A 66-year-old woman is seen in the outpatient clinic for follow-up. The patient has no current symptoms. She has a history of hypothyroidism and takes levothyroxine replacement therapy. The patient's other medical problems include hypertension and acid reflux disease. She underwent dual-energy x-ray absorptiometry 2 months ago, which was normal. Her TSH level is

Question

A 66-year-old woman is seen in the outpatient clinic for follow-up.  The patient has no current symptoms.  She has a history of hypothyroidism and takes levothyroxine replacement therapy.  The patient's other medical problems include hypertension and acid reflux disease.  She underwent dual-energy x-ray absorptiometry 2 months ago, which was normal.  Her TSH level is <0.01 mU/L.  Despite a long discussion, the patient refuses to decrease the dose of levothyroxine as lower doses make her feel "exhausted and sleepy all the time."
Which of the following is a possible complication of levothyroxine overreplacement in this patient?

Quizplus · Accepted Answer

A number of serious adverse effects are associated with overtreatment of hypothyroidism with levothyroxine, including excessive bone loss and cardiac arrhythmias (eg, atrial fibrillation). The risk of bone loss and arrhythmias from overtreatment is higher in older patients, particularly those with markedly suppressed TSH (<0.1 mU/L). Nonspecific symptoms (eg, fatigue, weight gain) in patients with hypothyroidism are frequently attributed to undertreatment, and patients often request supratherapeutic dosing of thyroid supplements to increase energy and facilitate weight loss. As a result, overtreatment of hypothyroidism is not uncommon in clinical practice but should be discouraged. Also, the addition of liothyronine in a patient who is biochemically euthyroid on levothyroxine is not associated with improved outcomes and is not indicated. However, dosing of levothyroxine to maintain TSH in the low-normal range is not associated with adverse effects and may be adequate to satisfy patient concerns. (Choice B) There is no proven association of dementia with thyrotoxicosis. Patients with severe thyrotoxicosis may have acute reversible changes in mental status ranging from mild inattention to loss of consciousness. (Choice C) Hypothyroidism increases LDL, whereas LDL levels decrease in thyrotoxicosis. (Choice D) Ophthalmopathy, characterized by an increase in volume of retro-orbital tissues with proptosis, is an extrathyroidal manifestation of Graves' disease but is not seen in other causes of thyrotoxicosis. Lid lag and lid retraction without proptosis can be seen with thyrotoxicosis due to any cause. (Choice E) A high TSH level is a risk factor for thyroid cancer, but a low TSH level may be protective. Educational objective: Overtreatment of hypothyroidism with levothyroxine is associated with an increased risk of excessive bone loss and atrial fibrillation. __________ References: Serum thyroid-stimulating hormone concentration and morbidity from cardiovascular disease and fractures in patients on long-term thyroxine therapy. (http://www.ncbi.nlm.nih.gov/pubmed/19906785)

A 66-Year-Old Woman Is Seen in the Outpatient Clinic for Follow-Up