A 24-year-old woman comes to the clinic after 3 weeks of heat intolerance and increased appetite. Despite increased caloric intake, she has lost weight. The patient's medical history is insignificant, and she takes no prescription or over-the-counter medications. She does not use tobacco or illicit drugs, and consumes alcohol only on rare occasions. The patient's last menstrual period was 3 days ago and was unusually light. Temperature is 37.2 C (99 F), blood pressure is 130/75 mm Hg, pulse is 110/min and regular, and respiratory rate is 14/min. On examination, the thyroid gland is mildly enlarged, mobile, and nontender. Cranial nerve examination is normal, although there is mild lid lag. Laboratory results are as follows: Radioactive iodine uptake is

Question

A 24-year-old woman comes to the clinic after 3 weeks of heat intolerance and increased appetite.  Despite increased caloric intake, she has lost weight.  The patient's medical history is insignificant, and she takes no prescription or over-the-counter medications.  She does not use tobacco or illicit drugs, and consumes alcohol only on rare occasions.  The patient's last menstrual period was 3 days ago and was unusually light.  Temperature is 37.2 C (99 F), blood pressure is 130/75 mm Hg, pulse is 110/min and regular, and respiratory rate is 14/min.  On examination, the thyroid gland is mildly enlarged, mobile, and nontender.  Cranial nerve examination is normal, although there is mild lid lag.  Laboratory results are as follows:  Radioactive iodine uptake is <5% (normal: 8%-25%).  The thyroid gland is not visualized on thyroid scan.  Which of the following is the most likely diagnosis for this patient?

Quizplus · Accepted Answer

11ec25c8_d3b9_0ea7_bc81_3788cc20eb4a_MD0003_00 This patient has painless thyroiditis (silent thyroiditis), characterized by acute thyrotoxicosis with mild thyroid gland enlargement and suppressed TSH. Painless thyroiditis is an autoimmune disorder thought to be a variant of Hashimoto thyroiditis, although the latter classically presents with chronic hypothyroidism. A similar disorder can also be seen within a year following pregnancy but would be properly termed postpartum thyroiditis. The follicular inflammatory reaction in painless thyroiditis may occasionally lead to a persistent hypothyroid phase, but most patients recover normal thyroid function. Patients with hyperthyroidism and a suppressed TSH should undergo thyroid radioiodine scintigraphy to distinguish painless thyroiditis from Graves disease. With painless thyroiditis, radioiodine uptake is decreased suggesting the release of preformed thyroid hormone. In contrast, Graves disease causes hyperthyroidism due to increased synthesis of thyroid hormone. Radioiodine uptake will be diffusely increased, and extra-thyroidal manifestations (eg, exophthalmos, pretibial myxedema) are often present (Choice A). exophthalmos (Choice C) Struma ovarii is a very rare cause of thyrotoxicosis and is due to production of thyroid hormone by an ovarian teratoma. It typically presents in women over age 40 with a pelvic mass, ascites, or abdominal pain. The thyroid gland is not enlarged with this condition. (Choice D) Subacute thyroiditis (granulomatous or De Quervain thyroiditis) also causes hyperthyroidism with a suppressed TSH and decreased radioiodine uptake. However, it is associated with a painful, tender goiter. (Choice E) Nodular thyroid disease is a more common cause of hyperthyroidism in older individuals. A thyroid scan will show increased uptake in either a focal (toxic adenoma) or heterogeneous (toxic multinodular goiter) pattern. toxic adenoma Educational objective: Painless thyroiditis (silent thyroiditis) is characterized by acute thyrotoxicosis with mild thyroid enlargement and suppressed TSH. Thyroid scintigraphy shows decreased radioiodine uptake. References: Subacute, silent, and postpartum thyroiditis. (http://www.ncbi.nlm.nih.gov/pubmed/22443972)

A 24-Year-Old Woman Comes to the Clinic After 3 Weeks