Proteinuria Causes, Symptoms, Diagnosis, Treatment, Prevention

Proteinuria Causes, Symptoms, Diagnosis, Treatment, Prevention

What is proteinuria?

Proteinuria describes a condition in which urine contains an abnormal amount of protein. Proteins are the building blocks for all body parts, including muscles, bones, hair, and nails. Proteins in your blood also perform a number of important functions: protecting you from infection, helping your blood coagulate, and keeping the right amount of fluid circulating through your body.

Proteinuria Causes, Symptoms, Diagnosis, Treatment, Prevention

As blood passes through healthy kidneys, they filter the waste products out and leave in the things the body needs, like proteins. Most proteins are too big to pass through the kidneys' filters into the urine, unless the kidneys are damaged. The two proteins that are most likely to appear in urine are albumin and globulin. Albumin is smaller and therefore more likely to escape through the filters of the kidney, called glomeruli. Albumin's function in the body includes retention of fluid in the blood. It acts like a sponge, soaking up fluid from body tissues.

Inflammation in the glomeruli is called glomerulonephritis, or simply nephritis. Many diseases can cause this inflammation, which leads to proteinuria. Additional processes that can damage the glomeruli and cause proteinuria include diabetes, hypertension, and other forms of kidney diseases.

Research shows that the level and type of proteinuria (whether the urinary proteins are only albumin or include other proteins) strongly determine the extent of damage and whether you are at risk for developing progressive kidney failure.

Proteinuria has also been shown to be associated with cardiovascular disease. Damaged blood vessels may lead to heart failure or stroke as well as kidney failure. If your doctor finds that you have proteinuria, you will want to do what you can to protect your health and prevent any of these diseases from developing.

Several health organizations recommend that some people be regularly checked for proteinuria so that kidney disease can be detected and treated before it progresses. A 1996 study sponsored by the National Institutes of Health determined that proteinuria is the best predictor of progressive kidney failure in people with type 2 diabetes. The American Diabetes Association recommends regular urine testing for proteinuria for people with type 1 or type 2 diabetes. The National Kidney Foundation recommends that routine checkups include testing for excess protein in the urine, especially for people in high-risk groups.

What causes proteinuria?

Proteinuria is the result of protein in the blood passing through the kidneys and into the urine. Diabetes and high blood pressure are common causes of proteinuria. Acute illness or dehydration can result in a transient increase in a urine protein measurement.

Renal causes of proteinuria

Proteinuria can be caused by a number of conditions or disorders of the kidney including:
  • Damage to the kidneys from certain drugs or toxins such as heavy metals
  • Glomerulonephritis (inflammation of the filtering structures of the kidneys)
  • Kidney infection (pyelonephritis) or inflammation
  • Other kidney diseases
  • Polycystic kidney disease (inherited disorder resulting in enlarged kidneys with multiple cysts)

Other causes of proteinuria

Proteinuria can also result from other conditions such as:
  • Acute illness with fever, including urinary tract infection
  • Amyloidosis (rare immune-related disorder characterized by protein buildup in organs and tissues that can cause serious complications)
  • Congestive heart failure
  • Dehydration
  • Diabetes
  • Hypertension (high blood pressure)
  • Preeclampsia (high blood pressure and proteinuria in pregnancy)
  • Systemic lupus erythematosus (disorder in which the body attacks its own healthy cells and tissues)

Who Is at Risk?

People with diabetes, hypertension, or certain family backgrounds are at risk for proteinuria. In the United States, diabetes is the leading cause of end-stage renal disease (ESRD), the result of progressive kidney failure. In both type 1 and type 2 diabetes, the first sign of deteriorating kidney function is the presence of small amounts of the protein albumin in the urine, called microalbuminuria. As kidney function declines, the amount of albumin in the urine increases, and microalbuminuria becomes full-fledged proteinuria.

High blood pressure is the second leading cause of ESRD. Proteinuria in people with high blood pressure is an indicator of declining kidney function. If the hypertension is not controlled, the person can progress to full renal failure.

African Americans are more likely than white Americans to have high blood pressure and to develop kidney problems from it, even when their blood pressure is only mildly elevated. In fact, African Americans ages 25 to 44 are 20 times more likely than their white counterparts to develop hypertension-related kidney failure. High blood pressure is the leading cause of kidney failure among African Americans.

Other groups at risk for proteinuria are American Indians, Hispanic Americans, Pacific Islander Americans, older people, and overweight people. People who have a family history of kidney disease should also have their urine tested regularly.

What Are the Signs of Proteinuria and Kidney Failure?

Large amounts of protein in your urine may cause it to look foamy in the toilet. Also, because the protein has left your body, your blood can no longer soak up enough fluid and you may notice swelling in your hands, feet, abdomen, or face. Alternatively, you may have proteinuria without noticing any signs or symptoms. Testing is the only way to find out how much protein you have in your urine.

Symptoms of proteinuria

In most cases, proteinuria has no symptoms and is detected during a routine screening in people with high blood pressure or diabetes. If protein loss is severe, nephrotic syndrome may develop. In that case, because of low serum albumin levels, fluid leaks from the circulatory system and collects elsewhere in the body, causing swelling or edema. Edema can be present in the:
  • Face and around the eyes
  • Arms, hands, legs, ankles and feet
  • Abdomen

Other symptoms of Proteinuria can include:

  • Foamy urine
  • Weight gain caused by fluid retention
  • Diminished appetite
  • Hypertension

How is proteinuria diagnosed?

Urinalysis covers a number of tests performed on urine, both with special dipsticks and under a microscope. Abnormal presence of cells and urinary casts, tiny tube-shaped particles, may reveal underlying kidney disease.

The Urine Albumin to Creatinine Ratio (UACR) is a test that estimates how much albumin is excreted in a 24-hour period without requiring patients to collect urine for a whole day.

Common proteinuria blood tests check serum creatinine, albumin, cholesterol and blood glucose levels to help determine whether the condition is caused by kidney damage.

If kidney disease is suspected, any of three tests may be conducted:

  • Glomerular filtration rate (GFR): Estimates how much blood passes through these tiny filters. Normal results range from 90 – 120 mL/min,whilelevels below 60 mL/min for three or more months are a sign of chronic kidney disease (CKD).
  • Renal ultrasound scan: Produces an image of the kidneys. It can show obstructions, stones and tumors or cysts.
  • Kidney biopsy: Involves removal of a tiny piece of kidney tissue for examination under a microscope.

How is proteinuria treated?

Proteinuria is not a specific disease. So its treatment depends on identifying and managing its underlying cause. If that cause is kidney disease, appropriate medical management is essential.

Treatment for proteinuria begins with seeking medical care from your health care provider. To determine if you have proteinuria, your health care provider will ask you to provide a urine sample for laboratory testing.

Untreated chronic kidney disease can lead to kidney failure.

In mild or temporary proteinuria, no treatment may be necessary.

Drugs are sometimes prescribed, especially in people with diabetes and/or high blood pressure. These may come from two classes of drugs:

  • ACE inhibitors (angiotensin-converting enzyme inhibitors)
  • ARBs (angiotensin receptor blockers)
  • Proper treatment -- especially in patients with chronic disease such as diabetes and high blood pressure -- is essential to prevent the progressive kidney damage that is causing the proteinuria.

Other treatment for Proteinuria

  • Low-protein diet
  • Low-sodium diet
  • Dietician consultation and a healthy meal plan

Proteinuria Prevention

If you feel you are at risk for proteinuria, speak to your doctor about your concerns.

Get regular blood and urine tests if you feel that you are at risk for proteinuria.

Balance your diet follow your doctors recommend.

Eat lots of fiber, up to 55g each day in the form of whole grains, fresh vegetables and even supplements if necessary.

Keep your condition controlled if you happen to have hypertension, diabetes or both. While these conditions put you at risk for proteinuria, you can prevent a problem by using your medication, a healthy diet and exercise to keep your symptoms under control. If you are struggling with your symptoms, speak to your doctor as soon as possible for ways to further manage your condition.

Keeping in tune with your disease or condition not only makes treatment less intimidating but also increases its chance of success, and has been shown to lower a patients risk of complications. As well, as an informed patient, you are better able to discuss your condition and treatment options with your physician.

How often do I need to have a test for proteinuria?

People who are at increased risk of developing kidney disease should have this test annually as a minimum or as part of their routine checkups by the doctor. The exact frequency should depend on the clinical situation (level of risk) of the patient. It is important that people with chronic kidney disease and diabetes should have a test for proteinuria as part of their regular reviews.

If I have proteinuria, will I need specific treatment?

If proteinuria is confirmed, your doctor will do other tests and examinations to find out the cause. This may include referral to a specialist kidney doctor (nephrologist) who will help to develop your kidney care plan. Your treatment may include medicines; lifestyle changes such as losing excess weight, exercising and stopping smoking, and sometimes changes in your diet.

If you have diabetes, high blood pressure or both, the first goal of treatment will be to control your blood glucose and blood pressure.

Points To Remember

  • Proteinuria is a condition in which urine contains an abnormal amount of protein. 
  • Proteinuria may be a sign that your kidneys are damaged and that you are at risk for end-stage renal disease. 
  • Several health organizations recommend that people be regularly checked for proteinuria so that kidney disease can be detected and treated before it progresses. 
  • Groups at risk for proteinuria and kidney failure include African Americans, American Indians, Hispanic Americans, Pacific Islander Americans, people who are older or overweight, and people who have a family history of kidney disease. 
  • You may have proteinuria without noticing any signs or symptoms. Testing is the only way to find out how much protein you have in your urine. 
  • If you have diabetes or hypertension, or both, the first goal of treatment will be to control your blood sugar or blood pressure.