Endocrine Abstracts

Background: Poor adherence with thyroxine treatment is a common problem faced by endocrinologists the world over. Abnormally elevated TSH levels, with rising levels of treatment is an ongoing management challenge, especially with patient insistence of compliance. There are a number of investigative tools advocated. We present a case managed through an observed thyroxine absorption test.

Methods: A 36-year-old woman was referred by her primary care practitioner, due to a persistent elevated TSH, leading to a prescribed dose of 450 μg of thyroxine daily. The patient insisted on good compliance with medication and after excluding malabsorption conditions, we arranged an observed thyroxine absorption test. We arranged for the patient to present to the hospital daily for 5 days; be watched taking the prescribed dose and her mouth checked to ensure swallowing and the patient then was not allowed the visit the bathroom for an hour after swallowing.

Results: The patient consented 2 weeks prior to the investigation. At the beginning of the 5-day her free hormone levels increased significantly. At the beginning of the 5-day, bloods later demonstrated FT₄ 60.9, FT₃ 14.4 and TSH 0.03, confirming she had now started taking her tablets. She complied with the thyroxine absorption test and the repeat blood investigations at the end of the 5 days later demonstrated FT₄ >100, FT₃ 21.4 and TSH 0.03, thus confirming compliance with treatment and over-treatment with thyroxine.

Conclusions: The investigation demonstrated an over-prescription of thyroxine due to poor-compliance with treatment. We recommended the cessation of treatment for 14-day then recommencement at a lower dose with repeat testing after 2 months to test compliance. For difficult to manage poor-compliance cases, an observed thyroxine absorption test can be invaluable in identifying inadequate treatment due to poor compliance.