Glomerulonephritis (gluh-MARE-you-low-ne-FRY-tis) is an inflammation of the glomeruli, the parts of the filtering units (nephrons) of the kidney that contain a network of capillaries (tiny blood vessels). More to Know Kidneys filter the blood. The main functional units of the kidney, where the filtering takes place, are called nephrons. Each kidney has about a million nephrons, and each nephron has one glomerulus (singular of glomeruli). Glomerulonephritis damages the glomeruli, causing symptoms such as blood in the urine, foamy urine, and swelling (edema) around the face, eyes, ankles, legs, and abdomen. Keep in Mind Some cases of glomerulonephritis get better on their own. Others respond well to treatment, and most of the time, any damage done to the kidneys heals completely. Only in rare cases does glomerulonephritis cause long-term kidney problems. All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts. Back to Articles Related Articles A to Z: Nephrotic Syndrome Learn about conditions that affect the kidneys and urinary tract. Read More A to Z: Hematuria (Blood in Urine) Learn more about hematuria (blood in urine) and how it's treated. Read More Glomerulonephritis With glomerulonephritis, tiny filtering units in the kidneys stop working properly, causing problems like too much fluid in the body and swelling. Most of the time it can be treated. Find out more. Read More Blood in the Urine (Hematuria) Hematuria is pretty common, and most of the time it's not serious. Find out what causes blood in the urine and what to do about it. Read More Kidney Disease Sometimes, the kidneys can't do their job properly. In teens, kidney disease is usually due to infections, structural issues, glomerulonephritis, or nephrotic syndrome. Read More Kidney Diseases in Childhood The kidneys play a critical role in health. When something goes wrong, it could indicate a kidney disease. What are kidney diseases, and how can they be treated? Read More Kidneys and Urinary Tract The kidneys perform several functions that are essential to health, the most important of which are to filter blood and produce urine. Read More When Your Child Has a Chronic Kidney Disease Parents of kids who have a chronic kidney disease often worry about what might happen next, how their child feels, and what treatments are likely to be involved. Find answers here. Read More Your Kidneys You need at least one kidney to live. Find out why in this article for kids. Read More Kidney Stones Kidney stones mostly happen to adults, but sometimes teens can get them. Find out what kidney stones are, how to treat them, and ways to help prevent them. Read More Kidneys and Urinary Tract The bean-shaped kidneys, each about the size of a child's fist, are essential to our health. Their most important role is to filter blood and produce urine. Read More Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor. © 1995-2021 KidsHealth®. All rights reserved. Images provided by The Nemours Foundation, iStock, Getty Images, Veer, Shutterstock, and Clipart.com.