Also Known As
Protein in urine
Albuminuria
This article was last reviewed on
This article waslast modified on November 29, 2017.
What is proteinuria?

Proteinuria is a condition characterized by the presence of greater than normal amounts of protein in the urine. It is usually associated with some kind of disease or abnormality but may occasionally be seen in healthy individuals.

Plasma, the liquid portion of blood, contains many different proteins. One of the many functions of the kidneys is to conserve plasma protein so that it is not eliminated along with waste products when urine is produced. There are two mechanisms that normally prevent protein from passing into urine:

  1. The glomeruli provide a barrier that keeps most larger plasma proteins inside the blood vessels.
  2. The small proteins that do get through are almost entirely reabsorbed by the tubules.

Proteinuria most often occurs when either the glomeruli or tubules in the kidney are damaged. Inflammation and/or scarring of the glomeruli can allow increasing amounts of protein and sometimes red blood cells (RBCs) to leak into the urine. Damage to the tubules can prevent protein from being reabsorbed. Proteinuria may also develop when too much of a small protein is present in the blood and the tubules cannot reabsorb all of it.

Healthy people can have temporary or persistent proteinuria. It may be associated with stress, exercise, fever, aspirin therapy, and exposure to cold. Some people release more protein into the urine when they are standing up than when they are lying down (orthostatic proteinuria), though this condition is rare in individuals over age 30. However, a detectable level of protein in the urine usually indicates the presence of an underlying disease or condition and warrants further investigation to determine the cause.

The most common cause of protein in the urine is kidney damage resulting from:

  • Diabetes – proteinuria is one of the first signs of deteriorating kidney function in people with type 1 and 2 diabetes.
  • Hypertension – proteinuria in someone with high blood pressure is also a first sign of declining kidney function.


Others causes of kidney damage resulting in proteinuria include:

  • Immune disorders (e.g., lupus, IgA nephropathy, Goodpasture's syndrome)
  • Infections
  • Exposure to toxins
  • Trauma
  • Kidney cancer
  • Congestive heart failure


Some other conditions that can cause proteinuria include:

  • Red blood cell destruction and release of hemoglobin that occurs in the bloodstream (intravascular hemolysis)
  • Pre-eclampsia – pregnant women are routinely screened for proteinuria because its presence is associated with pre-eclampsia (also known as toxemia of pregnancy). Pre-eclampsia is a pregnancy-specific disorder where proteinuria and hypertension develop at the same time. Symptoms can include edema (swelling), nausea, and headaches during pregnancy. Rarely, it can cause severe symptoms such as seizures. Pre-eclampsia can be dangerous for both the mother and her baby.
  • Multiple myeloma (cancer of the plasma cells) – proteinuria due to the presence of excess proteins in blood that overflow into the urine (Bence-Jones protein) may be seen in multiple myeloma. Bence-Jones protein consists of an abnormal immunoglobulin light chain (either kappa or lambda) that is produced by monoclonal plasma cells. All immunoglobulins are composed of four protein chains, two light chains and two heavy chains. Bence-Jones protein is made of two immunoglobulin light chains and its presence in urine is often diagnostic of multiple myeloma in the context of other symptoms.
Accordion Title
About Proteinuria
  • Signs and Symptoms

    Laboratory testing is the only way to know for sure if someone has protein in the urine. Several health organizations recommend regular urine tests for people at risk for chronic kidney disease. There are frequently no symptoms associated with proteinuria, especially in mild cases. Large amounts of protein may cause urine to appear foamy. Significant loss of protein from the blood can affect the body's ability to regulate fluids, which can lead to swelling in the hands, feet, abdomen, and face (edema). When symptoms are present, they are usually associated with the condition or disease causing proteinuria.

  • Tests

    The goals of testing for proteinuria include screening individuals who may be at risk, detecting the condition, determining its underlying cause, evaluating the type and quantity of protein being released, and evaluating kidney function. If proteinuria is detected, the person will be monitored at intervals to see if it resolves or becomes worse. Both urine and blood tests will be ordered to evaluate proteinuria.

    Laboratory Tests

    Screening for protein in the urine may be performed as part of a general health exam or as part of a check-up for an individual who is known to have a condition that may cause proteinuria. Some screening tests include:

    • Urine protein – detects the presence of any type of protein that may be in the urine. It can be performed alone on a random urine sample or as part of a urinalysis.
    • Urinalysis – an evaluation of a urine sample for several different substances that may be in the urine, including protein. This test may be used as part of a general health exam.
    • Urine albumin (microalbumin) – a sensitive test that is used to monitor people with diabetes for small amounts of albumin, the main blood protein, in the urine. Over time, diabetes can begin to affect kidney function and this test is an early indicator that diabetes has caused some kidney damage. The American Diabetes Association recommends that people diagnosed with type 2 diabetes be screened annually for low levels of albumin in the urine (microalbuminuria) and that type 1 diabetics be tested 5 years after diagnosis and annually thereafter.


    A positive result on a screening test may be followed by further urine tests to determine how much protein and what type of protein is being lost in the urine:

    • Urine albumin, 24 hour urine – measures the amount of albumin that is escaping into the urine within that timeframe. This test may give the healthcare practitioner a better assessment as to the degree of kidney damage.
    • Urine albumin/creatinine ratio – as an alternative to collecting urine for 24 hours, a random urine sample may be used. In this case, creatinine is also measured. Creatinine is a substance that is released into the urine at a steady rate. When both protein and creatinine are measured in a random sample, a urine albumin/creatinine ratio can be calculated. This calculation corrects for the amount of creatinine in the random sample, more accurately reflecting how much albumin has been lost in the urine.
    • Urine protein, 24-hour urine – measures the amount of protein released in the urine in a 24-hour period; this is a more accurate assessment of the degree of proteinuria than a random urine test.
    • Urine protein/creatinine ratio (UPCR) – measures protein and creatinine in a random sample and corrects it for the amount of creatinine, similar to the urine albumin/creatinine ratio
    • Urine protein electrophoresis – a test used to determine the different types and relative concentrations of protein present in the urine. A urine test specifically for detecting the presence of Bence-Jones protein is sometimes used when multiple myeloma is suspected.
    • When the protein electrophoresis shows an abnormality, an immunofixation test may be performed to quantify the abnormal protein, in addition to an immunoassay evaluation for free light chains.


    In addition to testing urine, there are several other tests that may be used to evaluate kidney function and/or assess the nature of the protein present in the urine. These tests may be done at the same time as urine protein screening or in follow-up. The tests include:

    • BUN (Blood Urea Nitrogen) and Creatinine – blood tests used to evaluate kidney function; urea and creatinine are nitrogen-containing waste products that healthy kidneys move from the blood to the urine. If the kidneys are not functioning properly, urea and creatinine will remain in the blood and the levels will increase. (Note: Although creatinine may be measured in urine samples, a blood sample is also measured to be included as part of the evaluation.)
    • eGFR (estimated Glomerular Filtration Rate) – uses a blood creatinine level along with age and values assigned for sex and race to calculate the estimated rate of urine filtration; the eGFR rate decreases with progressive kidney damage.
    • Creatinine clearance – measures creatinine in a 24-hour urine sample and a blood sample to calculate the amount of creatinine that has been cleared from the blood and passed into the urine; this calculation allows for a general evaluation of kidney function based on the rate of creatinine excretion from the body.
    • Total Protein (TP) – a blood test that measures all of the protein in the serum
    • Albumin – a blood test that measures the concentration of albumin (the most prevalent protein in blood serum)
    • Serum protein electrophoresis – determines the types and relative amounts of protein in blood serum and is compared to the urine electrophoresis pattern to determine if blood is the source of the protein seen in the urine
    • Serum Free Light Chains (SFLC) – a blood test used to help diagnose and monitor conditions associated with an increased production of free light chains such as multiple myeloma


    A healthcare practitioner may also order a kidney biopsy. In a kidney biopsy, a small sample of the kidney tissue is examined with a microscope by a pathologist and may be used to look for evidence of kidney disease or damage. (For more, read the article on Anatomic Pathology.) Additional studies using electron microscopy, immunohistochemistry, and immunofluorescence may also be performed to further evaluate a kidney biopsy.

    Non-Laboratory Tests

    • Imaging scans of the kidney may be performed to detect the presence and determine the severity of kidney disease or damage (For more on these, visit RadiologyInfo.org.)
    • Blood pressure may be measured as part of an investigation of the cause of proteinuria. It is frequently monitored in people who have hypertension or are at risk of developing it.
  • Treatment

    Different underlying conditions can cause proteinuria. The treatment of proteinuria focuses on controlling the underlying condition causing proteinuria and minimizing its progression. Therefore, treatment for each condition is likely to be different. For example, someone with diabetes should carefully monitor and control their blood sugar levels to help to preserve kidney function. Someone with high blood pressure (hypertension) will need to control blood pressure to prevent progressive kidney damage. Pre-eclampsia-related proteinuria during pregnancy will be carefully monitored and usually resolves once the baby is born. Sometimes medications, such as blood pressure medication, will be prescribed depending on the severity of the preeclampsia.

    People with persistent proteinuria and especially those with reduced kidney function may receive recommended dietary changes from their healthcare provider, such as minimizing intake of protein or cholesterol-rich food products. No treatment may be necessary for mild or transient proteinuria.

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