Children's Hospital Colorado

Proteinuria and Nephrotic Syndrome

What is proteinuria?

Kidneys are constantly filtering blood. Thousands of tiny filters (glomeruli) in each kidney know what should stay in the blood and what should pass through as urine. If too much protein gets into your child's urine, it is called proteinuria.

What is nephrotic syndrome?

When too much protein leaves the blood and goes into urine, the level of protein in the blood gets too low. When this happens, some of the fluid that makes up the blood leaks into the tissues, causing parts of the body to swell. This is called the nephrotic syndrome.

What causes proteinuria and nephrotic syndrome?

In most cases, the cause of protein leaking into urine is unknown. Sometimes a child can be born with a very rare kidney disease that causes high amounts of protein in the urine; this is likely diagnosed shortly after birth. But the more common findings of proteinuria can occur at any time and age, and the majority of cases are mild and unnoticed by the person who has it.

Anybody can get nephrotic syndrome, and like all forms of proteinuria, there is no known cause. 85% of children with nephrotic syndrome  have something called minimal change disease, which means that if one were to take a sample of the kidney (called a kidney or renal biopsy), the filters look nearly normal and protein loss responds well to treatment. Since 85% is a large portion of cases, minimal change disease is suspected most of the time. 

Cases with abnormal filter patterns are known as focal segmental glomerulosclerosis, mesangial nephropathy and membranous nephropathy. They are more serious and in some cases a decrease in kidney function may occur. If these conditions are suspected, a kidney biopsy may be needed. Nephrotic syndrome can occur in other conditions as well, for example severe glomerulonephritis, and response to treatment will vary.

What are the signs and symptoms of proteinuria and nephrotic syndrome?

Proteinuria itself does not cause injury to the body or kidneys, but since it may be a sign of possible kidney disease, it deserves attention. Nephrotic syndrome is caused by various disorders that affect the kidneys, which leads to the release of too much protein in the urine.

What tests are used to diagnose nephrotic syndrome?

Your doctor can diagnose the problem by examination and by ordering blood and urine tests. The blood test can show how low the protein level is, and even more importantly show that the kidney function is otherwise normal, which it often is.

Protein can be found in the urine by putting a special dipstick into a urine sample. Your child's pediatrician can administer this quick test of the urine in their office. If the test is positive for protein, it's still possible that it may be a "false positive," so the doctor will send your child's urine to a laboratory for a more specific measurement.

If the second test reveals that there really is proteinuria present, the doctor will order some routine blood work to ensure the kidneys are otherwise working well. The doctor may include another testing of the urine and possibly an ultrasound of the kidneys, just to make sure there are no other related problems. All this can be done routinely as an outpatient, unless your child is sick (very commonly, the child will not be sick at all).

In mild cases, where the amount of protein is higher than normal but not considered very high, one of the next steps is to measure the amount of protein in urine that is collected in the bladder when lying down. That specimen will likely be collected first thing after getting out of bed and taken to the laboratory for protein measurement. If this sample has a normal amount of protein, it means "extra" protein only leaks into the urine during upright posture. This type of protein leak is not considered a problem and requires no further attention. If the proteinuria is not related to posture it may still not be a problem, but your child's doctor will continue measuring it every 4-6 months to see if clears up on its own. If there is a steady increase in proteinuria, your doctor will refer you to a pediatric nephrologist.

How is proteinuria and nephrotic syndrome treated?

In cases of significant urine protein loss, a drug called prednisone is used to normalize blood protein and reduce swelling. There is a strict treatment schedule that takes several months and the dosage is gradually lowered over time until the treatment course is complete. The prednisone should be taken exactly as prescribed to have the best chance of a lasting response.

Response to the prednisone does not happen immediately, so there are times when your child may need to have the protein (albumin) put back into the blood through a vein. It may be necessary to administer albumin intravenously more than once, but this can be done as an outpatient procedure in an emergency department of the hospital. If your child appears very ill, he or she may be admitted to the hospital for treatment, but this is less common.

As long as the kidneys are otherwise working normally and response to treatment continues to keep the urine free of protein, there are no other treatment concerns. However, since any issue affecting the kidneys can cause high blood pressure (hypertension), your child may also need to take medicine for that condition.

In most cases, one treatment course is all that is needed and the condition doesn't return. Sometimes, the protein leak returns while the prednisone dosage is being decreased or months or years after the treatment stops. When that happens it’s called a "relapse" and treatment must start all over again.

Why choose Children's Hospital Colorado for your child's treatment?

Your child's doctor can refer you to a nephrologist at the Children's Colorado Kidney Center at any time. Our specialists may continue the treatment your doctor prescribed or recommend additional medications and obtain long term testing of the blood and urine. A referral to the Kidney Center doesn't mean that prior treatment isn't working; your child's doctor may simply feel it's necessary for you to get direct care from a nephrologist, especially in complicated cases. The pediatric nephrologists at Children's Colorado have the expertise and experience to recommend alternate treatments when necessary.

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