The kidneys are fist-sized organs in the back that are shaped like kidney beans. They filter blood and help remove waste products from the body. Tiny filtering units within the kidneys do this with the help of blood vessels called glomeruli.
If the glomeruli get inflamed (swollen and irritated), it's called glomerulonephritis (gluh-MARE-you-low-ne-FRY-tis). Glomerulonephritis causes the kidneys to stop working properly. This can lead to swelling (from too much fluid in the body) in places like the face, feet, ankles, or legs. Glomerulonephritis also can cause kidney failure and kidney disease, but that's rare.
Glomerulonephritis can be acute (meaning it comes on suddenly) or chronic (developing over several months or years). Often, people don't know they have glomerulonephritis until a routine urine test finds it. How it's treated depends on which type a person has.
Most of the time, glomerulonephritis gets better on its own — and, if it doesn't, there's a lot that doctors can do to prevent further damage.
How the Kidneys Work
One of the main jobs of the kidneys is to filter the waste out of the blood. The body doesn't use everything that we eat and drink, so some of it ends up in our blood as waste, along with other waste products that our bodies make naturally. The kidneys filter blood and remove these waste products and excess fluid, which then leave the body as urine (pee).
The blood filtering happens in tiny structures called nephrons. Each kidney has about a million nephrons. Each nephron has a glomerulus (the singular of glomeruli). The glomerulus, which is a ball of tiny blood vessels, is where the process of removing waste products and fluids from the blood begins. If the glomeruli aren't doing their job properly, it can lead to health problems.
Causes of acute glomerulonephritis include:
- problem with the immune system or diseases that affect it (such as systemic lupus erythematosus or HIV)
- conditions that affect the blood vessels (like vasculitis or Henoch-Schönlein purpura)
- an infection with group A streptococci bacteria (the bacteria that cause strep throat)
While acute glomerulonephritis has known causes, sometimes doctors don't know why people get chronic glomerulonephritis. In rare cases, children can inherit glomerulonephritis from their parents; this is called Alport syndrome.
Early signs of glomerulonephritis include:
- blood in the urine (hematuria, which causes red or brown urine)
- protein in the urine, which can make urine appear foamy in the toilet
- swelling, especially in the morning, around the face, eyes, ankles, legs, and abdomen
- high blood pressure (hypertension)
With acute glomerulonephritis, symptoms come on suddenly, possibly after a skin infection or a case of strep throat. Chronic glomerulonephritis can take several months or years to develop and is found through a urine test.
If the condition isn't caught early and treated, there's a chance of kidney damage or failure. Symptoms of kidney failure include:
- peeing more often
- reduced amounts of urine
- lack of appetite
- nausea and vomiting
- weight loss
- muscle cramps at night
- fatigue (tiredness)
- pale skin
- high blood pressure
- fluid buildup in the tissues
Someone who has these symptoms might not have kidney failure — many other things can cause them. But if your child has any of these problems, it's important to see a doctor right away to find the cause.
At the doctor's office, explain your child's symptoms. The doctor will examine your child and may draw a little blood and get a urine sample for testing. The doctor also might order a kidney ultrasound to get a better look at the kidneys. Ultrasounds use sound waves to create images of organs and other body parts.
In some cases, a biopsy may be done. During this procedure, a tiny sample of kidney tissue is removed and sent to a lab for testing to help find the cause of the glomerulonephritis and check for any kidney damage.
Sometimes, acute glomerulonephritis gets better on its own. When treatment is needed, it's best to start as soon as possible. That way there's less chance of damage to the kidneys.
How doctors treat acute glomerulonephritis in kids depends on what's causing it, what tests (like a kidney biopsy) show, how severe any kidney damage is (based on the biopsy results), what the symptoms are, and a child's age and general health.
Treatment may include:
- fluid restriction (limiting the amount of fluid a child drinks per day)
- a diet low in protein, salt, and potassium
- diuretics (medicines that increase urine production)
- medicines to lower blood pressure (if high blood pressure is a problem)
- antibiotics (if a bacterial infection is causing glomerulonephritis)
- steroids and other drugs that suppress the immune system (if an immune system problem is causing it)
- in severe cases, kidney dialysis (a procedure that cleans the blood and removes fluids from the body)
In most cases of acute glomerulonephritis, the damage to the glomeruli will eventually heal. How long this takes depends on what caused the condition, how long it lasted, and when treatment began.
Lifestyle changes that can help kids with chronic glomerulonephritis include:
- eating a healthy diet while limiting protein, potassium, phosphorus, and salt intake
- getting plenty of exercise (at least 1 hour a day for kids over age 2)
- drinking less fluids
- taking calcium supplements
- taking certain medicines
In rare cases, glomerulonephritis can lead to kidney failure that requires dialysis or a kidney transplant. Fortunately, most kids will never need those procedures and will be able to play sports, participate in favorite activities, and lead perfectly normal lives.