Nephrotic syndrome occurs when the kidneys are not working properly. Healthy kidneys filter out excess water, salts, and other items from the blood in our body. Large amounts of protein and minerals are lost through urine when kidneys have damaged filters. The body is left without enough protein to soak up water. As a result, the water moves from the blood supply into body tissues. This causes swelling in the tissues where the water pools.

The most common areas of swelling are in the face around the eyes and in the ankles and feet. Fluid can also collect in the lungs, making it difficult to breathe.

Complications of nephrotic syndrome can include:

• Infection, such as peritonitis, cellulitis, and sepsis.
• Blood clots in veins (deep vein thrombosis) or in the lungs (pulmonary embolus).
• Blood clots in the arteries (acute arterial thrombosis). A blood clot in an artery (arterial embolus) can block blood flow to your arm or leg.
• Increased cholesterol or triglyceride levels in the blood (hyperlipidemia).
• Poor kidney function (chronic renal insufficiency) leading to chronic kidney disease. For more information, see the topic Chronic Kidney Disease.
• Growth delays in children, which can result in shorter height as an adult.

Acute nephrotic syndrome can develop quickly over a few days to a few weeks, causing edema (swelling) and possibly kidney failure.³

If another severe medical condition (such as diabetes or high blood pressure) is causing nephrotic syndrome, you may develop complications from the other condition as well.

Most children who have nephrotic syndrome do well with treatment and have a normal life expectancy. Children older than age 12 at the time of diagnosis and adults who also have diabetes or high blood pressure do not respond as well to treatment as do children younger than 12.

Complete recovery is possible. Doctors define complete recovery as living without symptoms or treatment for more than 2 years.¹