Edema and kidney disease related to some?

Causes of renal edema is more complicated.
May be:
① glomerular filtration rate, but the ball - tube imbalance, namely tubular reabsorption function relatively normal;
② renin - angiotensin - aldosterone system activation-induced sodium retention; ③ lot of protein loss caused by reduced plasma colloid osmotic pressure, moisture from the intravascular elected.
In short, sodium retention and water ran into the tissue space is the basis of renal edema caused.
Some chronic kidney damage, although kidney tissue damage is heavy, but the ability of renal tubular reabsorption of water is reduced even more significantly, this time, even if the glomerular filtration rate drop very low, due to the tubular reabsorption capacity than glomerular filtration rate is even worse, no sodium retention, so the patient can no edema or edema is very light.
Kidney damage in some patients with nephrotic syndrome is not too heavy, this time only minor pathological changes in kidney disease, damage to the basement membrane charge barrier based, but due to the large loss of albumin, the patient plasma colloid osmotic pressure drop, water toward the interstitial space. At the same time due to the relocation of water, blood volume decreased activation of the renin-angiotensin system, causing sodium retention. Such patients severe edema can occur pleural effusion, ascites or pericardial effusion, like a big "bag." But by hormones and other drugs, can quickly recover.
Thus, although the renal sodium retention and edema on the basis of all the water toward the tissue space, but because of their different emphases produce edema, edema is not entirely consistent. The varying degrees of renal lesions and this degree does not necessarily relevant. That there is no direct relationship between the degree of edema and kidney damage.