Erectile dysfunction in the primary sector

Erectile dysfunction (ED) is the inability to obtain or maintain an erection sufficient for penetration and/or satisfactory sexual activity (NIH, 1993). It is a dysfunction secondary to a primary cause, which may be either psychological (psychogenic ED) or physical (organic ED). In many instances, it is a combination of both.

Embarrassment and lack of knowledge about treatment options may contribute to a low treatment rate. It is estimated that at least 50% of men with diabetes of age 40–70 years develop ED at some stage. By the age of 70 years, this figure has increased to almost 70% (Kelleher and Oxenham, 1993).

Diabetes and ED
A broad range of conditions can contribute to ED, e.g. diabetes mellitus, vascular disease, surgery, traumatic injury, and low testosterone levels. Diabetes constitutes 40% of all primary physical causes of ED (Zonszein, 1995).

Assessment and diagnosis
Initial discussions should establish that there is a genuine failure to achieve an erection – other sexual problems may require a different approach. Examination of the man’s genitalia (penis size, testes size and consistency) should be carried out. Testosterone, follicle-stimulating hormone, luteinizing hormone (LH) and prolactin levels should be measured routinely in men with a lack of libido, previous inguinal or scrotal surgery, or small testicles. Testosterone should not be too low; LH and prolactin should not be too high. Men with primary hypogonadism causing low concentrations of testosterone will have high levels of LH because of reduced negative feedback (Jeffcoate, 1995). Although rare, endocrine causes are easily excluded.

Good nerve supply and patent blood circulation are required for an erection to occur. The vascular network of the penis and surrounding tissue is essential to normal erectile function.

If ED is caused by vascular or neurological disease, hormone levels should be normal. Abnormal Doppler studies would tend to confirm a vascular cause; abnormalities in basic neurological tests or nerve conduction studies would generally indicate a neurological cause.

Diabetes complications can affect both the blood and nervous supply to the penis. The vascular and neurological components of diabetes make it the single most common systemic disorder associated with ED (Kelleher and Oxenham, 1993). The development of ED associated with diabetes is insidious, occurring over a period of months to years. Patients describe diminished rigidity and reduced ability to sustain an erection. They usually complain of absence of early morning erections, although libido remains intact.

Addressing diabetes complications
Reducing long-term complications of diabetes is an ongoing challenge. One of the most important factors that can be addressed is glycaemic control. Good control may be achieved with diet and/or oral therapy – if these measures fail, insulin therapy may be commenced. It has been shown that improving glycaemic control can prevent further complications and reduce existing ones (DCCT, 1993; UK PDS, 1998a,b).

In men with diabetes, the raised carbohydrate state may lead to angiopathy, a condition characterised by thickening of the basement membrances of capillaries. Disease involving the network of small vessels in the body of the penis may result in decreased erectile capacity. Macrovascular damage could compromise the erectile function severely. This may be caused by the generalised process of atherosclerosis, especially atheroma of the pudendal or iliac arteries. Risk factors of atherosclerosis include hypercholesterolaemia, cigarette smoking and hypertension (Close and Ryder, 1993).

Psychological reasons
Psychological issues should not be ruled out simply because a man has diabetes. Although ED does not affect life expectancy, it can have a strong negative effect on wellbeing and quality of life. It also often affects interaction with family and associates. The problem tends to be compounded by unrealistic expectations of continuing sexual prowess, partly as a result of most men’s reluctance to admit to or even discuss the problem with their peers.

Drug side-effects
A reduction in erections can often be attributed to blood pressure medication such as diuretics, β-blockers, and calcium channel blockers (all have been well documented as causing ED). Other classes of drugs that can give rise to ED include lipid-lowering drugs such as fibrates and anti- depressants. It is therefore apparent that a thorough assessment of prescribed medications should be carried out (Mersdorf et al, 1991; Grimm and Grandits, 1997).

If a drug is believed to be causing ED, it should be changed wherever possible. This may entail referral back to the doctor who commenced treatment.

Treatment options
Once the diagnosis has been made, including aetiology, appropriate treatment can be given. Table 1 gives characteristics of organic ED and psychogenic ED.

In the past few years, there have been significant advances in the treatment of ED such that the majority of men can now be effectively treated. Simple lifestyle changes such as giving up smoking, reducing alcohol consumption and trying to reduce stress and anxiety can help (Williams and Pickup, 1999).

Sex therapy
If the main cause of a man’s ED is considered to be either psychological or due to difficulties in his relationship with his partner, a course of sex therapy is recommended . This can also be initiated in combination with other forms of drug or device treatments as it is very useful in helping couples to re-establish a sexual relationship where there has been a lengthy period without sexual activity because of the ED.

Referral to a sexual counsellor should be discussed in all cases, even when the main cause is organic, as there may be a psychological overlay.

Vacuum constriction devices
Vacuum constriction devices are one of the most commonly used treatments. The devices are often used by men who fail to respond to drug therapy, or decide against it. Vacuum constriction devices are particularly useful for organic ED.

The device consists of a plastic cylinder attached to a pump, which may be hand or battery driven, and one or more tension rings. The plastic cylinder is placed over the penis. As air is pumped out of the cylinder, a vacuum is created and blood enters the penis. When the penis is rigid, a ring is slipped off the cylinder to encircle the base of the penis, thus trapping the blood and maintaining the erection.

Pharmacological therapy
Sildenafil was the first oral treatment for ED to be licensed in the UK. Under current guidelines (DoH, 1999), diabetes is one of the conditions for which sildenafil can be provided on an FP10 prescription. The mode of action involves relaxation of blood vessels in the penis. Taken about an hour before anticipated sexual activity, it helps a man to achieve an erection in response to sexual stimulation.

Intracavernosal and transurethral therapy are non-oral pharmacological therapies. In intracavernosal therapy, alprostadil is injected directly into the penis through a very fine needle. This usually brings about the normal changes in the penis that occur during an erection. The technique can be easily learnt for home use.

Transurethral therapy entails the introduction of a small pellet of alprostadil into the urethra with a special disposable applicator. It is equally effective for all patients with organic ED, although recent studies have shown a reduced success rate with organic causes such as diabetes (Padma et al, 1997).

Hormone treatment
Only a small proportion of cases are caused by hormone abnormalities. Of these, the most frequent hormone abnormality is a reduced level of testosterone which can be restored by appropriate testosterone replacement.

Conclusion
Improved understanding of the causes of ED has led to a dramatic increase in the research and development of drugs and devices to treat the condition. As a result, a wider choice of therapies has become available.

Medical reasons and personal preference will guide the choice of therapy. ED affects not only the man but also his partner and what is suitable for one patient/couple may not be recommended or chosen by another. However, the current range of therapeutic options should help to relieve the burden of ED.

Education module No. 5: erectile dysfunction in the primary sector

Section 1. List the signs and symptoms, advice to be given, investigations and referrals for the aetiologies of erectile dysfunction listed below:

• Vascular disease
• Neurological
• Drug interactions
• Psychological

Section 2. This overview above is provided for readers wishing to refresh their knowledge of erectile dysfunction in people with diabetes. Reading of this section may be deferred until after completion of the remainder of the module.

Section 3. Case studies

Case study 1
Brian, 68 years old, obese (BMI=34), with type 2 diabetes of 8 years duration. Diabetes control is poor (HbA_1c of 8.9%). He has had gradual onset of failing erections for 3 years. However, he has a strong libido. Brian is in a stable relationship with a physically healthy woman. He is also under the care of the foot clinic for a neuropathic foot ulcer.

Questions about case study 1

• a) What are the key factors to take into account?
• b) What would you expect to find on clinical examination and investigation? 
• c) What therapeutic approach would you take?

Case study 2
Matthew, 50 years old, has diabetes of 10 years duration treated with maximum oral therapy. His HbA_1c is 8%. He has hypertension and, for many years, has been complaining of gradual progression of erectile dysfunction. He takes a multitude of drugs to try to keep the hypertension under control. For the past 6 months, Matthew has been prescribed antidepressants.

Questions about case study 2

• a) What are the key factors to take into account?
• b) What would you expect to find on clinical examination and investigation? 
• c) What therapeutic approach would you take?

Case study 3
Troy is a 33 year old stressed manager of an international company. He has had type 1 diabetes for 12 years. His HbA_1c is 7.4%. He is taking mild sedatives. Since his divorce 4 years ago, Troy has had an active sexual life with several women. He has a new partner and is finding it difficult to maintain his erections, although he can still achieve spontaneous erections, e.g. on awakening or while asleep. Troy has 30 units of alcohol at the weekends and smokes about 10 cigarettes per day.

Questions about case study 3

• a) What are the key factors to take into account?
• b) What would you expect to find on clinical examination and investigation? 
• c) What therapeutic approach would you take?

Section 4. Think of five patients with type 1 and type 2 diabetes who you see in your practice, and answer the questions below for each:

• a) Do you think that this patient is at risk of developing erectile dysfunction?
• b) What factors indicate their risk?
• c) What is the underlying aetiology?
• d) What advice will you give?
• e) Who else may need to be involved?

Section 5. After completing the above exercise, identify two or three key points, stating how this will influence your future practice.