Drugs esp. excess alcohol
Diabetes (autonomic dysfunction)
Serious disorders not to be missed
Chronic kidney disease
Excessive cigarette smoking
Iatrogenic e.g. prostate surgery, drugs
Thrombosis corpus callosum
Depression including drugs
Thyroid/other endocrine: several (see history)
Spinal dysfunction e.g. spinal cord pathology, cauda equina lesion
Is the patient trying to tell me something?
Consider psychosexual dysfunction incl. marital disharmony, performance anxiety
Nature of onset including nature of sexual relationship
Ask about nocturnal and early morning erections
Drug history incl. alcohol, nicotine (4 times risk), street drugs (cocaine, cannabis), pharmaceutical agents esp. antihypertensives (beta blockers, diuretics), hypolipidaemic agents, antiandrogens (prostate cancer treatment), antidepressants, antipsychotics, H2-receptor antagonists
Genitourinary, cardiovascular and neurogenic examinations are important. This should include a rectal examination; examination of the vascular and neurological status of the lower limbs; and genitalia esp. the testicles and penis. Check the cremasteric and bulbocavernosus reflexes.
Endocrine causes to consider include androgen/testosterone deficiency, hyperprolactinaemia and hypothyroidism. Consider pituitary fossa tumour.