What are the causes of leg oedema in different age groups and patient populations?

Causes of Leg Edema

Leg edema results from either systemic conditions causing bilateral swelling (heart failure, kidney disease, liver disease, medications) or localized pathology causing unilateral swelling (venous insufficiency, deep vein thrombosis, lymphedema). 1, 2

Systemic Causes (Typically Bilateral)

Cardiac

• Heart failure is the leading systemic cause, resulting from increased central venous hypertension, increased capillary permeability, and plasma volume expansion 1, 2
• Both biventricular failure and heart failure with preserved ejection fraction can produce pitting edema 1
• Associated symptoms include dyspnea, orthopnea, paroxysmal nocturnal dyspnea, and physical findings of jugular venous distention, pulmonary rales, hepatojugular reflux, and S3 gallop 1, 2

Renal

• Kidney disorders (particularly nephrotic syndrome) cause increased protein loss, decreased plasma oncotic pressure, and sodium/water retention 2, 3
• Results in bilateral pitting edema 2

Hepatic

• Liver cirrhosis and hepatic disorders decrease protein synthesis, leading to decreased plasma oncotic pressure and increased systemic venous hypertension 2, 3
• Produces bilateral pitting edema 2

Medication-Induced

• Calcium channel blockers (especially dihydropyridines) are the leading pharmaceutical cause, more common in women, causing edema through increased capillary permeability 4, 2
• NSAIDs cause edema through increased capillary permeability, sodium/water retention, and renal dysfunction 2
• Thiazolidinediones (TZDs) cause fluid retention, particularly when combined with insulin 4, 2
• Vasodilators and other antihypertensive medications can contribute 2, 5

Localized Causes (Typically Unilateral or Asymmetric)

Venous

• Chronic venous insufficiency is the most common cause in older patients, characterized by peripheral edema with hyperpigmentation, lipodermatosclerosis, and skin changes 1, 2, 5
• Edema typically worsens with prolonged standing and improves with elevation 1
• Deep vein thrombosis causes acute unilateral edema that may become chronic (post-thrombotic syndrome) 2, 3

Lymphatic

• Lymphedema presents as brawny, nonpitting edema 6
• Secondary causes include tumor, trauma, previous pelvic surgery, inguinal lymphadenectomy, and previous radiation therapy 6

Other Localized Causes

• Pelvic tumors causing venous or lymphatic compression 7
• Infection or trauma 7
• Arterial causes (pain in supine position or after revascularization) 8

Critical Distinguishing Features

Distribution Pattern

• Bilateral symmetric edema indicates systemic causes (cardiac, renal, hepatic disorders, medications) 1, 3
• Unilateral or asymmetric edema indicates localized pathology (venous thrombosis, compression, lymphedema) 1, 3

Timing

• Worsening in the evening suggests venous insufficiency 1, 3
• Worsening in the morning suggests other systemic causes 1

Edema Characteristics

• Pitting edema: cardiac, renal, hepatic, venous, medication-induced 1, 2
• Non-pitting edema: lymphedema 6

Diagnostic Algorithm

Step 1: Determine Distribution

• Assess whether edema is bilateral or unilateral 3
• Bilateral edema directs evaluation toward systemic causes 1
• Unilateral edema directs evaluation toward localized pathology 1

Step 2: Physical Examination

• Evaluate for jugular venous distention, pulmonary rales, hepatojugular reflux, and S3 gallop (suggests heart failure) 1, 3
• Assess for pitting versus non-pitting edema 3
• Look for skin changes: hyperpigmentation, lipodermatosclerosis, or ulceration (suggests chronic venous insufficiency) 1, 3
• Examine for signs of liver disease or renal disease 1

Step 3: Medication Review

• Review all medications for potential causative agents (calcium channel blockers, NSAIDs, TZDs, vasodilators) 2, 3
• Consider discontinuation or dose adjustment if medication-induced edema is suspected 3

Step 4: Laboratory and Imaging Evaluation

• BNP/NT-proBNP to confirm or exclude heart failure 1, 3
• Liver function tests and renal function tests to evaluate for systemic diseases 3
• Urinalysis to assess for proteinuria (nephrotic syndrome) 5
• Ankle-brachial index (ABI) to evaluate for peripheral arterial disease 3
• Duplex ultrasonography if deep venous thrombosis is suspected 6

Common Pitfalls

• Do not assume bilateral edema is always cardiac without investigating other systemic causes (renal, hepatic, medications) 3
• Avoid empiric diuretic therapy without determining the underlying cause, especially in older patients where long-term diuretic use can lead to severe electrolyte imbalances, volume depletion, and falls 5
• Bilateral venous insufficiency is uncommon; when bilateral edema occurs, investigate systemic causes first 1
• In older patients with multiple comorbidities, the cause is often multifactorial 5
• Do not overlook medication-induced edema, particularly in patients on calcium channel blockers 4, 2