Aim
We present the case of a 16-year-old female referred to a peripheral hospital outpatient endocrinology clinic with severe hypothyroidism (TSH 150) and apparent resistant to high-dose Thyroxine. Despite taking 250 mcg daily, and increasing to 400 mcg, there was minimal biochemical improvement and significant side effects. The aim of this case report is to explore the potential reasons for thyroxine resistance, and detail the management strategy and clinical outcome.
Methods
This is a retrospective review and analysis of a case referred to the outpatient endocrinology clinic at a peripheral hospital in outer-metropolitan Western Australia. The patient experienced care delays due to her age and transition from pediatric to adult services, which led to referral redirection based on residence. Comprehensive assessments were conducted, including detailed thyroid function tests, evaluation for absorption issues, and investigation for metabolic resistance.
Results
The patient initially received outpatient management. Her Thyroid Function Tests (TFTs) consistently showed elevated TSH levels indicative of under-replacement of Thyroxine despite reported compliance. Physical examination was largely unremarkable except for pallor and a palpable, symmetrical enlarged thyroid. Persistent hypereosinophilia and symptomatic iron deficiency despite an iron infusion two months prior were also noted. A comprehensive inpatient assessment was initiated, including further TFTs, nutritional and metabolic screening, stool studies for parasites, and serology for strongyloides and threadworm.
Conclusion
This case underscores the complexity of managing hypothyroidism and Thyroxine resistance in the context of adolescence, and other co-morbidities. The patient's persistent symptoms and abnormal TFTs necessitated a comprehensive inpatient assessment and alternative management approach in order to explore potential absorption and metabolic factors affecting Thyroxine efficacy. Further studies are warranted to elucidate mechanisms of resistance and optimize management strategies in similar cases. The patient’s clinical course following a revised treatment plan highlights the importance of individualised care.