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Chapter 44. Thyroid Disorders

Student Questions

The best test/approach for diagnosing this patient for hypothyroidism is:

A 54-year-old 60 kg (132 lb) woman presents to your pharmacy complaining of several months of fatigue, dry skin, constipation, and feeling cold.

A. Physical examination of the skin, abdomen, and thyroid gland

B. Serum T3 and T4 levels

C. Serum TSH (thyrotropin) level and FT4 (free thyroxine)

D. Serum anti-TPOAb (antithyroid peroxidase enzyme)

Answer: C

Option A: Incorrect. While physical examination of selected systems assists in the diagnosis of thyroid disease, the related findings do not specifically correlate with thyroid dysfunction. Furthermore, examination of the thyroid gland can detect enlargement or nodules yet such findings do not correlate with thyroid function.

Option B: Incorrect. Levels of free T3 and/or T4 will be decreased in patients with overt thyroid disease. However, patients with mild ("subclinical") or early hypothyroidism may have serum hormone levels within the reference range.

Option C: Correct. TSH is the gold standard test for screening, diagnosing, and monitoring patients for both hypo- and hyperthyroidism. Since the patient is symptomatic, many clinicians would also order a FT4 to further confirm a diagnosis of hypothyroidism.

Option D: Incorrect. While some patients with hypothyroidism have positive anti-TPOAb levels, not all patients with positive antibody tests are hypothyroid.

If the patient is hypothyroid and therapy is warranted, which medication is most appropriate?

A 54-year-old 60 kg (132 lb) woman presents to your pharmacy complaining of several months of fatigue, dry skin, constipation, and feeling cold.

A. Liothyronine (LT3)

B. Levothyroxine (LT4)

C. T3 and T4 combination therapy

D. Dessicated thyroid extract (DTE)

Answer: B

Option A: Incorrect. Due to its short half-life T3 therapy often is associated with adverse effects, and its use as monotherapy is not physiologic.

Option B: Correct. In almost all patients LT4 is the therapy of choice for hypothyroidism.

Option C: Incorrect. Therapy with combined T3 and T4 is not associated with improved outcomes compared to LT4 monotherapy.

Option D: Incorrect. DTE has both T3 and T4 in a ratio that is unphysiologic for humans. Use of DTE shows no outcome benefit compared to LT4 monotherapy.

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