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CASE 10.1

A 27-year-old female presents to the office with the chief complaint of chronic fatigue for 4 months. She has gained 17 lb in 3 months, despite a decreased appetite. She also complains of depression, increased sleep, lack of energy, hair loss, and cold intolerance. Her past medical history is unremarkable, and she takes no medications. She has never had any surgeries.

Question 10.1.1 Which of the following physical examination findings would be expected?

A) Tachycardia

B) Exophthalmos

C) Fine tremor

D) Peripheral sensory loss

E) Delayed relaxation in reflexes

Answer 10.1.1 The correct answer is "E." The history given is consistent with a hypothyroid state. Symptoms of hypothyroidism include thinning hair, dry skin, a hoarse and deep voice, bradycardia, and a prolonged relaxation in the reflexes. Tachycardia and a fine tremor are more typical of hyperthyroidism, and exophthalmos is characteristic of Graves' disease (one specific cause of hyperthyroidism). Proximal muscle weakness may occur in hypothyroidism, but sensory loss is not typical (although hypothyroidism, diabetes, gout, rheumatoid arthritis, obesity, and connective tissue disorders can contribute to carpal tunnel syndrome which may be the initial presenting symptom of these diseases).

Question 10.1.2 How can the diagnosis of hypothyroidism best be confirmed?

A) Elevated thyroid-stimulating hormone (TSH) level

B) Low TSH level

C) Thyroid biopsy

D) Radionuclide scan

E) Serum thyroglobulin

Answer 10.1.2 The correct answer is "A." The TSH is the most sensitive test for both hypo- and hyperthyroidism, and changes in the TSH can precede abnormalities in serum thyroxine (best measured as free T4) level. An elevated TSH occurs when the pituitary detects insufficient thyroid hormone production (low free thyroxine), and TSH production is shut off when the pituitary detects an excess of thyroid hormone circulating (elevated free thyroxine). With pituitary dysfunction, there is insufficient TSH production resulting in a low TSH and decreased free thyroxine (T4) production without feedback of an elevated TSH—the pituitary just doesn't do its job (such a slacker!). In order to discern between thyroid gland dysfunction (more common) and pituitary dysfunction (most often secondary to a pituitary adenoma), it is necessary to obtain a free T4 in conjunction with the TSH level. Since pituitary disorders are rare, and often suggested by other clues in the history and physical, TSH alone is usually sufficient for initial screening for thyroid disease. "C," a biopsy, is used to evaluate thyroid masses and nodules. A radionuclide ...

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