A 32-year-old woman comes to the physician because of palpitations and mild anxiety over the last two months. She feels fatigued and has difficulty falling asleep at night. She delivered a healthy child 9 months ago, and her pregnancy was complicated by hypertension that resolved after delivery. She also gained excessive weight during pregnancy and has been trying to lose weight. Three months ago, she had an episode of acute sinusitis requiring antibiotic therapy. She has no other medical issues and does not take any prescription medications. She does not smoke cigarettes but drinks a few glasses of wine on the weekends.
Her blood pressure is 140/80 mm Hg and pulse is 100/min. Her BMI is 32 kg/m². The thyroid gland is non-tender and is not enlarged. The remainder of the physical examination is unremarkable.
Laboratory results are as follows:

Which of the following is the most likely diagnosis?

Question

A 32-year-old woman comes to the physician because of palpitations and mild anxiety over the last two months. She feels fatigued and has difficulty falling asleep at night. She delivered a healthy child 9 months ago, and her pregnancy was complicated by hypertension that resolved after delivery. She also gained excessive weight during pregnancy and has been trying to lose weight. Three months ago, she had an episode of acute sinusitis requiring antibiotic therapy. She has no other medical issues and does not take any prescription medications. She does not smoke cigarettes but drinks a few glasses of wine on the weekends.
Her blood pressure is 140/80 mm Hg and pulse is 100/min. Her BMI is 32 kg/m². The thyroid gland is non-tender and is not enlarged. The remainder of the physical examination is unremarkable.
Laboratory results are as follows:

Which of the following is the most likely diagnosis?

Quizplus · Accepted Answer

11ec193a_97bb_1357_853d_6143f53c5afd_MD0002_00 This patient presents with thyrotoxicosis that is most likely due to exogenous thyroid supplements. Obese patients often attempt to lose weight by taking dietary supplements that may contain high T3 amounts. Patients present with typical hyperthyroid symptoms (e.g., weight loss, palpitations, etc.), but do not have exophthalmos as seen in Graves' disease. However, patients may have lid lag. There is usually no goiter on examination, since the exogenous thyroid hormones inhibit TSH secretion and cause thyroid atrophy. Laboratory studies usually show high T3, low serum thyroglobulin levels, and suppressed TSH. Radioactive iodine uptake scan shows < 1% uptake (due to suppressed TSH). Serum thyroglobulin is low in exogenous thyroid hormone-induced thyrotoxicosis, but normal to elevated in all other causes of thyrotoxicosis. Fecal measurement of thyroid hormones has also been used to diagnose factitious thyrotoxicosis. (Choice A) Chronic autoimmune thyroiditis more commonly presents with hypothyroidism with elevated TSH and low T4. A small percentage of patients can present with hyperthyroidism, but those patients have suppressed TSH with elevated T4. This patient has normal T4 and elevated T3. (Choice C) Many patients with Graves' disease also do not have thyromegaly or extrathyroidal manifestations. Graves' disease can be ruled out in this patient based on serum thyroglobulin and radioactive iodine uptake, which are elevated in patients with Graves' disease. (Choice D) In most patients, postpartum painless thyroiditis occurs within 1-6 months after delivery. The radioactive iodine uptake is low, but in contrast to factitious thyrotoxicosis, serum thyroglobulin is elevated. (Choice E) Patients with subacute (de Quervain's) thyroiditis have moderate to severe pain and tenderness in the thyroid gland. Educational objective: Suppressed serum thyroglobulin differentiates factitious thyrotoxicosis from other causes of thyrotoxicosis associated with low radioactive iodine uptake. __________ References: Hyperthyroidism and other causes of thyrotoxicosis: management guidelines of the American Thyroid Association and American Association of Clinical Endocrinologists (http://www.ncbi.nlm.nih.gov/pubmed/21510801) Factitious thyrotoxicosis and herbal dietary supplement for weight reduction. (http://www.ncbi.nlm.nih.gov/pubmed/18363120)

A 32-Year-Old Woman Comes to the Physician Because of Palpitations