but difficult to confirm. The compliance of fourteen newly diagnosed hypothyroid patients was assessed using both TSH levels and low-dose phenobarbitone as a pharmacological marker. The study confirms the value of phenobarbitone as an indicator of compliance over a protracted period and suggests that it could be used to differentiate under-treatment from poor compliance.