Your kidneys keep you healthy by filtering your blood.
The kidneys have small blood vessels called glomeruli. Glomeruli remove waste, which enters the urine, and reabsorb protein that stays in the blood.
If your kidneys aren’t functioning properly, the protein can leak into your urine. The result is high protein levels in the urine, which is known as proteinuria.
The different types of proteinuria include:
Glomerular proteinuria is the most common type. Albuminuria, or excess amounts of the protein albumin, is a subtype of glomerular proteinuria.
Proteinuria may be related to temporary conditions, such as 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. They may 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, such as proteins, to the kidneys. Without enough fluid, it’ll have difficulty delivering nutrients. In turn, the kidneys can’t properly recapture proteins. The protein ends up in the urine instead.
Other symptoms of proteinuria depend on the severity of dehydration. You may experience:
Dehydration can be caused by:
- excessive sweating
- 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 protein, which then flows into the urine.
Since high blood pressure develops slowly, you may not have symptoms for years. If it becomes severe, it can cause headaches, shortness of breath, or nosebleeds.
Most cases of high blood pressure don’t have an underlying cause. In some people, high blood pressure is a result of:
- kidney disease
- thyroid disorders
- obstructive sleep apnea
- adrenal gland tumors
- some medications, such as birth control or decongestants
Diabetes mellitus is a metabolic disorder that causes high levels of blood sugar. There are multiple types of diabetes, including type 1 and type 2 diabetes.
With diabetes, high blood sugar forces the kidneys to filter the blood too much. This can cause kidney damage, allowing protein to leak into the urine.
Symptoms of diabetes depend on the severity and type. You may experience:
Proteinuria may indicate glomerulonephritis, or inflammation of the glomeruli.
Normally, when the glomeruli filter blood, they reabsorb protein. If the glomeruli are injured, protein can pass through and enter the urine.
Glomerulonephritis can cause a set of symptoms called nephrotic syndrome. In addition to proteinuria, nephrotic syndrome involves:
- hyperlipidemia, or high blood levels of fat and cholesterol
- swollen feet, legs, or ankles
- hypoalbuminemia, or low blood protein levels
Glomerulonephritis may also cause hematuria, or red blood cells in the urine. Hematuria makes urine look pink or cola-colored.
Typically, glomerulonephritis happens when the immune system attacks the kidneys. It’s been associated with:
- bacterial endocarditis
- hepatitis B
- hepatitis C
- diabetic nephropathy
- high blood pressure
Chronic kidney disease (CKD)
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
- trouble sleeping
- dry, itchy skin
- swollen hands and feet
- low appetite
The following conditions can damage the kidneys and lead to CKD:
- heart disease
- high blood pressure
- interstitial nephritis
- polycystic kidney disease
- recurring kidney infection
If CKD progresses, it can result in kidney failure.
The immune system usually produces antibodies, also known as immunoglobulins, that fight foreign organisms. If you have an autoimmune disease, the immune system makes antibodies 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 (SLE). 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.
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. Individuals with preeclampsia should be carefully monitored.
In severe cases, proteinuria is caused by cancer. Several types of cancer are associated with high urine protein levels, including:
- renal cell carcinoma
- lung cancer
- breast cancer
- colorectal cancer
- non-Hodgkin’s lymphoma
- Hodgkin’s lymphoma
- multiple myeloma
It’s thought that the inflammatory effect of cancer alters kidney function.
In some conditions, such as 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
- skin changes
Other causes of proteinuria include:
- dysfunction that affects the renal tubules
- inflammation of the urinary tract, which may be the result of a condition such as a urinary tract infection or tumor
- overproduction of certain proteins
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.
As kidney damage progresses, more protein will pass into your urine. This may cause symptoms such as:
- frothy, foamy urine
- swelling in the hands, feet, face, or abdomen
- frequent urination
- muscle cramps at night
- low appetite
If you have temporary or mild proteinuria, you likely won’t need treatment. 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 management. Maintaining a moderate weight may help you manage conditions that impair kidney function.
- Blood pressure medication. If you have high blood pressure or diabetes, a doctor might prescribe medication to help lower your blood pressure. Explore the connection between high blood pressure and diabetes.
- Diabetes medication. You may need medication or insulin therapy to help you manage high blood sugar.
- Dialysis. In glomerulonephritis and kidney failure, dialysis is used to help manage high blood pressure and fluid imbalances.
In general, people of African, Hispanic, Latin, Native American, and Asian descent experience kidney conditions more frequently.
Some people are more likely to develop proteinuria. Common risk factors include:
- Age. Older adults tend to experience dehydration and kidney concerns more often. Pregnant people 40 and older have a greater risk of preeclampsia.
- High blood pressure. People with high blood pressure have a higher risk of developing 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.
- A higher body weight. High blood pressure, diabetes, and preeclampsia are associated with having overweight or obesity.
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 will be examined under a microscope.
If the doctor thinks you have kidney concerns, they’ll repeat the urine test three times in 3 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 protein test. In this test, the doctor collects multiple urine samples over 1 day and sends them to a lab.
- Glomerular filtrate rate (GMR) blood test. This test checks your kidney function.
- Imaging tests. You may get an ultrasound or a CT scan, which take detailed photos of your kidneys and urinary tract.
- Kidney biopsy. During a biopsy, a doctor removes a sample of your kidney and examines it for signs of kidney damage.
Proteinuria can be temporary, so some people with proteinuria won’t require treatment.
However, proteinuria often means that your kidneys aren’t properly filtering blood. Therefore, the goal of treatment is to manage any underlying conditions you may have.
If necessary, a doctor can create a treatment plan to help protect your kidneys and ease any related symptoms.