Test your medicine knowledge with the MKSAP challenge, in partnership with the American College of Physicians.

A 52-year-old man is evaluated for the sudden onset of erectile dysfunction that has persisted for 6 months. He reports having erections that are inadequate for vaginal penetration. He feels guilty about not being able to satisfy his wife’s requests for sexual intercourse, although he still has sexual desires. He has been sleeping poorly and feeling fatigued throughout the day. He reports no snoring or daytime somnolence, and his review of systems is otherwise negative. His wife does not report that the patient has episodes of nocturnal gasping or apnea. He has firm erections upon waking in the morning. For years, he has run 2 miles daily without chest pain or exercise-limiting dyspnea, although he has not been interested in exercise over recent weeks. Medical history is notable for hypertension. Family history is notable for his father who died of a myocardial infarction at age 70 years and his mother who died of complications from a stroke at the age of 94 years. He has never smoked cigarettes. His 10-year risk of atherosclerotic cardiovascular disease is calculated to be 5% using the Pooled Cohort Equations. Medications are hydrochlorothiazide and lisinopril. He has taken these medications for 6 years without interruption.

On physical examination, the patient is afebrile, and blood pressure is 132/64 mm Hg. BMI is 26. Heart, lung, and abdominal examinations are normal. The penis is uncircumcised without abnormalities, and the testes are normal size.

Laboratory studies show a fasting plasma glucose level of 98 mg/dL (5.4 mmol/L).

Which of the following is the most likely cause of this patient’s erectile dysfunction?

A. Hypogonadism
B. Mood disorder
C. Obstructive sleep apnea
D. Prolactinoma

MKSAP Answer and Critique

The correct answer is B: Mood disorder.

This patient has erectile dysfunction (ED) secondary to a mood disorder, most likely major depressive disorder. Characteristic features of inorganic (psychological) ED are sudden onset of symptoms and persistence of nocturnal or morning erections, which indicates that the anatomic and physiologic mechanisms for erection are intact. This patient has guilt, low energy, and decreased interest, all of which are symptoms of depression. Patients with inorganic ED can be reassured that their condition is likely to resolve with time and effective treatment of their mood disorder.

This middle-aged man is not likely to have hypogonadism. His testicles are of normal volume, and he reports continued sexual desires. One of the earliest symptoms of hypogonadism is substantial reduction or absence of sexual thoughts.

This patient has poor sleep; however, he is not overweight and reports no snoring, gasping, apnea, or daytime somnolence. Depression is the most likely cause for this patient’s fatigue, given his guilt, anhedonia, and inorganic ED.

Although an early sign of prolactinoma is ED, the persistence of nocturnal and morning erections in this patient makes an organic cause unlikely. Additionally, he lacks other symptoms of prolactinoma, such as headache, visual changes, or decreased body and facial hair.

Key Point

• Characteristic features of inorganic erectile dysfunction are sudden onset of symptoms and persistence of nocturnal or morning erections.

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