Nephrotic syndrome may occur when the filtering units of the kidney are damaged. This damage allows protein normally kept in the plasma to leak into the urine in large amounts, which reduces the amount of protein in your blood. Since the protein in the blood helps keep fluid in the bloodstream, some of this fluid leaks out of the bloodstream into your tissues, causing swelling, called edema. The swelling may be most noticeable in your legs after you have been standing and around your eyes when you first get up in the morning. Eventually, the swelling in your legs may be there all the time, and it may also occur in other parts of your body.
A child with an established diagnosis of idiopathic childhood nephrotic syndrome who presents at the beginning of either a first or second relapse defined as proteinuria ≥3+ on dipstick, ≥3 g/L on urinalysis or UP/C ≥200 mg/mmol for 3 consecutive days, after remission attained from prior treatment with steroids, during enrolment period prior to start of steroid-sparing agents. Nephrotic syndrome is not a specific kidney disease. It can occur in any kidney disease that damages the filtering units in a certain way that allows them to leak protein into the urine. Some of the diseases that cause nephrotic syndrome, such as nephritis, affect only the kidney.