ABSTRACT
History A 65-year-old man with a history of psychotic depression who has been treated with lithium, olanzapine, diazepam, amlodipine for hypertension and simvastatin for hypercholesterolaemia was found to have abnormal thyroid function tests on routine monitoring. His lithium concentrations were in the therapeutic range. Thyroid function tests returned to normal on thyroxine replacement at a dose of 100 μg/day. He was admitted having become increasingly erratic in his behaviour and unsteady on walking. He was confused and unable to give a history.
