Pediatric glomerular filtration disorders

What are pediatric glomerular filtration disorders?

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.

What are the different types of pediatric glomerular filtration disorders?

• Glomerulonephritis - This 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 - This is 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.

What are the signs and symptoms of pediatric glomerular filtration disorders?

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

• Fatigue

• Headache

• Joint pain or muscle aches

• Paleness

• 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

How are pediatric glomerular filtration disorders diagnosed?

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. An accurate and timely diagnosis of glomerular filtration disease is important.

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 - Test such as glomerular filtration rate, which calculate how kidneys are functioning

• X-ray - Chest

• Electrocardiogram (EKG or ECG) - Measures the electrical activity of the heart and can reveal abnormal rhythms or muscle damage in your child’s heart

• 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.

• 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.

What are the causes of pediatric glomerular filtration disorders?

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.

Risk factors

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.

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.

Other diseases that may cause glomerulonephritis include:

• Alport syndrome - An inherited form of glomerular disease

• Henoch-Schonlein Purpura (HSP) - 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

How are pediatric glomerular filtration disorders treated?

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. 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.

• 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 - May include fluid restrictions, and a diet low in salt, protein and potassium.