Hypothyroidism is a common disorder, which is mainly treated in primary rather than secondary care. Once daily thyroxine replacement restores euthyroidism in most patients; some patients, however, remain hypothyroid despite adequate thyroxine replacement. Non-compliance is the most common cause of lack of response to thyroxine treatment. We describe two cases of primary hypothyroidism in which daily thyroxine treatment did not restore biochemical euthyroidism but once weekly thyroxine treatment was successful. In addition we review the evidence and discuss the differential diagnosis of lack of response to thyroxine treatment. Once weekly thyroxine treatment can be a safe, well-tolerated, and effective therapy for patients with non-compliance.
