Glomeruli are tiny blood vessels in the kidneys that normally filter salt, water and waste products from the blood. They keep protein in the blood, which helps them absorb water from tissues. When these filters are damaged, protein can leak from the blood into the urine, resulting in proteinuria—an excess of protein in the urine. Proteinuria is also called albuminuria or urine albumin.
If your child has proteinuria, it’s often not serious. But sometimes, it can indicate a more serious problem with the kidneys. You should watch for any signs that your child’s fluids seem out of balance and check with a doctor.
If proteinuria indicates a kidney disease, your doctor will refer your child to a nephrologist, a doctor who specializes in treating kidney diseases.
Your child may have no symptoms while in the earliest stages of proteinuria. As large amounts of protein move from the blood to the urine and out of the body, the following signs and symptoms may occur and may indicate progression of kidney disease.
If you or your child’s pediatrician suspect that your child has proteinuria, a condition in which protein leaks from the blood into the urine, the doctor will recommend a urine test.
In the past, a 24-hour urine collection was required to diagnose proteinuria. The patient would collect urine in a single container from the first visit to the bathroom in the morning through the first visit on the next day. This test may still be used, but most of the time, a simple urine test can be done in a doctor’s office to test how much protein is in your child’s urine. A chemically-treated paper dipped into the urine sample will change color if protein levels are high.
If your child has no symptoms and a urine sample collected first thing in the morning indicates no protein or only trace amounts, the doctor may suggest that your child be tested again in a year. If protein is discovered in the urine, another first morning sample should be tested and also examined under a microscope, and further urinalysis— the physical, chemical, and microscopic testing of a sample of urine—will be necessary. If the urine tests reveal excess protein and urinalysis results are abnormal, your child may need further evaluation because if the proteinuria persists, it can mean that your child’s kidney function is declining.
To check your child’s overall and kidney health, the doctor will ask about your child’s complete medical history, perform a physical examination and take blood samples to measure levels of creatinine and urea nitrogen—waste materials that are filtered by the kidneys in healthy people. Excess amounts may indicate poor kidney function.
In some cases, the doctor may recommend an ultrasound of the kidneys to detect structural damage or abnormalities. This test provides the doctor with information about the size and shape of the kidney and helps detect cysts, kidney stones, obstructions, masses in the kidney and other problems. The test is painless and noninvasive. A technologist moves a probe over the kidney from outside the body, which creates sound waves that bounce back from the kidney, forming an image on a video screen.
In rare case, your child may need a kidney biopsy. The doctor may want to look at a piece of kidney tissue under a microscope to try to pinpoint the precise kidney disease. For a biopsy, which involves an overnight hospital stay, your child will receive a light sedative and local anesthesia. The doctor will direct a biopsy needle into the kidney guided either by images from an ultrasound or a computed tomography (CT) scan, a test that uses multiple X-ray images to provide a detailed picture of the body structures. The kidney tissue will be examined to diagnose the kidney disease that is causing protein in the urine.
One of the functions of protein in the blood is to help balance the body’s fluid levels. When protein spills into the urine, it causes fluid to leak into the body’s tissues, which results in swelling.
Although proteinuria is often harmless and may result from stress, fever or exercise, it also can be a sign of a serious underlying kidney disease (also called renal disease) or a disease that started in another part of your child’s body. Proteinuria also may be a sign of another condition, nephrotic syndrome, which may indicate an underlying kidney disease.
The most common risk factors for proteinuria are diabetes and hypertension, or high blood pressure. Both of these diseases can cause kidney damage and proteinuria.
Risk factors include:
Untreated, proteinuria can result in serious kidney problems. It is the most common cause of chronic kidney disease.
If your child has proteinuria, the leaking of protein from blood into the urine, it can signal a more serious problem with the kidneys. In other cases, the problem has no known cause and can be treated easily. Regardless, you should seek treatment for your child right away.
Your child’s pediatrician or a nephrologist, a kidney disease specialist, will treat proteinuria with no known cause, called idiopathic proteinuria, by stopping the flow of protein into the urine. The doctor also will recommend treatment to ease your child’s symptoms, such as swelling and fatigue. Usually, the doctor prescribes medications such as prednisone, which is a corticosteroid. If prednisone fails or causes unwanted side effects, the doctor can recommend other drugs, such as cyclophosphamide, chlorambucil or cyclosporine. In patients with kidney disease who do not respond to these drugs, another type of medication called an ACE inhibitor may be used.
When your child’s doctor determines the cause for proteinuria, your child will receive treatment to correct the problem that is causing protein to leak into the urine and guard against kidney damage. For example, children who have diabetes will need to keep their blood sugar under control. Your child’s doctor may suggest making some changes to your child’s diet to restrict how much salt and protein your child eats.
If proteinuria causes damage to your child’s kidneys, a kidney disease specialist will evaluate the damage and manage the problem, trying to preserve as much of your child’s normal kidney function as possible. Proteinuria is a leading cause of chronic kidney disease, so it is important to keep the condition under control.
American Board of Pediatrics/Nephrology
Proteinuria is excess protein in the urine.
Proteinuria occurs when protein leaks from the blood into the urine and into the body’s tissues. It happens when there’s been damage to the glomeruli, structures in the kidney that filter blood.
People with diabetes and hypertension have a higher risk for proteinuria. Other risk factors include obesity, kidney disease, and a family history of kidney disease.
Some groups of people are more likely than Caucasians to be at risk for proteinuria, including African-Americans, Hispanics, Native Americans, and Pacific Islanders.
While proteinuria can be a sign of kidney disease, it may also be harmless and occur in response to stress, fever, or exercise.
Among the symptoms you might notice in your child is edema (swelling), especially around the eyes, or in the hands, feet, or belly. Your child may also complain of fatigue, have difficulty breathing, or have urine that is foamy or bubbly.
If proteinuria is untreated, it can lead to serious kidney problems.
Your child’s doctor can diagnose proteinuria through a simple urine test. Further tests may be necessary to determine the cause of proteinuria.
The symptoms of proteinuria are generally treated with a steroid medication, such as prednisone. If an underlying cause for proteinuria is determined, further treatment will be targeted to the cause.