Swelling resulting from buildup of salt and water. The nephrotic syndrome is not itself a disease. The kidneys are two bean-shaped organs found in the lower back. They are about the size of a fist. They clean the blood by filtering out excess water and salt and waste products from food.
Healthy kidneys keep protein in the blood, which helps the blood soak up water from tissues.
But kidneys with damaged filters may let protein leak into the urine. As a result, not enough protein is left in the blood to soak up the water. The water then moves from the blood into body tissues and causes swelling. You may see swelling around your child's eyes, belly, and legs. Your child may urinate less often than usual and may gain weight from the excess water.