Pediatric Glomerular Filtration Disorders
Glomerular filtration disorders are diseases affecting the glomeruli—millions of tiny vessels in the kidneys that filter blood. If they become damaged, the kidneys don’t work as they should and the make-up of your child’s blood and fluids becomes imbalanced.
Individually, each of these filters is called a glomerulus, and each is attached to a tube called a tubule that collects fluid. Together, the filter and the tube unit are called a nephron. In healthy kidneys, the glomeruli filter blood, and the waste and excess water move into the tubules and become urine. When the glomeruli become damaged, they’re unable to properly filter the waste and extra fluid.
When the glomeruli don’t work properly, blood proteins such as albumin seep into the urine, causing too much protein to settle in the urine, and too little in the blood. Protein in the blood can draw excess fluid from the body into the blood, where it is then filtered by the kidneys. When albumin leaks into the urine, there’s not enough left in the blood to help filter the extra fluids from the body. Those fluids then build up, causing swelling in the face, feet, ankles or hands. Damage to the glomeruli also affects the blood’s ability to filter waste, so waste accumulates in the blood.
- Glomerulonephritis - refers to inflammation of the membrane lining of the kidney that helps separate wastes and fluid from the blood. It may occur suddenly, which is described as acute, or symptoms may develop more gradually, which is described as chronic. It may be treatable and reversible or it may progress and result in complications including chronic kidney failure. Sometimes no cause can be found.
- Glomerulosclerosis - scarring or hardening of the glomeruli. Glomerulosclerosis can also lead to kidney failure. There are several other types of glomerular diseases, many of them rare.
A frequent cause of glomerulonephritis in children is streptococcal infection, for example, an upper respiratory infection or strep throat. In these cases, glomerulonephritis typically occurs at least a week after your child’s infection. This acute, or sudden, type of glomerulonephritis is most common in children between 3 and 7 years old, but it can occur at any age. It affects boys more often than girls.
Other diseases that may cause glomerulonephritis include
- Alport syndrome - an inherited form of glomerular disease
- Henoch-Schonlein purpura - usually affecting children and causing purple lesions on the skin and the organs in the body
- Polyarteritis nodosa - an inflammatory disease affecting the arteries
- Systemic lupus erythematosus (lupus or SLE) - a systemic immune disease
- Wegener vasculitis - a disease that results in inflammation of all the body’s organs
The scarring that causes glomerulosclerosis can come from use of medications or be caused by kidney diseases. Glomerulonephritis can cause the scarring that leads to glomerulosclerosis.
Your child may show no symptoms of some glomerular diseases or may show symptoms related to the type of substances the kidneys are failing to filter out. For example, if your child has a condition called hematuria, your child’s urine may have blood in it and appear as pink or rust colored.
Often, a condition called edema, or swelling from the body’s retention of fluids, is a symptom of glomerular disease. Your child also might have foamy, pink or cola-colored urine. Symptoms of glomerulonephritis may include
- Blood in the urine, which may appear pink or the color of cola
- Decreased output of urine
- Difficulty breathing
- Joint pain or muscle aches
- Rash, especially on the legs and buttocks
- Seizures, caused by high blood pressure
- Sore throat
- Swelling in the hands, ankles, feet, and around the eyes
- Urine that appears foamy
- Weight loss
- Yellow or brown appearance to the skin
Tests and Diagnosis
Many diseases can affect how well your child’s kidneys function, and it’s possible that the glomeruli, the tiny vessels in kidneys that filter the body’s blood, can stop working correctly.
When the glomeruli stop filtering as they should, your child may have no symptoms at first. Eventually, though, the disorder in the glomeruli begins causing problems in the kidneys and around the body.
Your child’s doctor may detect signs of glomerulonephritis and other glomerular diseases as part of your child’s routine checkup. But if you notice symptoms in your child, your child’s doctor will take a complete medical history and perform a thorough examination.
Your doctor will order one or more tests to diagnose a glomerular filtration disorder, such as
- Urine tests - determines whether there is blood or excess protein in the urine, and to gather information about kidney function
- Blood tests - such as glomerular filtration rate, which calculate how kidneys are functioning
- A chest X-ray
- An electrocardiogram - which measures the electrical activity of the heart and can reveal abnormal rhythms or muscle damage in your child’s heart
- A renal (kidney) ultrasound - provides the doctor with information about the size and shape of the kidney and helps detect cysts, stones, obstructions, masses and other problems in the kidney. The test is painless and noninvasive. A technologist moves a probe over the kidney or bladder, creating sound waves that bounce back, forming an image on a video screen.
- A renal (kidney) biopsy - allows the doctor to take a sample of kidney tissue to be analyzed. The sample determines the nature and extent of the specific disease causing glomerular damage. Your child will receive a light sedative and local anesthesia, and the doctor will direct a biopsy needle into the kidneys, guided either by images from an ultrasound or a computed tomography (CT) scan. The kidney tissue will be examined in a laboratory.
An accurate and timely diagnosis of glomerular filtration disease is important.
Glomerular filtration disorders affect the glomeruli, the millions of tiny vessels in the kidneys that filter blood. If they become damaged, the kidneys don’t work as they should.
It’s important to seek treatment for your child’s glomerulonephritis, inflammation of the glomeruli, or other glomerular disorder right away to prevent more damage to the kidneys or other complications from the disease.
Usually, a pediatric kidney disease specialist, or nephrologist, treats these disorders, often with
- Medications - which might include diuretics, blood pressure drugs, steroids, immunosuppressive drugs (drugs that stop your child’s natural immune responses), or phosphate binders that reduce the amount of the mineral phosphorous in the blood
- Dialysis - a treatment that filters waste and excess fluid from the blood when the kidneys become unable to do it themselves. Dialysis may be necessary on a short-term or long-term basis.
- Dietary measures - such as fluid restrictions, and a diet low in salt, protein and potassium.
Usually, these treatments can help control problems with glomerular filtration. Sometimes, though, the disorders lead to kidney failure and even dialysis fails to stop the kidneys’ decline.
What are glomerular filtration disorders?
Glomerular filtration disorders, called glomerulonephritis, are a group of diseases involving the glomeruli—millions of tiny vessels in the kidney that filter blood. When the glomeruli are damaged, they can’t adequately function, and blood proteins such as albumin seep into the urine, causing excess levels of protein in the urine and decreased levels in the blood.
What causes glomerulonephritis?
In some cases, the cause of glomerulonephritis is unknown. In other cases, the disease may be caused by infections such as strep throat, or systemic diseases such as lupus.
Is glomerulonephritis always chronic?
Glomerulonephritis may occur suddenly, which is described as acute, or symptoms may develop more gradually, which is called chronic.
Is glomerulonephritis always serious?
While glomerulonephritis can progress and result in complications and chronic kidney failure, more often it is treatable and reversible. In some cases it even resolves without treatment.
What symptoms should I be alert to?
Among the symptoms you may notice or about which your child may complain include edema (swelling) in the hands, feet, ankles, or around the eyes; foamy urine; blood in the urine; decreased output of urine; paleness; fatigue or lethargy; sore throat; difficulty breathing; headache; joint pain or muscle aches; and seizures (caused by high blood pressure).
What tests might my child’s doctor order?
Among the tests your child’s doctor may order are blood and urine tests, a chest X-ray, an electrocardiogram, an ultrasound of the kidneys, and a kidney biopsy.
How is glomerulonephritis treated?
Treatments are targeted toward any underlying cause and also aim to prevent progression and complications. Among the medications that may be used are diuretics, corticosteroids, immunosuppressive drugs, blood pressure drugs, and phosphate binders. Dietary measures may also be a part of treatment, including fluid restrictions and a diet low in protein, potassium, and salt. If the kidneys are unable to function, dialysis may be necessary.
Can glomerulonephritis be prevented?
In most cases, there’s nothing you can do to prevent your child from developing glomerulonephritis.