11th April 2024

Erectile Dysfunction

Erectile dysfunction is a common problem defined as a persistent inability to attain and maintain an erection sufficient to permit satisfactory sexual performance. The incidence increases with age such that up to 50% of men will experience ED at ≥80 years. Its causes are broad (see Table 1) and can be best categorised into organic, psychogenic or mixed. Organic causes tend to present with a sub-acute or chronic onset, whereas psychogenic causes are often sudden or intermittent.

Table 1. Causes of erectile dysfunction.

In addition to age, the factors associated with ED include cardiovascular disease, diabetes mellitus, dyslipidaemia, smoking and medication. As a result, the most common causes are vascular and drug-related, and ED is often a sign of peripheral or cardiovascular disease.

Investigations

The focus of investigations is on determining cardiac risk, associated metabolic syndromes and hormonal dysfunction. Blood tests should include: HbA1c, lipid profile, LFTs, TFTs, total testosterone and U&Es. Total testosterone should be performed as a fasting morning sample and repeated alongside FSH, LH, prolactin and sex hormone-binding globulin if found to be low. An ECG should be performed. If LUTS are present, a PSA should be considered.

Management

Lifestyle modification, including weight loss, smoking cessation, alcohol reduction and regular exercise, should be considered. Any associated cardiovascular (e.g. HTN) or metabolic (e.g. diabetes mellitus) conditions should be optimised. If a drug cause is suspected, a trial suspension can be considered (although most men benefit more from a PDE-5 inhibitor than drug suspension).

For all men not at high cardiac risk from sexual activity, a PDE-5 inhibitor such as sildenafil or tadalafil should be considered regardless of cause. PDE-5 inhibitors increase cyclic GMP in the corpus cavernosum through competitive inhibition of PDE-5, which results in nitric oxide-induced vasodilation. Onset is 30 – 60 minutes and the duration is 4 – 5 hours (up to 12 hours in some). Contraindications include a recent history of myocardial infarction, unstable angina or stroke, or retinitis pigmentosa. Profound hypotension can occur if co-administered with other vasodilators or anti-hypertensives. Common side effects include facial flushing, headaches, dizziness and short-term, blue-tinged vision. All men at high cardiac risk should be referred to Cardiology for assessment.