Persistent Hypothyroidism Despite Standard Levothyroxine Treatment: A Case Study of Tissue Hypothyroidism

Despite hormone replacement therapy with levothyroxine sodium, some patients continue to complain of overt signs and symptoms of hypothyroidism, despite having normal labs. In some cases, there is no identifiable correlation with comorbidity and/or medication interfering with an optimal response; tissue hypothyroidism may be the reason for the observed signs and symptoms in these patients. We report a case of a 54-year-old Afro-Caribbean female who has been diagnosed with hypothyroidism for the past 26 years but was started on hormone replacement therapy with levothyroxine after bilateral partial lobectomy 19 years ago. The patient is currently on the standard levothyroxine therapy in tablet form, yet for the past 16 years have been complaining of persistent signs and symptoms of hypothyroidism; fatigue, dry skin, brittle hair and nails, cold intolerance, constipation, and unintentional weight gain. Normal laboratory findings and thyroid function tests confirm that the patient is given optimal doses of treatment. This case may suggest the presence of tissue resistance to levothyroxine, resulting in the persistence of signs and symptoms of hypothyroidism.