Proteinuria refers to elevated protein levels in the urine. It is not a disease but a sign that the kidneys are not correctly filtering blood, possibly due to a kidney condition.
Several proteins may leak into urine, but albumin is the most likely. Doctors refer to high levels of albumin, specifically, as albuminuria.
If a person’s urine contains excess protein, it usually indicates that their kidneys are not filtering blood correctly.
This article explores the causes and symptoms of proteinuria and looks into how doctors detect and treat the issue and its cause.
The kidneys are a pair of organs on either side of the spine below the rib cage.
Inside the kidneys are tiny blood vessels called glomeruli. Their job is to cleanse the blood of toxins and metabolites, which they excrete in the urine.
In healthy kidneys, the glomeruli reabsorb protein and keep it in the blood. The kidneys only filter a trace amount of the protein into the urine.
Protein is one of the body’s main building blocks. Getting the right amount of dietary protein, for example, is vital for growth and repair.
If the kidneys are not working as they should, protein can leak into the urine. Health issues that can cause this include the following.
Dehydration
Dehydration may cause temporary proteinuria. If the body loses and does not replace liquids, it cannot deliver the necessary nutrients to the kidneys. This causes problems with how the kidneys reabsorb protein. As a result, they may excrete it in the urine.
Dehydration can cause:
A person can lose fluid through diarrhea, vomiting, or excessive sweating. If they are not drinking enough water to compensate, they may become dehydrated.
High blood pressure
High blood pressure
Someone may not know that they have high blood pressure until a routine physical exam flags it.
High blood pressure can develop over several years. It may not cause any symptoms until it becomes more severe. In this case, it may cause headaches, nosebleeds, and shortness of breath.
Diabetes
Diabetes is a disease that affects the hormone insulin and results in high levels of blood sugar.
In someone with type 1 diabetes, the pancreas does not produce enough insulin. In a person with type 2 diabetes, the pancreas makes enough insulin, but the body cannot use it efficiently.
High blood sugar can force the kidneys to work too hard as they filter the blood, leading to kidney damage. This damage may allow protein to leak into the urine.
People may experience various symptoms of diabetes, including:
- frequent urination
- increased thirst and hunger
- fatigue
- blurry vision
Glomerulonephritis
Glomerulonephritis refers to inflammation of the glomeruli, which are tiny blood vessels in the kidneys. It can cause protein to enter the urine and can also result in nephrotic syndrome.
Nephrotic syndrome is a set of symptoms that can include:
- swelling of the legs and feet
- high blood pressure
- elevated cholesterol
Changes in the immune system cause some forms of glomerulonephritis. It may also run in families, but the cause is often unclear. A person may have a single isolated incidence of this and then develop a chronic form years later.
Chronic kidney disease
Chronic kidney disease (CKD) is also known as chronic renal disease and refers to a gradual loss of kidney function. This prevents the kidneys from filtering the blood properly and can cause protein to seep into the urine.
There are often no symptoms in the early stages of CKD, but a person may experience:
- fatigue
- difficulty concentrating
- a reduction in appetite
- trouble sleeping
- swollen feet and ankles
- dry, itchy skin with puffiness around the eyes
- an increase in urination, especially at night
CKD progresses gradually and may eventually lead to kidney failure.
The two primary causes of CKD are diabetes and high blood pressure. Other kidney problems, such as glomerulonephritis, recurring kidney infections, and polycystic kidney disease, can also lead to CKD.
Autoimmune diseases
These diseases involve the immune system attacking tissues. This occurs as a reaction to autoantibodies, which are antibodies, a type of protein, and immunoglobulins, a family of chemicals.
Sometimes, these diseases
Autoimmune diseases that may lead to proteinuria include:
- Systemic lupus erythematosus: Also called SLE, this mainly affects the skin and joints but can cause kidney damage.
- Immunoglobulin A (IgA) nephropathy: This causes IgA to build up in the glomeruli, leading to proteinuria.
- Goodpasture’s syndrome: This rare disease can cause life threatening bleeding in the lungs and damage the kidneys, leading to kidney failure.
Preeclampsia
Preeclampsia is a pregnancy complication that usually begins after
Symptoms of preeclampsia include:
- swelling of the hands and face
- a headache and vision problems
- abdominal pain
- weight gain
People with preeclampsia need careful medical supervision, as it can cause preterm birth.
People with diabetes or high blood pressure have a
Additional risk factors include:
- being over the age of 65
- having overweight or obesity
- having preeclampsia
- having a family history of kidney disease
A person with early stage kidney damage may have no symptoms. As the condition progresses, the person may have:
- a swollen face
- swollen hands or feet
- foamy urine
- more frequent urination
- fatigue
- high blood pressure
- high cholesterol
- breathing difficulties
Healthcare professionals test for proteinuria by analyzing a urine sample. This often involves using a plastic tool called a dipstick. It has a coating of chemicals that changes color according to the protein levels in the urine sample.
However, dipstick tests are
Another test involves collecting urine over 24 hours to compare levels of the protein albumin with those of the waste product creatinine.
A healthcare professional may also use a glomeruli filtration rate, or GFR, blood test to determine how well the kidneys filter blood.
The best approach depends on the issue causing proteinuria, its severity, and whether it is temporary or chronic.
A nephrologist, who is a doctor who specializes in kidney health, may recommend:
- Lifestyle changes: These may include maintaining a moderate weight, exercising more, and stopping or avoiding smoking.
- Medications: If a person has high blood pressure or diabetes, the doctor may prescribe medications that help control these conditions.
- A special diet: The American Kidney Fund says that a kidney-friendly diet low in minerals and protein may help manage kidney problems.
Proteinuria refers to high protein levels in the urine. It shows that the kidneys are not filtering blood as they should.
Causes of proteinuria can be temporary, such as dehydration, or chronic, such as an autoimmune disease. People with diabetes or high blood pressure have the highest risk of proteinuria.
Healthcare professionals treat proteinuria by addressing the underlying cause. They may also suggest a special diet to help improve kidney function.