Proteinuria Fact Book
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.
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
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.
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.
To test for proteinuria, you will need to give a urine sample. A strip
of chemically treated paper will change color when dipped in urine that
has too much protein. A more sophisticated chemical analysis is needed to
find smaller amounts (microalbuminuria). The most dependable measure of
proteinuria requires you to collect your urine for 24 hours.
will be given a special container and instructions for starting and
stopping the collection and for storing the container.
|Containers for collecting
Your doctor will also want to test a sample of your blood for
creatinine and urea nitrogen. These are waste products that healthy
kidneys remove from the blood. High levels of creatinine and urea nitrogen
in your blood indicate that kidney function is impaired.
If you have diabetes, hypertension, or both, the first goal of
treatment will be to control your blood sugar and blood pressure. If you
have diabetes, you should test your blood sugar often, follow a healthy
eating plan, take your medicines, and get plenty of exercise. If you have
diabetes and high blood pressure, your doctor may prescribe a medicine
from a class of drugs called ACE (angiotensin-converting enzyme)
inhibitors. These drugs have been found to protect kidney function even
more than other drugs that provide the same level of blood pressure
People who have high blood pressure and proteinuria but not diabetes
may also benefit from taking an ACE inhibitor. The National Heart, Lung,
and Blood Institute recommends keeping blood pressure below 125/75 mm Hg
for people with proteinuria greater than 1 gram per 24 hours.
In addition to blood sugar and blood pressure control, the National
Kidney Foundation recommends restricting dietary salt and protein. Your
doctor may refer you to a dietitian to help you follow a healthy eating
- 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
Keeping on Top of Your Condition
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For More Information
American Kidney Fund
6110 Executive Boulevard
Rockville, MD 20852
Phone: (800) 638-8299 or (301)
National Kidney Foundation
30 East 33rd Street
York, NY 10016
Phone: (800) 622-9010 or (212) 889-2210