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:

  • glomerular proteinuria
  • tubular proteinuria
  • overflow proteinuria
  • post renal proteinuria

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

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:

  • fatigue
  • headaches
  • dizziness
  • increased thirst
  • dark-colored urine
  • decreased urination
  • dry mouth or skin

Dehydration can be caused by:

  • diarrhea
  • vomiting
  • excessive sweating
  • fever
  • not drinking enough water

High blood pressure

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:

  • headaches
  • shortness of breath
  • nosebleeds

Most cases of high blood pressure don’t have an underlying cause. But in some people, high blood pressure is due to:

Diabetes mellitus

Diabetes mellitus is a metabolic disorder that causes high levels of blood sugar. There are several types of diabetes, including type 1 and type 2 diabetes.

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:

  • increased thirst and hunger
  • frequent urination
  • fatigue
  • blurry vision
  • unexplained weight loss

Glomerulonephritis

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

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:

  • shortness of breath
  • frequent urination
  • hiccups
  • fatigue
  • nausea
  • vomiting
  • trouble sleeping
  • dry, itchy skin
  • swollen hands and feet
  • poor appetite

The following diseases can damage the kidneys and lead to CKD:

  • glomerulonephritis
  • diabetes
  • high blood pressure
  • heart disease
  • interstitial nephritis
  • polycystic kidney disease
  • recurring kidney infection

If CKD progresses, it can result in kidney failure.

Autoimmune diseases

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:

  • Systemic lupus erythematosus. While systemic lupus erythematosus (SLE) mainly involves the skin and joints, it can also affect the kidneys.
  • Goodpasture syndrome. In Goodpasture syndrome, the autoantibodies specifically attack the kidneys and lungs.
  • IgA nephropathy. IgA nephropathy happens when deposits of immunoglobulin A accumulate in the glomeruli.

Preeclampsia

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:

  • swollen hands and face
  • headaches
  • blurry vision
  • abdominal pain on the right side
  • increased weight gain

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.

Cancer

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:

  • unexplained weight loss
  • fatigue
  • fever
  • pain
  • skin changes

Certain people are more likely to develop proteinuria. Common risk factors include:

  • Age. Adults 65 and older are more susceptible to dehydration and kidney issues. Pregnant people older than 40 have a greater risk of preeclampsia.
  • High blood pressure. People with high blood pressure have higher risk for diabetes and kidney disorders.
  • Diabetes. Diabetes is the most common cause of CKD. It’s also associated with preeclampsia and glomerulonephritis.
  • Family history. You’re more likely to develop proteinuria if you have a family history of kidney disease or preeclampsia.
  • Certain ethnicities. People of African American, Latino, American Indian, and Asian descent have a greater risk of kidney issues.
  • Being overweight or obese. High blood pressure, diabetes, and preeclampsia are associated with being overweight or obese.

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:

  • frothy, foamy urine
  • swollen hands, feet, face, or abdomen
  • frequent urination
  • muscle cramps at night
  • nausea
  • vomiting
  • poor appetite

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:

  • 24-hour urine collection. In a 24-hour urine test, your urine is collected over 24 hours and sent to a lab.
  • Glomerular filtrate rate (GMR) blood test. This test checks your kidney function.
  • Imaging tests. You may get an ultrasound or CT scan, which take detailed photos of your kidneys and urinary tract.
  • Kidney biopsy. A sample of your kidney is removed and examined for signs of kidney damage.

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:

  • Dietary changes. If you have kidney disease, diabetes, or high blood pressure, a doctor will recommend specific diet changes.
  • Weight loss. Losing weight can manage conditions that impair kidney function.
  • Blood pressure medication. If you have hypertension or diabetes, the doctor might prescribe medication to help lower your blood pressure.
  • Diabetes medication. You may need medication or insulin therapy to control high blood glucose.
  • Dialysis. In glomerulonephritis and kidney failure, dialysis is used to manage high blood pressure and fluids.

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.