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Self-Assessment Questions

Endocrinology

Hypothyroidism and Hyperthyroidism:
Review Questions


Sonia Ananthakrishnan, MD, and Elizabeth N. Pearce, MD, MSc

Dr. Ananthakrishnan is a clinical instructor of medicine, and Dr. Pearce is an assistant professor of medicine; both are at the Boston University School of Medicine, Boston, MA.



Choose the single best answer for each question.

1. A 33-year-old woman presents to the clinic with a positive home pregnancy test. The patient has a history of Hashimoto’s thyroiditis, which has been successfully managed with levothyroxine 125 g daily for the past 4 years; serum thyroid-stimulating hormone (TSH) levels have been between 0.5 and 1.5 µIU/mL (normal, 0.3-5.5 µIU/mL). She has a family history of thyroid disease, and her mother also takes levothyroxine. In the office, the pregnancy test is confirmed; this is her first pregnancy. To remain biochemically and clinically euthyroid, how should this patient be managed?
  1. Levothyroxine should be increased
  2. Levothyroxine should be decreased
  3. Triiodothyronine (T3) should be taken in addition to levothyroxine
  4. The pregnancy should be terminated
Click here to compare your answer.


Questions 2 and 3 refer to the following case.
A 65-year-old man returns to the clinic 3 months after routine blood tests revealed a serum TSH level of 0.08 µIU/mL. The patient has been feeling well and denies cold or heat intolerance, palpitations, diarrhea, neck pain, and skin/hair changes. The patient recalls being told that he has lumps in his thyroid. He has no family history of thyroid disease, is a nonsmoker, and takes only a daily aspirin. On today’s examination, a 2-cm nodule in the left lobe of the thyroid is palpated, but the rest of the thyroid does not appear enlarged or tender to palpation. The patient’s reflexes are within normal limits. There is no lid lag or signs of exophthalmos. Laboratory results obtained during this presentation reveal the following: TSH, 0.05 µIU/mL; free thyroxine (T4), 1.56 ng/dL (normal, 0.8-1.8 ng/dL); total T4, 9.3 µg/dL (normal, 4.5-12 g/dL); and total T3, 103 ng/dL (normal, 80- 181 ng/dL)..

2. What is this patient’s most likely diagnosis?

  1. Euthyroid sick syndrome
  2. Subacute thyroiditis
  3. Subclinical hyperthyroidism (SCH) from Graves’ disease
  4. SCH from a toxic adenoma
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3. What is the most appropriate next step in the management of this patient?

  1. Order a radioactive iodine uptake (RAIU) and scan
  2. Radioactive iodine to ablate the thyroid gland
  3. Reexamine the patient in 1 year
  4. Referral to a surgeon for total thyroidectomy
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Questions 4 and 5 refer to the following case.
A 38-year-old woman presents to the clinic with gradual-onset fatigue and weight gain. Two years ago, she was told that she had an enlarged thyroid. She has since relocated and has not seen a physician until now. The patient describes a 10-lb weight gain in the past year and states that her mother and aunt both have thyroid problems for which they take medication. The patient does not smoke and otherwise feels well. On examination, the only abnormal finding is a firm, nontender thyroid gland two-fold larger than normal. She has slightly delayed relaxation of her deep tendon reflexes. Initial laboratory results reveal the following: serum TSH, 18.3 IU/mL; serum free T4, 0.8 ng/dL; and serum thyroid peroxidase antibodies, 636 IU/mL (normal, < 10 IU/mL).

4. All of the following could explain this patient’s elevated serum TSH level EXCEPT
  1. Excess exogenous thyroid hormone
  2. Primary hypothyroidism
  3. Recovery from nonthyroidal illness
  4. Subacute thyroiditis
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5. The patient is diagnosed with Hashimoto’s thyroiditis and levothyroxine 125 µg daily is initiated. All of the following medications have been shown to interfere with the absorption of levothyroxine EXCEPT

  1. Aluminum hydroxide (antacids)
  2. Calcium carbonate
  3. Ferrous sulfate
  4. Potassium chloride
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Questions 6 and 7 refer to the following case.
A 35-year-old woman presents to the clinic with a 6-week history of palpitations, tremor, and nervousness. She states she has no medical problems, does not smoke, and denies taking any prescription medications. She reports a recent 7-lb weight loss, which she attributes to the herbal weight loss supplement she has been taking. On examination, the patient’s heart rate is 104 bpm, blood pressure is 124/68 mm Hg, and body mass index is 26 kg/m2. The patient clinically appears hyperthyroid and has an enlarged, very firm, nontender thyroid gland, no thyroid ophthalmopathy, and a tremor.

6. Which of the following is the best initial test to evaluate this patient’s hyperthyroidism?

  1. Serum total T3
  2. Serum total T4
  3. Serum TSH
  4. Thyroid-stimulating immunoglobulin
Click here to compare your answer.
7. A thyroid RAIU and scan is performed, which shows absent iodine uptake throughout the thyroid gland. A serum thyroglobulin level is undetectable. What is this patient’s most likely diagnosis?
  1. Exogenous thyrotoxicosis
  2. Graves’ disease
  3. Hashimoto’s thyroiditis
  4. Toxic multinodular goiter
Click here to compare your answer.
 

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