Protein in the Urine (Proteinuria)

Understanding What Protein in Your Urine May Mean

Your kidneys act as filters, removing waste products and excess fluid from your blood while keeping important substances, such as proteins, in the bloodstream.

Healthy kidneys allow very little protein to pass into the urine. When the kidney filters are damaged or under stress, protein can leak into the urine. This is called proteinuria. When the protein is specifically albumin, it is often called albuminuria.

Finding protein in the urine does not always mean that you have chronic kidney disease. In some cases, proteinuria is temporary. Your healthcare provider may repeat the urine test and consider other laboratory results before determining the cause.

What Causes Protein in the Urine?

Proteinuria can occur for many different reasons.

Temporary Causes

Protein in the urine may be temporary and can occur with:

  • Fever

  • Dehydration

  • Strenuous exercise

  • Stress

  • Certain infections

In these situations, the urine test may return to normal after the underlying problem resolves.

Kidney-Related Causes

Persistent proteinuria may be caused by kidney conditions such as:

  • Diabetic kidney disease

  • Kidney damage related to high blood pressure

  • Glomerulonephritis

  • IgA nephropathy

  • Lupus-related kidney disease

  • Polycystic kidney disease

  • Other diseases affecting the kidney's filtering units

Other Causes

Protein in the urine may also occur with:

  • Certain medications

  • Some infections

  • Autoimmune diseases

  • Pregnancy-related conditions

  • Less common kidney disorders

Your nephrologist will consider your medical history, medications, blood tests, urine tests, and, when appropriate, imaging or additional testing to determine the cause.

Does Protein in the Urine Mean Kidney Disease?

Not always.

A single urine test showing protein does not automatically mean that you have chronic kidney disease.

Your healthcare provider may:

  • Repeat the urine test

  • Check the urine albumin-to-creatinine ratio (uACR)

  • Review your eGFR and creatinine

  • Look for blood in the urine

  • Review your medications and medical history

Persistent proteinuria, especially when present for three months or longer or accompanied by other abnormalities, may indicate kidney disease and should be evaluated further.

When Should You See a Nephrologist?

A nephrology evaluation may be appropriate if you have:

  • Persistent protein or albumin in the urine

  • Large amounts of protein in the urine

  • Proteinuria together with a reduced eGFR

  • Protein and blood in the urine

  • Swelling or fluid retention associated with protein loss

  • An unexplained increase in creatinine

  • A suspected glomerular kidney disease

  • A family history of kidney disease with abnormal urine findings

Early evaluation can help identify the cause of proteinuria and guide treatment to protect kidney health.

Protein in the Urine Is an Important Kidney Health Marker

Protein in the urine is not a diagnosis by itself. It is a finding that helps your healthcare provider understand whether the kidneys may be damaged or under stress.

Kidney health is best evaluated by looking at the whole picture:

Urine protein + eGFR + creatinine + blood pressure + medical history + changes over time

If protein is found in your urine, your nephrologist can help determine whether it is temporary or whether further evaluation is needed to identify an underlying kidney condition.

Schedule Appointment

What Is Proteinuria?

Proteinuria means that an abnormal amount of protein is present in the urine.

Proteins perform many important functions in the body, including:

  • Helping build and repair tissues

  • Supporting the immune system

  • Carrying hormones and other substances through the bloodstream

  • Helping maintain the balance of fluid inside blood vessels

Because these proteins are important, healthy kidneys normally prevent most of them from entering the urine.

What Is Albuminuria?

Albumin is the most common protein measured in the urine.

A urine test called the urine albumin-to-creatinine ratio (uACR) measures the amount of albumin in the urine relative to creatinine. This test is one of the most important ways to detect kidney damage, sometimes even before the eGFR becomes abnormal.

Can Proteinuria Occur With a Normal eGFR?

Yes.

Protein in the urine can be an early sign of kidney damage even when the eGFR is still normal.

This is why doctors often evaluate kidney health using both:

  • eGFR, which estimates how well the kidneys are filtering blood, and

  • uACR, which looks for albumin leaking into the urine.

Together, these tests provide a much more complete picture of kidney health than either test alone.

Learn more about Kidney Function & eGFR 

Are There Symptoms of Proteinuria?

Small amounts of protein in the urine usually do not cause symptoms.

When larger amounts of protein are lost, some people may notice:

  • Foamy or bubbly urine

  • Swelling of the ankles, legs, hands, or around the eyes

  • Weight gain from fluid retention

  • Fatigue

Many people with proteinuria feel completely well, which is why urine testing is important for detecting kidney problems early.

How Is Proteinuria Evaluated?

If protein is found in your urine, your healthcare provider may order additional tests, including:

  • Repeat urinalysis

  • Urine albumin-to-creatinine ratio (uACR)

  • Urine protein-to-creatinine ratio (UPCR)

  • Blood creatinine and eGFR

  • Blood pressure measurement

  • Blood tests for certain medical conditions

  • Kidney ultrasound or other imaging when appropriate

In some cases, a kidney biopsy may be recommended if the cause of significant proteinuria remains unclear or if a specific kidney disease is suspected.

Can Protein in the Urine Be Treated?

Treatment depends on the cause.

If proteinuria is due to a temporary condition, it may resolve once the underlying issue improves.

If it is related to kidney disease, treatment may include:

  • Controlling blood pressure

  • Managing diabetes, when present

  • Reducing excess salt intake

  • Taking medications that help reduce protein loss from the kidneys

  • Treating the underlying kidney disease

  • Regular monitoring of kidney function and urine protein

Reducing persistent proteinuria is often an important treatment goal because it may help protect kidney function over time.

Frequently Asked Questions About Proteinuria

Is protein in the urine always serious?

No. Protein in the urine can be temporary, especially with dehydration, fever, or strenuous exercise. Persistent proteinuria should be evaluated because it may indicate kidney disease.

What is the difference between proteinuria and albuminuria?

Proteinuria refers to protein in the urine in general. Albuminuria specifically refers to albumin, the most common protein measured in urine and an important marker of kidney damage.

Can dehydration cause protein in the urine?

Yes. Dehydration and some acute illnesses can cause temporary proteinuria. Your healthcare provider may repeat the test after the underlying issue has improved.

Can proteinuria occur with a normal eGFR?

Yes. Protein in the urine can appear before the eGFR decreases, which is why both urine albumin testing and eGFR are used to assess kidney health.

Can protein in the urine go away?

It depends on the cause. Temporary proteinuria may resolve completely. When proteinuria is caused by chronic kidney disease, treatment focuses on reducing protein loss and protecting kidney function.

Learn More

This information is intended for general educational purposes and does not replace medical advice. Urine protein results should be interpreted by your healthcare professional in the context of your individual health and laboratory findings.