A 66-year-old man has become increasingly short-tempered with his wife. He has diarrhea, weight loss, and weakness in the proximal muscles. He has atrial fibrillation and tachycardia. Which of the following is the most likely diagnosis?
Congestive heart failure
Cushing syndrome
Hyperthyroidism
Mitral valve prolapse
Pheochromocytoma
Correct answer
Hyperthyroidism
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correct answer: C
Hyperthyroidism (choice C) is often due to excessive production of thyroid hormone in the absence of TSH stimulation. Classic symptoms include irritability, nervousness, weight loss, increased appetite, tremor, sweating, and tachycardia.
Congestive heart failure (choice A) is a condition where decreased cardiac output causes inadequate perfusion of tissues. It does not cause irritability.
Cushing syndrome (choice B) is any condition that causes excess serum cortisol. Signs and symptoms include weight gain, round face, thinning of skin, purple striae, and hirsutism.
Mitral valve prolapse (choice D) is a condition where the mitral valve bulges into the left atrium during systole. It would not cause this man’s clinical presentation.
Pheochromocytoma (choice E) is a tumor of the adrenal medulla that causes excess secretion of catecholamines, such as epinephrine and norepinephrine.