In patients with nephrotic syndrome, due to glomerular disease, their original barrier function is impaired and a large amount of protein is filtered out of the blood and into the urine.
This in turn leads to low plasma protein and a decrease in plasma colloid osmotic pressure. Fluid leakage from capillaries into the tissue interstitial space increases, reabsorption decreases and oedema occurs. At the same time, the decrease in effective blood volume stimulates an increase in renin-angiotensin-aldosterone activity (an important hormone in regulating water and sodium metabolism) and an increase in the secretion of antidiuretic hormones, further aggravating oedema. Oedema usually starts in the lower limbs.
Prompt consultation with a nephrologist and rational treatment under medical supervision should be sought.