Study Tips

USMLE® Step 2 Question of the Day: Thyroid management

Osmosis Team
Feb 28, 2024

We're back with a USMLE® Step 2 CK Question of the Day! Today's case involves a 35-year-old woman presents with unintentional weight loss, diarrhea, and proptosis. Vital signs show an elevated pulse and blood pressure. Lab results indicate low TSH, high free T4, and positive thyroid-stimulating immunoglobulin. What's the best next step in management?

A 35-year-old woman presents to the primary care clinic due to unintentional weight loss, diarrhea, excessive sweating, and occasional diplopia. Past medical history is unremarkable. Temperature is 37.4°C (99.3°F), blood pressure is 152/78 mmHg, pulse is 120/min, respiratory rate is 18/min, and oxygen saturation is 98% on room air. On physical examination, her thyroid gland is diffusely enlarged without nodules and non-tender, and her eyes exhibit significant proptosis with restrictive extraocular movements. Laboratory tests reveal a decreased thyroid-stimulating hormone (TSH) level, elevated free thyroxine (T4) level, and positive thyroid-stimulating immunoglobulin. Which of the following is the best next step in management?

A. Refer for thyroidectomy

B. Administer propylthiouracil (PTU

C. Administer oral glucocorticoids

D. Refer the patient for radioactive iodine ablation

E. Selenium

Scroll down for the correct answer!

The correct answer to today's USMLE® Step 2 CK Question is...

A. Refer for thyroidectomy

Before we get to the Main Explanation, let's see why the answer wasn't B, C, D, or E. Skip to the bottom if you want to see the correct answer right away!

Incorrect answer explanations

Today's incorrect answers are...

B. Administer propylthiouracil (PTU)

Incorrect: Propylthiouracil (PTU) is an antithyroid drug used in the treatment of hyperthyroidism. It is usually indicated in patients with mild hyperthyroidism, no orbitopathy, and a high likelihood of remission. In this patient with moderate ophthalmopathy, thyroidectomy is preferred.

C. Administer oral glucocorticoids

Incorrect: Although oral glucocorticoids can be used in the management of Graves ophthalmopathy, they do not address the underlying hyperthyroidism and are usually used in combination with other therapies in patients with mild orbitopathy.

D. Refer the patient for radioactive iodine ablation

Incorrect: Radioactive iodine ablation is a common treatment for Graves disease but is contraindicated in patients with moderate to severe ophthalmopathy as it can worsen eye symptoms.

E. Selenium

Incorrect: Selenium can be used in patients with mild orbitopathy in parts of the world where there is deficiency.

Main Explanation

This patient presents with classical symptoms of hyperthyroidism and a non-nodular thyroid in addition to positive thyroid-stimulating immunoglobulin, consistent with the diagnosis of Graves disease. Her ocular findings of proptosis and restricted extraocular movements with occasional diplopia are suggestive of moderate Graves ophthalmopathy, which is an indication for thyroidectomy. 

Treatment options for Graves disease include antithyroid drugs, radioactive iodine ablation, and thyroidectomy. The choice of treatment depends on the patient's symptoms, the severity of the disease, patient preferences, the presence of contraindications to therapy, and the presence of certain features like ophthalmopathy. Antithyroid medications like methimazole or propylthiouracil (PTU) inhibit the synthesis of thyroid hormones, providing a non-invasive, reversible treatment option. However, there is a high relapse rate with these medications once the medication is discontinued. 

Radioactive iodine ablation offers a permanent solution by destroying the overactive thyroid tissue but often results in hypothyroidism, necessitating lifelong thyroid hormone replacement. Radioactive iodine treatment is contraindicated in pregnant or breastfeeding women and in patients with Graves' ophthalmopathy, as it can exacerbate the condition. 

Surgery (total or subtotal thyroidectomy) is typically reserved for patients with large goiters causing compressive symptoms, suspicion of malignancy, and moderate or severe ophthalmopathy. It's also considered for those who are pregnant or cannot tolerate other treatment options. However, surgery carries risks, such as injury to the recurrent laryngeal nerves and parathyroid glands.  

table about graves disease's treatment and adverse effects


Major takeaway

Graves disease treatment options include antithyroid drugs, radioactive iodine ablation, and thyroidectomy. In patients with moderate to severe Graves ophthalmopathy, thyroidectomy is the preferred treatment.

References

Ross DS, Burch HB, Cooper DS, et al. 2016 American Thyroid Association Guidelines for Diagnosis and Management of Hyperthyroidism and Other Causes of Thyrotoxicosis [published correction appears in Thyroid. 2017 Nov;27(11):1462]. Thyroid. 2016;26(10):1343-1421. doi:10.1089/thy.2016.0229

––––––––––––

Want more  USMLE® Step 2 CK practice questions? 
Try Osmosis by Elsevier today! Access your free trial and find out why millions of current and future clinicians and caregivers love learning with us.

Ace your clerkships with clinical practice videos on Osmosis. Watch now.