Erectile dysfunction (ED) is the persistent inability to attain and/or maintain an effective erection. The prevalence of ED is high, with one UK study estimating a prevalence of 26 per cent and a lifetime risk of 39 per cent.
Successful erections require interactions between psychological, vascular, neurological and hormonal factors.
ED has traditionally been split into psychogenic and organic categories but up to 80 per cent of cases are thought to have an organic cause. ED is strongly associated with diabetes and cardiovascular disease (CVD).
A detailed history of the sexual problem is important for diagnosis. This should include the duration of symptoms, the circumstances in which ED occurs, whether the patient has nocturnal erections, and whether they have other sexual problems such as premature ejaculation or low libido.
A history of their social situation and a partner history can provide valuable information about a possible trigger, such as job loss or other life event. In addition, the patient's understanding of sexual anatomy and function should be explored.
The patient's medical history may reveal predisposing factors such as diabetes, CVD, neurological or endocrine disease. Pelvic or spinal surgery and radiotherapy can also lead to the development of ED.
In about 25 per cent of cases, ED is triggered by medication. Drugs associated with ED include antihypertensives and antidepressants (see box). It can also be caused by smoking, alcohol and opiate use.
A general examination of the patient should be carried out including examination of the cardiovascular, neurological and endocrine systems.
The penis should be examined for conditions such as phimosis, hypospadias and plaques that indicate Peyronie's disease.
The testicles should be examined for size. Abnormalities of beard, body hair or voice may indicate hypogonadism.
A digital rectal examination of the prostate should be carried out if there is any history of lower urinary tract symptoms.
Further investigations may be carried out to identify the aetiology of the condition. In addition, screening for diseases associated with ED including CVD and diabetes should be carried out.
Laboratory tests include FBC, U&Es, fasting blood glucose, lipid profile, TFTs and urinalysis should be done.
Serum testosterone (ideally free testosterone) should be measured in the morning as there is a diurnal variation. If the initial test is abnormal, follicle-stimulating hormone, luteinising hormone and prolactin levels should be measured. Other specialist investigations may be required in a few difficult cases.
First-line management is through lifestyle change. Stopping smoking, reducing alcohol intake, increasing exercise and improving diet can improve ED and tackle associated cardiovascular risks.
If the ED is the result of an underlying condition, treatment of that disease may be the priority.
Where a psychological cause is identified, psychosexual therapy with or without relationship counselling may be the only treatment required. Even when the cause is organic, education and counselling may be a useful adjunct to treatment.
If the ED is the result of medication, a change in treatment should be considered. ACE inhibitors, angiotensin receptor blockers and calcium channel blockers are less likely to cause ED than other antihypertensives.
The first-line drug treatment for most ED patients is with a PDE5 inhibitor. These include sildenafil, tadalafil and vardenafil. These cannot be taken by patients using nitrate drugs, including glyceryl trinitrate and isosorbide.
Patients should be advised that erection will only occur with adequate sexual stimulation. Success rates are good (up to 75 per cent) although patients with diabetes and those who have had a radical prostatectomy do less well.
If after at least four attempts a patient has not responded to the highest dose of at least two PDE5 drugs then they should be considered to be non-responders.
Testosterone replacement is an option if the patient has low testosterone levels, but is ineffective if their level is normal.
Second-line drug treatments include intracavernosal injection of alprostadil. There is also an intra-urethral pellet form of alprostadil available, although this is less effective than injection.
Non-drug treatment options include vacuum devices and penile prostheses. NHS prescriptions for ED treatment are only available to patients with certain conditions (see box) or who are suffering high levels of distress because of impotence.
Dr Spinks is a GP in Strood, Kent
Key Points on erectile dysfunction
- ED has a high prevalence.
- Up to 80 per cent of cases have an organic cause.
- 25 per cent may be due to medication.
- Sudden onset in younger patients with recent social/relationship upheaval is likely to be psychogenic.
- History, examination and investigations should look for associated conditions such as CVD.
- Lifestyle advice and education about anatomy and sexual function should be given to all patients.
- First-line medications are the PDE5 inhibitors but they are contraindicated in patients on nitrates.
- Second-line therapies include intracavernosal injections, urethral pellets, vacuum devices and penile implants.
- NHS prescriptions of ED treatments are currently restricted.
Drugs associated with ED
- Hormonal treatments
- H2 blockers
NHS treatment for ED is available to patients with
- Multiple sclerosis
- Parkinson's disease
- Prostate cancer
- Radical pelvic surgery
- Renal failure
- Severe pelvic injury
- Single gene neurological disease
- Spina bifida
- British Society for Sexual Medicine Guidelines on the Management of Erectile Dysfunction 2007: www.bssm.org.uk
- Brosman S A, Erectile Dysfunction, e.medicine: www.emedicine.com/med/topic3023.htm
- Miller T A, Diagnostic evaluation of erectile dysfunction Am Fam Physician. 2000; 61: 95-104, 109-10.