What Causes Protein in Urine?
Aug 14, 2020 • 📖 5 min(s)
Aug 14, 2020 • 📖 5 min(s)
Your kidneys keep you healthy by filtering blood. They have small blood vessels called glomeruli. These structures remove waste, which enters the urine, and reabsorb protein that stays in the blood.
But if your kidneys aren't functioning properly, the protein can leak into your urine. The result is high protein levels in the urine, known as proteinuria.
There are different types of proteinuria, including:
In addition, albuminuria is a type of proteinuria where the excess protein is albumin. It's related to glomerular proteinuria. Glomerular proteinuria is the type being discussed below.
Proteinuria may be related to temporary conditions, like dehydration, or more serious kidney damage. Let's explore the possible causes of proteinuria, along with its symptoms and treatment.
If you have proteinuria, take note of your other symptoms. This will help a doctor identify the underlying cause.
Dehydration happens when your body loses too much fluid. It's a common, temporary cause of proteinuria.
Your body uses water to deliver nutrients, like proteins, to the kidneys. But without enough fluid, it will have difficulty doing so.
In turn, the kidneys can't properly recapture proteins. The protein ends up in the urine instead.
Other symptoms depend on the severity of dehydration. You may experience:
Dehydration can be caused by:
High blood pressure, or hypertension, can weaken the blood vessels in the kidneys. This decreases their ability to reabsorb to protein, which flows into the urine.
Since high blood pressure develops slowly, you may not have symptoms for years. But if it becomes severe, it can cause:
Most cases of high blood pressure don't have an underlying cause. But in some people, high blood pressure is due to:
With diabetes, high blood sugar forces the kidneys to over filter the blood. This can cause kidney damage, allowing protein to leak into the urine.
Symptoms of diabetes depend on the severity and type. You may have:
Proteinuria may indicate glomerulonephritis, or inflammation of the glomeruli.
Normally, when the glomeruli filter blood, they reabsorb protein. But if they're injured, protein can pass through and enter the urine.
Glomerulonephritis can cause a set of symptoms called nephrotic syndrome. In addition to proteinuria, this includes:
It may also cause high blood pressure and hematuria, or red blood cells in the urine. This makes urine look pink or cola-colored.
Typically, glomerulonephritis happens when the immune system attacks the kidneys. It's been associated with:
Chronic kidney disease (CKD) is the progressive loss of kidney function. It may cause proteinuria in the early stages, but it usually doesn't cause any noticeable symptoms.
As CKD progresses, you might experience:
The following diseases can damage the kidneys and lead to CKD:
If CKD progresses, it can result in kidney failure.
The immune system normally produces antibodies and immunoglobulins that fight foreign organisms. But if you have an autoimmune disease, the immune system makes antibodies and immunoglobulins that attack the body's tissues. These substances are called autoantibodies.
If the autoantibodies injure the glomeruli, inflammation can occur. This leads to kidney damage, and eventually, proteinuria.
The following autoimmune diseases are associated with proteinuria:
In preeclampsia, a pregnant person develops high blood pressure at or after 20 weeks of pregnancy. This temporarily impairs the kidneys' ability to filter protein, which causes proteinuria.
Other preeclampsia symptoms include:
Though preeclampsia usually goes away after delivery, it's a serious condition that can lead to preterm birth. Pregnant individuals with preeclampsia should be carefully monitored.
In severe cases, proteinuria is due to cancer. Several types of cancer are associated with high urine protein levels, including:
It's thought that the inflammatory effect of cancer alters kidney function.
In some conditions, like multiple myeloma, kidney damage occurs when abnormal proteins in the blood bind with normal proteins in the urine. As kidney function declines, more protein ends up in the urine.
Though cancer symptoms vary greatly, general symptoms include:
Certain people are more likely to develop proteinuria. Common risk factors include:
In the early stages of kidney damage, you won't have any symptoms. That's because there are only small amounts of protein in your urine.
But as kidney damage progresses, more protein will pass into your urine. This may cause symptoms like:
The only way to diagnose proteinuria is through a urine test, which measures the amount of protein in your urine.
The test takes place in a doctor's office. During the procedure, you urinate into a specimen cup. The doctor places a dipstick, or a small plastic stick coated with chemicals, into the urine sample. If it has too much protein, the stick will change color.
The rest of the urine will be sent to a lab, where it's examined under a microscope.
If your doctor thinks you have kidney issues, they'll repeat the urine test three times in three months. This helps them rule out temporary causes of proteinuria.
A doctor might also use the following tests to determine what's causing your proteinuria:
If you have temporary or mild proteinuria, you likely won't need treatment. But if you have consistent proteinuria, you'll need to treat the underlying condition.
Treatment may include:
Proteinuria often means that your kidneys aren't properly filtering blood. Therefore, the goal of treatment is to manage the underlying condition. A doctor can create a treatment plan to help protect your kidneys.
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