A 55-year-old man comes to the office due to the sudden onset 4 months ago of inability to maintain a firm erection. He is still interested in sex but feels guilty that he is disappointing his wife and ruining his marriage. The patient awakens with a normal erection but cannot maintain it to engage in intercourse. He has intermittent knee pain, decreased appetite, constipation, insomnia, and low energy. The patient has a history of hypercholesterolemia, hypertension, and type 2 diabetes mellitus. Medications include aspirin, metformin, atorvastatin, and lisinopril, which he has taken for the past 5 years. He denies any alcohol or substance abuse, except for smoking a pack of cigarettes daily for 20 years, which he stopped 5 years ago.
Temperature is 36.7 C (98.1 F) , blood pressure is 130/80 mm Hg, pulse is 70/min, and respirations are 16/min. BMI is 28 kg/m². Physical examination is normal. No hepatomegaly is present. The penis and testes appear normal, and there are no palpable masses. Neurologic examination is within normal limits.
Complete blood count and chemistries are normal. Hemoglobin A1c is 7.3%. TSH is 3 µU/mL, alanine aminotransferase is 24 U/L, and aspartate aminotransferase is 37 U/L.
Which of the following is the most likely cause of this patient's erectile dysfunction?

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11ec193a_98c1_fbdc_853d_ab2e63c9e428_MD0002_00 Sudden onset of erectile dysfunction (ED) while continuing to have intact early morning erections suggests a psychogenic ("inorganic") etiology, in this case a mood disorder (characterized by depressive symptoms, including impaired sleep, poor appetite, low energy, and guilt). Nocturnal erections, which occur during periods of rapid eye movement (REM) sleep, often continue in a patient with psychogenic ED. However, in severely depressed men, who may no longer experience REM sleep, nocturnal and early morning erections may also be absent. Organic ED is typically slowly progressive and can be due to multiple causes (eg, diabetes, cardiovascular disease, hypertension, obesity, low testosterone, hyperprolactinemia, thyroid dysfunction, smoking). However, this patient's continued ability to have early morning erections indicates that his erectile dysfunction is not due to any anatomic or physiologic causes, such as diabetes or vascular disease (Choices A and E). Medications that may cause ED include serotonergic antidepressants, spironolactone, clonidine, and thiazide diuretics. Use of illicit substances and alcohol are also associated with ED. (Choice B) Hypogonadism is characterized by small testes and reduced interest in sex, neither of which is present in this patient. Also, ED associated with hypogonadism (ie, low testosterone) would not be consistent with early morning erections. (Choice C) Medication adverse effects are an unlikely explanation of this patient's sudden-onset ED 4 months ago and his intact early morning erections. Among antihypertensives, thiazide diuretics and beta blockers are most commonly associated with ED. ACE inhibitors are less likely and metformin and statins are uncommon causes. Educational objective: Erectile dysfunction can be due to multiple etiologies, including vascular, neurologic, hormonal, and psychological abnormalities. Psychogenic causes should be suspected if erectile dysfunction has a sudden onset and the patient is able to have early morning and nocturnal erections during REM sleep. __________ References: Erectile dysfunction. (http://www.ncbi.nlm.nih.gov/pubmed/23040455)

A 55-Year-Old Man Comes to the Office Due to the Sudden