Thyrotoxicosis factitia: author's response

I would like to thank Chow et al. for their letter and agree fully with their comment that a thyroid Tc99 uptake scan cannot differentiate between thyrotoxicosis factitia due to exogenous thyroid hormone ingestion and thyroiditis.

We did not measure thyroglobulin in our patient¹ as we felt the combination of reduced uptake on the thyroid Tc99 scan, the lack of systemic features of viral thyroiditis and the documentary evidence of prescribed thyroxine, which had been denied by the patient was sufficient to make the diagnosis of thyrotoxicosis factitia due to exogenous thyroxine hormone ingestion.