Edema is due to-
Pathogenesis of edema
Following conditions can cause edema :-
1) The increased hydrostatic pressure of capillaries, e.g. in CHF or DVT.
2) Decreased plasma osmotic pressure of capillaries: It results from Hypoproteinemia. When total plasma protein is below 5 gm/dl (normal 6-8 gm/dl) or albumin is below 2-5 gm/dl (normal 3.5-5 gm/dl) edema takes place. Conditions causing hypoproteinemia are nephritic syndrome, liver cirrhosis, protein-losing enteropathy, and PEM.
3) Defective removal of interstitial fluid by lymphatics: It is due to lymphatic obstruction, which may be inflammatory, neoplastic, post-surgical and post-irradiation.
4) Increased vascular permeability: It occurs in acute and chronic inflammation, and during angiogenesis (new vessels are leaky).
5) Sodium (salt) and water retention: The conditions responsible for this type of edema are ARF, acute glomerulonephritis, renal hypoperfusion, and increase renin angiotensin aldosterone system
(RAAS) activity.
Increased capillary osmotic pressure
Decreased lymph flow
Decreased hydrostatic pressure in capillaries
Both of the above