The kidneys of people with nephrotic syndrome don't work properly, causing large amounts of protein to leak into their urine. It can affect people of any age, but is often first seen in children aged between two and five years. The loss of protein can cause a range of problems, including swelling of body tissues and a greater chance of catching infections. Historically, all children died, usually within the first 6 months of life, but now with aggressive treatment an extended survival can be achieved. Early intravenous albumin supplementation to replace renal losses, nutritional support, vitamin and thyroxine replacement, and rapid management of the complications of infection and thrombosis allow initial stabilisation.
Symptoms can usually be controlled by medication, with steroids often used. Children with nephrotic syndrome have times when their symptoms are under control (remission), followed by times when symptoms return (relapses). Most will relapse less frequently as they get older, eventually "growing out of it" by their late teens. Most children with nephrotic syndrome respond well to steroids and aren't at risk of kidney failure. Most children with nephrotic syndrome have what doctors call "minimal change disease".