# Three routes to edema

Heart, kidney, and liver: similar swelling, different mechanisms

Andrew Bland, MD, FACP, FAAP · October 19, 2026

[Open visual and zoom](https://urinenephrology.org/visual-reference/case-edema-heart-kidney-liver.html)

Heart failure: venous congestion impairs sodium excretion. Nephrotic syndrome: albumin loss and renal sodium retention contribute to edema. Cirrhosis: splanchnic vasodilation reduces effective arterial filling and activates sodium and water retention. These processes can overlap.

## Connect this to the edema lecture

[Edema: The Circulation Cycle Approach — follow the full fluid-return pathway](https://urinenephrology.org/2025_UDPA_Lectures_Live/edema/index.html#circulation-pathway)

**Leg interstitial fluid → lymphatic drainage → venous circulation → right heart → lungs → left heart → renal arteries → kidneys → urine.**

Lymphatic drainage rejoins the central veins in the upper chest. Alongside this, trace leg venous blood through the thigh veins and inferior vena cava (IVC) to the right heart.

Use the circulation pathway to ask where fluid return, effective arterial filling, or renal sodium excretion is impaired. Heart failure adds venous congestion and sometimes reduced forward flow; nephrotic syndrome alters oncotic forces and sodium handling; cirrhosis combines portal hypertension, vasodilation, and retention.

**Clinical connection:** Persistent edema does not guarantee adequate renal perfusion. Read the creatinine trend with congestion, blood pressure, urine output, and response to treatment.

## Heart failure and congestion

High renal venous pressure can impair kidney function. Reduced effective arterial filling may also activate RAAS and ADH. Read the creatinine trend with the JVP, weight, blood pressure, urine output, and response to decongestion; a rise alone does not establish volume depletion.

## Nephrotic syndrome and edema

Urinary albumin loss lowers plasma oncotic pressure, while renal sodium retention also contributes. Intravascular volume varies. Heavy proteinuria and low serum albumin help explain swelling that might otherwise be labeled heart failure.

## Cirrhosis and arterial filling

Portal hypertension and splanchnic vasodilation can produce low effective arterial filling despite ascites and edema. RAAS and ADH promote retention; disproportionate water retention can lower serum sodium. Infection, volume loss, tubular injury, and HRS may contribute to AKI, sometimes together. Ascites plus AKI does not by itself diagnose HRS.

## Discuss

Why can a patient have swollen legs and still have poor effective arterial filling?

Interstitial fluid, venous congestion, and effective arterial filling describe different compartments and pressures. Decide which mechanisms are present using the examination, urine, laboratory trends, and response to treatment.

## Sources

- [Mullens et al.: venous congestion and worsening kidney function](https://pubmed.ncbi.nlm.nih.gov/19215833/)
- [ADQI–ICA 2024 consensus: AKI in cirrhosis](https://pubmed.ncbi.nlm.nih.gov/38527522/)
- [KDIGO glomerular-disease guideline executive summary](https://pubmed.ncbi.nlm.nih.gov/34556300/)

## Related cases

- [Case 06: The Breathless Farmer](https://urinenephrology.org/2025_UDPA_Lectures_Live/case-based-lectures/cbl-06-the-breathless-farmer.html#case-visual-summary)
- [Case 29: The Cirrhotic's Creatinine](https://urinenephrology.org/2025_UDPA_Lectures_Live/case-based-lectures/cbl-29-the-cirrhotic-s-creatinine.html#case-visual-summary)