A 34-year-old woman comes to the office with an uncomfortable sensation of rapid heartbeat for the last few weeks. She has had no associated chest pain or shortness of breath. The patient reports that her anxiety level has been high recently due to stress at work, and she has lost close to 2 kg (4.4 lb) during this time. Her last menstrual period was 5 days ago. Medical history is unremarkable, and she takes no medications. On examination, the thyroid gland is diffusely enlarged and nontender. Laboratory results are as follows: ECG shows sinus tachycardia at 120/min. Radioactive iodine uptake is

Question

A 34-year-old woman comes to the office with an uncomfortable sensation of rapid heartbeat for the last few weeks.  She has had no associated chest pain or shortness of breath.  The patient reports that her anxiety level has been high recently due to stress at work, and she has lost close to 2 kg (4.4 lb) during this time.  Her last menstrual period was 5 days ago.  Medical history is unremarkable, and she takes no medications.  On examination, the thyroid gland is diffusely enlarged and nontender.  Laboratory results are as follows:  ECG shows sinus tachycardia at 120/min.  Radioactive iodine uptake is <5%, and anti-thyroid peroxidase antibodies are present in high titers.  Which of the following is the most appropriate next step in management of this patient?

Quizplus · Accepted Answer

Explanation: 11ec25c8_d258_e25d_bc81_43a96a6e734d_MD0003_00 This patient has primary hyperthyroidism (elevated free T4, suppressed TSH), with signs of thyrotoxicosis including tachycardia, anxiety, and weight loss. Primary hyperthyroidism can result from: Overproduction of thyroid hormone (eg, Graves disease, toxic nodular goiter) Release of preformed hormone (eg, painless thyroiditis, subacute thyroiditis) These etiologies can be distinguished with radioactive iodine uptake (RAIU) scintigraphy, which will be increased in cases of hormone overproduction and low or undetectable in cases of release of preformed hormone. In this patient, the low RAIU and nontender goiter are most consistent with painless (silent) thyroiditis. Painless thyroiditis is associated with thyroid peroxidase autoantibodies and is considered a variant of chronic lymphocytic (Hashimoto) thyroiditis. It is similar to postpartum thyroiditis but by definition excludes patients within a year of pregnancy. Following a self-limited hyperthyroid phase, patients often develop a hypothyroid phase, which may persist or return to a euthyroid state. Painless thyroiditis does not require specific therapy. However, as hyperthyroidism causes adrenergic overstimulation, a beta blocker (eg, propranolol) may be prescribed to control symptoms, especially palpitations or tremulousness. (Choice A) Alprazolam is a benzodiazepine used primarily in the short-term treatment of anxiety. In this patient, blocking the effects of adrenergic hyperstimulation will likely relieve her symptoms, and additional symptomatic therapy may not be needed. (Choice B) Levothyroxine is required for the subset of patients who develop significant hypothyroidism. (Choices C and F) Methimazole works primarily by decreasing thyroid hormone production; RAI causes radiation-induced destruction of thyroid follicular cells. As a result, these treatments are used for thyrotoxicosis due to thyroid hormone overproduction but are not helpful for patients with excess release of preformed hormone. (Choice D) Prednisone is used to treat thyroid pain in patients with subacute (de Quervain) thyroiditis who do not respond to nonsteroidal anti-inflammatory drugs. Although subacute thyroiditis would also be associated with low RAIU, it presents with a painful, tender goiter and is typically preceded by an upper respiratory tract infection. Prednisone is also used in some patients with amiodarone-induced thyrotoxicosis. Educational objective: Painless thyroiditis is a variant of chronic lymphocytic (Hashimoto) thyroiditis. It is characterized by a self-limited hyperthyroid phase due to release of preformed thyroid hormone, followed by a hypothyroid phase or return to a euthyroid state. It does not require specific therapy, but a beta blocker may be prescribed to control symptoms due to hyperthyroidism (eg, palpitations, tremulousness). References: Subacute, silent, and postpartum thyroiditis. (http://www.ncbi.nlm.nih.gov/pubmed/22443972)

A 34-Year-Old Woman Comes to the Office with an Uncomfortable