What are the causes of leg edema?

Causes of Leg Edema

Leg edema results from an imbalance in fluid filtration between capillary and interstitial spaces, with multiple potential causes ranging from systemic conditions to localized pathology. 1, 2

Systemic Causes

Cardiac Causes

• Heart failure is a common cause of bilateral leg edema due to increased central venous hypertension 1
• Heart failure leads to increased capillary permeability and plasma volume, resulting in fluid accumulation 3, 1
• Decreased arteriovenous pressure gradient reduces renal perfusion pressure, contributing to fluid retention 3
• Both systolic and diastolic heart failure (heart failure with preserved ejection fraction) can cause pitting edema 1

Hepatic Causes

• Liver cirrhosis decreases protein synthesis, leading to reduced plasma oncotic pressure 1, 4
• Portal hypertension in cirrhosis contributes to increased systemic venous pressure 1, 5
• Ascites often accompanies leg edema in advanced liver disease 2

Renal Causes

• Kidney disorders cause protein loss (nephrotic syndrome), decreasing plasma oncotic pressure 1, 6
• Sodium and water retention from renal dysfunction increases plasma volume 1, 5
• Chronic kidney disease impairs the kidney's ability to regulate fluid balance 5

Medication-Induced Causes

• Calcium channel blockers can cause peripheral edema through vasodilation 1, 2
• Thiazolidinediones (TZDs) cause fluid retention and edema 3
• NSAIDs can contribute to edema by promoting sodium retention 7, 8
• Corticosteroids cause sodium retention with resultant edema 8

Localized Causes

Venous Disorders

• Chronic venous insufficiency is characterized by peripheral edema, often with skin changes and hyperpigmentation 1, 9
• Post-thrombotic syndrome following deep vein thrombosis (DVT) leads to chronic edema 1, 9
• Venous obstruction from DVT causes unilateral swelling 3, 6

Lymphatic Disorders

• Lymphedema occurs when protein-rich fluid accumulates in the interstitium due to impaired lymphatic drainage 2, 4
• Primary lymphedema is due to congenital abnormalities of the lymphatic system 6
• Secondary lymphedema results from damage to lymphatic vessels (surgery, radiation, infection, malignancy) 6

Distinguishing Features

Distribution Pattern

• Bilateral symmetric edema typically suggests systemic causes (cardiac, renal, hepatic) 1, 7
• Unilateral or asymmetric edema more commonly indicates localized pathology (venous thrombosis, compression) 1, 9

Timing and Progression

• Edema that worsens throughout the day and improves with elevation suggests venous insufficiency 1
• Morning edema may indicate other causes such as renal or cardiac disease 1

Associated Symptoms

• Dyspnea, orthopnea, or paroxysmal nocturnal dyspnea suggests heart failure 3, 1
• Skin changes like hyperpigmentation, lipodermatosclerosis, or ulceration suggest chronic venous insufficiency 1, 9
• Jugular venous distention and pulmonary rales point toward heart failure 3, 1

Special Considerations

Idiopathic Edema

• Idiopathic cyclic edema occurs predominantly in women 4, 6
• Can lead to chronic diuretic abuse, which paradoxically worsens edema 4

Rare Causes

• Myxedema from hypothyroidism 9
• Lipedema (abnormal fat deposition) 6
• Vascular anomalies and tumors 6

Diagnostic Approach

• Evaluate for bilateral vs. unilateral presentation to distinguish between systemic and local causes 1, 7
• Assess for associated symptoms that suggest specific etiologies 1, 9
• Look for skin changes that might indicate chronic venous insufficiency 1
• Consider medication review to identify potential iatrogenic causes 3, 8
• Evaluate cardiac, renal, and hepatic function in bilateral edema 1, 5

Understanding the underlying cause of leg edema is essential for appropriate management, which may include treating the primary condition, sodium restriction, diuretics, compression therapy, or specific interventions based on etiology 2, 5.