Table Graphic Jump Location
Favorite Table | Print
Patient Image not available.

Mrs. V is 62-year-old woman with leg edema for the past 2 weeks.

Image not available.What is the differential diagnosis of edema? How would you frame the differential?

Edema is defined as an increase in the interstitial fluid volume and is generally not clinically apparent until the interstitial volume has increased by at least 2.5–3 L. It is useful to review some background pathophysiology before discussing the differential diagnosis:


  1. Distribution of total body water

    1. 67% intracellular; 33% extracellular

    1. Extracellular water: 25% intravascular; 75% interstitial

  2. Regulation of fluid distribution between the intravascular and interstitial spaces

    1. There is constant exchange of water and solutes at the arteriolar end of the capillaries

    1. Fluid is returned from the interstitial space to the intravascular space at the venous end of the capillaries and via the lymphatics.

    1. Movement of fluid from the intravascular space to the interstitium occurs through several mechanisms

      1. Capillary hydrostatic (hydraulic) pressure pushes fluid out of the vessels

      1. Interstitial oncotic pressure pulls fluid into the interstitium

      1. Capillary permeability allows fluid to escape into the interstitium

    1. Movement of fluid from the interstitium to the intravascular space occurs when opposite pressures predominate

      1. Intravascular (plasma) oncotic pressure from plasma proteins pulls fluid into the vascular space

      1. Interstitial hydrostatic pressure pushes fluid out of the interstitium

    1. In skeletal muscle, the capillary hydrostatic pressure and the intravascular oncotic pressure are the most important.

    1. There is normally a small gradient favoring filtration out of the vascular space into the interstitium; the excess fluid is removed via the lymphatic system.

  3. Edema formation occurs when there is

    1. An increase in capillary hydrostatic pressure (for example, increased plasma volume due to renal sodium retention)

    1. An increase in capillary permeability (for example, burns, angioedema)

    1. An increase in interstitial oncotic pressure (for example, myxedema)

    1. A decrease in plasma oncotic pressure (for example, hypoalbuminemia)

    1. Lymphatic obstruction


Although it is possible to construct a pathophysiologic framework (Figure 15–1) for the differential diagnosis of edema, it is more useful clinically to combine anatomic, pathophysiologic, and organ/system frameworks:


  1. Generalized edema due to a systemic cause and manifested by bilateral leg edema, with or without presacral edema, ascites, pleural effusion, pulmonary edema, periorbital edema

    1. Cardiovascular

      1. Systolic or diastolic dysfunction, or both

      1. Constrictive pericarditis

      1. Pulmonary hypertension

    1. Hepatic (cirrhosis)

    1. Renal

      1. Advanced renal failure of any cause

      1. Nephrotic syndrome

    1. Anemia

      Image not available.The most common systemic causes of edema are cardiac, renal, and hepatic diseases as well as anemia.

    1. Nutritional deficiency

    1. Medications

      1. Antidepressants: Monoamine oxidase inhibitors

      1. Antihypertensives

        1. Calcium channel blockers, especially dihydropyridines

        1. Direct vasodilators (hydralazine, minoxidil)

        1. β-Blockers

      1. Hormones

        1. Estrogens/progesterones

        1. Testosterone

        1. Corticosteroids

      1. Nonselective nonsteroidal antiinflammatory drugs (NSAIDs) and cyclooxygenase-2 inhibitors

      1. Rosiglitazone, pioglitazone

    1. Refeeding edema

    1. Myxedema

  2. Limb edema due to a venous or lymphatic cause, manifested by unilateral or bilateral edema

    1. Venous disease

      1. Obstruction

        1. Deep venous thrombosis (DVT) (see Chapter 14, Dyspnea for a full discussion of lower extremity DVT)

        1. Lymphadenopathy

        1. Pelvic mass

      1. Insufficiency

    1. Lymphatic obstruction (lymphedema)

      1. Primary (idiopathic, often bilateral)

        1. Congenital

        1. Lymphedema ...

Want remote access to your institution's subscription?

Sign in to your MyAccess profile while you are actively authenticated on this site via your institution (you will be able to verify this by looking at the top right corner of the screen - if you see your institution's name, you are authenticated). Once logged in to your MyAccess profile, you will be able to access your institution's subscription for 90 days from any location. You must be logged in while authenticated at least once every 90 days to maintain this remote access.


About MyAccess

If your institution subscribes to this resource, and you don't have a MyAccess profile, please contact your library's reference desk for information on how to gain access to this resource from off-campus.

Subscription Options

AccessMedicine Full Site: One-Year Subscription

Connect to the full suite of AccessMedicine content and resources including more than 250 examination and procedural videos, patient safety modules, an extensive drug database, Q&A, Case Files, and more.

$995 USD
Buy Now

Pay Per View: Timed Access to all of AccessMedicine

24 Hour Subscription $34.95

Buy Now

48 Hour Subscription $54.95

Buy Now

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.