Nephrotic syndrome (NS) is a condition that is often caused by any of a group of diseases that damage the kidneys' filtering system, the glomeruli. The structure of the glomeruli prevents most protein from getting filtered through into the urine. Normally, a person loses less than 150 mg of protein in the urine in a 24-hour period. Nephrotic-range proteinuria, the urination of more than 3.5 grams of protein during a 24-hour period, or 25 times the normal amount, is the primary indicator of NS. About two in every 10,000 people experience nephrotic syndrome. Nephrotic syndrome prevalence is difficult to establish in adults because the condition is usually a result of an underlying disease.
In children, it is diagnosed in more boys than girls, usually between 2 and 3 years of age. In addition to proteinuria, there are three main symptoms of nephrotic syndrome associated with protein leaking into the urine: 1. Hypoalbuminemia (low level of albumin in the blood) 2. Edema (swelling). Hypoalbuminemia is a low level of albumin (a protein) in the blood due to proteinuria. Low albumin in the blood causes fluid to move from the blood into the tissue, causing swelling. The kidney perceives the decrease of fluid in the blood and aggressively retains as much fluid and salt as it can. This contributes to the body's fluid-overload state.