Proteins play many important roles in the body, from regulating fluid levels to building muscles and bones, repairing tissue damage, and preventing infections. Protein is normally found in the blood. A protein called albumin is the main protein in human blood. 

Healthy kidneys remove excess water and waste products from the body in the form of urine. The presence of a small amount of protein in the urine is normal. However, if there is too much protein in your urine (called proteinuria), it can indicate kidney problems or other health conditions. 

Please continue reading to learn what protein in urine (proteinuria) means.

How much protein in urine is normal? 

Less than 150 mg of protein in your urine per day is normal. More than this amount of protein in urine per day indicates proteinuria. Large amounts of protein in the urine 

(more than 3.5 grams per day) is called nephrotic-range proteinuria. It can indicate nephrotic syndrome, a serious condition that causes excessive amounts of protein to leak into the urine, which may be attributable to a number of different causes. 

What does protein in your urine mean?

The presence of large amounts of protein in your urine indicates reduced kidney function due to kidney problems. According to the National Kidney Foundation and American Kidney Fund, some 37 million Americans are living with kidney disease. Some of the kidney diseases and other medical conditions that can result in a positive test of protein in the urine are briefly described below.

Acute kidney inflammation

Acute glomerulonephritis (inflammation of the glomeruli or filters in the kidneys) can lead to protein in the urine. Glomerulonephritis can occur on its own or as a result of other conditions like diabetes or lupus.

Chronic kidney disease

The presence of protein in urine samples can be an early sign of chronic kidney disease (CKD). CKD is a condition in which the kidneys are damaged, leading to a gradual loss of kidney function. Proteinuria is a strong indicator of the progression of CKD. However, not everyone with CKD has proteinuria. Risk factors for chronic kidney disease include high blood pressure, diabetes, heart disease, and a family history of kidney disease.

Nephrotic syndrome

This is a condition associated with the heavy loss of protein in the urine (more than 3.5 grams per 24 hours). In people with nephrotic range proteinuria, damage to the glomeruli causes spilling of large amounts of protein in the urine.

Kidney cancer

Some types of kidney cancers, like renal cell carcinoma, are associated with high protein levels in the urine.

Overuse of nonsteroidal anti-inflammatory drugs (NSAIDs)

High doses and long-term use of NSAIDs such as ibuprofen and naproxen has been linked to acute kidney injury, which in turn can cause too much protein in the urine. 

Preeclampsia 

This is a serious medical condition that occurs in pregnant women. It is associated with high blood pressure and protein in the urine.

Cardiovascular disease

Congestive heart failure is a significant risk factor for kidney disease. Proteinuria is seen in many patients with heart failure.

Immune system disorders 

Proteinuria can be present in certain immune disorders like lupus and Goodpasture’s syndrome.

Blood cancers 

People with certain types of blood cancers, like multiple myeloma, frequently have proteinuria.

Intravascular hemolysis

Health problems like intravascular hemolysis, which result in the destruction of red blood cells, can lead to proteinuria. Protein in urine (proteinuria) occurs because the damaged red blood cells clog the glomeruli and affect the ability of the kidneys to filter blood and remove waste product.

Poisoning 

Mercury, lead, arsenic, and cadmium poisoning, among others, can lead to kidney damage and proteinuria.

Trauma

Patients who have suffered severe trauma or burns can have protein in urine (proteinuria).

Can protein in urine be temporary?

Yes, temporary or transient proteinuria can result from:

• Dehydration 
• Strenuous or intense exercise
• High stress
• Very cold temperatures
• Fever
• Pregnancy
• Low blood pressure
• Inflammation
• Kidney stones

Orthostatic proteinuria or postural proteinuria is a benign condition that is typically seen in people under the age of 30 years. It results in a large amount of protein in the urine when a person is upright and normal levels of protein in the urine when lying down. 

What are the symptoms of protein in urine?

• Foamy, frothy, or bubbly urine
• Swelling in the hands or feet
• Puffy eyelids
• Increased or decreased urination
• Feeling sick, nausea, vomiting
• Muscle cramps
• Dry skin
• Itching
• Numbness
• Fatigue
• Loss of appetite and weight loss
• Shortness of breath
• Trouble concentrating or focusing
• Sleep problems

How serious is protein in urine? 

Protein in the urine is a serious finding. It can be a sign of kidney disease and should be investigated by your healthcare provider. Your family doctor may refer you to a specialist in digestive and kidney diseases. If left untreated, proteinuria can increase your risk of death from cardiovascular disease.

Can a urine test measure protein in urine? 

Yes, there are urine tests that can measure protein in the urine. Your doctor will tell you how to provide a clean catch urine sample to test for protein. You should tell the lab technician if you are on your period or have bleeding from hemorrhoids. 

Your provider may also ask you to collect your urine over a 24-hour period. This urine test provides a more complete picture of the amount of protein in your urine throughout the day. 

You can buy a home dipstick test without a prescription to check for protein in urine. The results of these tests are accurate as long as you follow the instructions carefully on how to collect the urine sample properly.

If your urine protein is high, it can be a sign of kidney disease or kidney damage from other conditions. Your healthcare professional may order additional tests to find out what’s going on. These other tests may include a creatinine clearance test, microalbumin creatinine ratio, glomerular filtration rate (GFR), urine protein electrophoresis, immunofixation (IFE) blood test (protein electrophoresis), other blood tests, imaging tests, and a kidney biopsy.

How do doctors treat proteinuria?

The treatment plan for proteinuria depends on the cause. If kidney disease is the cause of your proteinuria, treatment may include a combination of medications and lifestyle changes. If you have hypertension or diabetes (the two main causes of kidney disease), your health care professional will help you to control your blood pressure or blood sugar. 

Medications used to treat hypertension, such as angiotensin-converting enzyme inhibitors (ACE inhibitors) and angiotensin receptor blockers (ARBs) can help to reduce proteinuria. 

If you have mild or temporary proteinuria, for example, protein in the urine associated with pregnancy, you may not require treatment. 

With the proper diagnosis and treatment, people with high levels of protein in the urine typically do well. However, without treatment, proteinuria can progress to kidney failure and even death. Studies have found that people who have even mild proteinuria have a shorter life expectancy compared to healthy people.

References:

https://medlineplus.gov/lab-tests/protein-in-urine/

https://my.clevelandclinic.org/health/diseases/16428-proteinuria

https://www.sciencedirect.com/science/article/pii/S246802492201227X