Persistent hypothyroidism despite optimal therapy: time to rethink
George Varughese, Abd Tahrani, Tahir Khan, Julie Davis, Richard Clayton & Fahmy Hanna
We report a 47-year old lady who was initially diagnosed to have primary hypothyroidism nearly four years ago; on treatment with levothyroxine sodium (LT4) 150 μcg daily. Despite reasonable doses of LT4, and being fully compliant with her therapy, at no stage her TSH was less than 20 mU/L (Table-1). Malabsorption was ruled out and there were no clinical features to suggest this. When she was reviewed in the endocrine clinic, she was advised to take the tablets on an empty stomach (rather than with the white tea and breakfast that she regularly had been having immediately following her LT4 tablets). On subsequent follow-up four months later, the thyroid function tests (TFTs) had improved on the same dose of LT4 and she had lost nearly 2 kgs in weight despite the christmas effect as she described it, and felt well in herself. Subsequent TFTs continue to remain in the reference range with the altered timing of intake of LT4. Timing of treatment in patients with thyroid disease is extremely important and should be explored in detail, when TFTs fail to improve despite therapy. The patient described above was not on any other medication that would have interfered with the bioavailability or pharmacokinetics of LT4. We suggest that an alternative cause should be considered in such patients, as many a time other factors affecting the management of thyroid dysfunction are less commonly perceived in clinical practice and usually patient compliance is suspected in these circumstances. This case report reminds clinicians to be aware of unusual causes for persistent abnormalities in TFTs despite optimal treatment.
Thyroid functions over the years
|Year||TSH (0.35.0 mU/L)||T4 (1022 pmol/L)|