Kidney Disease

After about 5 to 20 years of diabetes, nearly 30 percent of people with
type 1, and 10 percent of people with type 2 diabetes tend to
develop kidney damage. Kidney damage from diabetes is referred
to as diabetic nephropathy and is popularly known as diabetic kidney
disease. Most people who have diabetic kidney disease also have diabetic
eye disease . As the diabetic kidney disease progresses untreated, it severely
impairs kidney function and may lead to kidney failure. Uncontrolled diabetes
is the major cause of kidney failure, affecting about 380,000 people in
the United States. A strong indicator of diabetic kidney damage is the
leakage of an abnormal amount of albumin in the urine, a condition called
albuminuria or proteinuria.
ALBUMIN IN THE URINE. Albumin is a protein. Proteins are important
constituents of the body. When the blood passes through healthy kidneys,
they filter out waste products but hold nutrients, including protein, to be
used by the body. Normally, large amounts of albumin should not pass in the
urine because albumin is too big to pass through minute filters of the
kidneys. However, when the kidneys are damaged, albumin that the kidneys
should hold for use in the body starts leaking in the urine through damaged
kidney filters.
In healthy people, the amount of albumin present in the urine is less than
30 milligrams per day. In the presence of kidney damage, albumin is
excreted in the urine in larger amounts exceeding 300 milligrams per day,
and depending on the severity of kidney damage, it can be as high as 1,000
milligrams daily. Passing of albumin in the urine is a strong indicator of
kidney damage, and can predict the risk of progression of kidney disease.
In addition to albumin excretion, a raised blood level of creatinine (a waste
substance produced from the normal wear and tear in the body) is another
sign of kidney disease.
KIDNEYFUNCTIONS. Your kidneys work like fine filters that clean harmful
wastes from your blood. Each kidney comprises about 1 million small
filters called nephrons. Each nephron consists of a tiny and minute vessel
called the glomerulus that performs the function of filtration. As the blood
passes through the healthy kidneys, the filters in the kidneys extract harmful
wastes from the blood, excrete them through the urine, and return the nourishing
blood to the system. Another function of the kidneys is to maintain
balance between water and salt, and sodium and potassium in the blood. The
kidneys keep just the right amount of water in your body and excrete excess
water through the urine, thereby regulating your blood pressure.
Diabetes tends to damage all large and minute blood vessels in the body.
The damage to minute blood vessels in the kidneys impairs their filtration
system, and the kidneys develop problems in filtering waste products from
the blood and excreting them through the urine.
SYMPTOMS OF DIABETIC KIDNEY DISEASE. Diabetic kidney disease
may not show any noticeable symptoms in its early stage; when symptoms
appear, the disease may have already become quite severe. For this reason,
every person with diabetes should be regularly screened for kidney disease.
Symptoms of diabetic kidney disease include:
• High blood pressure
• Decreased urine, causing water retention in the bod
• Puffiness around the eyes; swelling on the feet, ankles, hands, face,
and abdomen. Your shoes may not fit your feet, and pants may
become tight on your abdomen due to swelling
• Severe weakness and paleness
• Shortness of breath
• Loss of appetite
• Nausea and vomiting
• Itching
• Hiccups
• Frequent urination at night
• Problem in focusing your mind
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CAUSES OF DIABETIC KIDNEY DISEASE. The causes include:
• Insufficient blood flow to the kidneys (principal cause). Longstanding
diabetes damages the tiny blood vessels of the kidneys,
resulting in reduction of their blood flow. Over time, when the
kidneys do not get enough blood, they become weak and their
filtering apparatus becomes damaged.
• Preexisting high blood pressure.
• Increase in blood pressure at night. Research indicates that high
blood pressure in the night increases the risk for microalbuninuria,
leading to diabetic kidney disease, especially in people with type 1
diabetes.
• Family history of high blood pressure.
• Family history of diabetic kidney disease.
DEVELOPMENT OF DIABETIC KIDNEY DISEASE. The disease progresses
in a typical way:
• In the early stage of diabetic kidney disease, there are generally no
apparent symptoms and the disease occurs silently. The disease is
detected when the urine is tested for albumin. In the early stages of
the disease, albumin starts leaking in the urine in minute but
increasing amounts. Albumin excretion in the urine between 30 to
299 milligrams per day is called microalbuminuria, an indicator that
the tiny vessels of the kidneys have been affected.
Microalbuminuria also raises the risk for heart disease and diabetic
eye disease.
• Blood pressure significantly increases in people with diabetes when
they are passing small amounts of albumin in the urine (microalbuminuria).
• High blood pressure in the presence of microalbuminuria causes
further damage to the kidneys.
• Water retention in the lungs and swelling of various parts of the
body begin to appear in this stage.
• As damage to the kidneys increases, large amounts of albumin are
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passed in the urine. The rate of albumin excretion in this stage will
be greater than 300 milligrams per day, and it can be as high as
1,000 milligrams per day or even greater. This condition is called
macroalbuminuria.
• In the presence of macroalbuminuria, symptoms of diabetic kidney
disease (noted before) become more intense than before, and the
filtration function of the kidneys progressively declines. The
disease, if not treated in this stage, may further become worse.
Extensive kidney damage leads to the final stage of diabetic kidney
disease called the end-stage renal disease (ESRD), a condition that
is virtually kidney failure.
DIAGNOSING KIDNEY DISEASE. People with diabetes should always be
tested for their kidney function. Several tests are available in which urine or
the blood samples are taken to assess the health of the kidneys:
URINE ALBUMIN TESTS. The urine tests that measure albumin excretion in
the urine include:
Dipstick Test. The dipstick test is a basic method of urine testing. In the
albumin dipstick test you dip a testing stick in a urine sample. The stick will
not change color in the absence of albumin in the urine, but its color will
change if significant amount of albumin is present. The dipstick test is
acceptable, but it is not as accurate as a laboratory test. Any positive result
shown by a dipstick test must be confirmed by a test in the laboratory. On a
typical dipstick urine test (Albustix, for example), albumin values are
graded as:
1 + = 30 mg/dL
2 + = 100 mg/dL
3 + = 300 mg/dL
4 + = Over 2,000 mg/dL
LaboratoryUrine-Tests. Laboratories use sensitive methods that measure
even if a tiny amount of albumin is present in the urine. A lab can use any
of the following urine samples for albumin testing:
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Spot Urine Sample. This is a urine sample collected without regard to the
time of day (regardless of fasting or non-fasting state).
First Void Morning Sample. This is the first urine passed in the morning.
The urine is concentrated and contains substances that may not be present
in the urine samples in the rest of the day.
24-Hour Urine Sample. On the first day when you rise in the morning, you
pass your first urine and do not collect it. Thereafter, you pass all the other
urine in a container throughout rest of the day. The next day, when you rise
in the morning, you pass your first urine in the container. The container will
thus contain the 24-hour urine sample, which you will give to the lab
for testing.
Timed-Urine Sample (Less Than 24 Hours). A timed-urine sample
consists of all the urine passed during the last 4 hours or overnight.
Currently, the American Diabetes Association (ADA) strongly suggests
that the spot urine sample, being convenient to administer and reliable,
should be used for detecting diabetic kidney disease.
Albumin-Urine Test Results. Albumin excretion rates, as graded in the two
commonly used urine tests: spot urine sample and the 24-hour urine sample,
are shown below.
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Table 21.1 Albumin Excretion Rates
Condition Spot Urine Sample
(albumin-creatinine
ratio in
micrograms/
milligrams)
24-Hour Urine
Collection (albumin in
milligrams per liter of
urine)
Normal Less than 30 Less than 30
Microalbuminuria 30 to 299 30 to 299
Macroalbuminuria 300 or greater 300 or greater
RELIABILITY OF ALBUMIN-URINE TEST. The presence or absence of
albumin in your urine may not represent the true condition of your kidneys
in certain conditions. A urine test may show a high or low amount of
albumin, unrelated to the actual condition of the kidneys. For example,
albumin in the urine may be high when:
• You have exercised or eaten a high protein food before the test
• You are tested when you have a fever
• You have some urinary tract infection, high blood pressure, or
uncontrolled diabetes at the time of testing
On the contrary, a urine test may not show albumin or show a lower than
actual amount of albumin in the urine when:
• You are dieting
• You have taken an ACE inhibitor (a class of blood pressure
medication) or nonsteroidal anti-inflammatory drugs (NSAID) such
as Motrin and Voltaren
CONFIRMING DIAGNOSIS OF MICROALBUMINURIA. Microabuminuria
should not be diagnosed on the basis of one positive result of the urine test.
For a definitive diagnosis, the test should be repeated in a 3 to 6 month
period, and albumin should be present in a higher than normal amount in at
least two out of three test results. If you have diabetes but your urine test for
albumin is normal, you should have the test repeated at least annually to
monitor the health of your kidneys. When, however, the test shows an
abnormal amount of albumin present in your urine, you should have the
urine albumin test more frequently for monitoring the health of your kidneys.
CREATININE CLEARANCE TEST. As noted before, creatinine is a waste
product produced from the normal wear and tear of the body. The kidneys
excrete creatinine through the urine. However, when the kidneys are damaged
as from diabetic kidney disease, their function is impaired. As a result,
creatinine clearance through the urine diminishes, building up poisonous
wastes in the blood. Two methods are used to test creatinine clearance: a
urine test and a blood test. Both these tests are performed in a laboratory.
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Urine Test for Creatinine Clearance. You collect your 24-hour urine in a
container and give it to the lab for measuring creatinine passed in the urine.
This test measures how much blood volume is cleared of creatinine per
minute by the kidneys. When the kidney function is normal, the normal
ranges of creatinine clearance are:
Men: 97 to 137 milliliters per minute (ml/min)
Women: 88 to 128 milliliters per minute (ml/min)
When the kidney function becomes defective, the amount of creatinine
excreted by the kidneys is less than normal. As a result, creatinine builds up
in the blood, a sign of declining kidney function.
Blood Test for Creatinine. Creatinine in the blood is measured through a
blood test. The normal range of creatinine in the blood is 0.6 to 1.2
milligrams of creatinine per deciliter of blood (mg/dL). (The test results
may vary because laboratories may use different ranges.) Ablood creatinine
level of 2 mg /dL or greater indicates substantial loss of kidney function that
requires immediate treatment.
BLOOD UREANITROGEN (BUN) TEST. Urea, high in nitrogen, is the waste
product left in the blood after the body has used protein. Healthy kidneys
filter out urea from the blood, and send it to the bladder to be excreted in
the urine. When your kidney function is normal, the amount of urea in your
blood is 7 to 20 milligrams per deciliter of blood. Ahigher concentration of
urea in the blood is an indication that the kidneys are not working properly.
OTHER KIDNEY TESTS. When the results of your urine and blood tests
show a decline in the kidney function, the doctor may recommend more
sophisticated tests for making a precise diagnosis of the damage caused to
your kidneys. These tests may include ultrasound scan, CT scan, magnetic
resonance imaging (MRI), angiography, and a kidney tissue biopsy.
KIDNEY FAILURE. The final stage of diabetic kidney disease is called end
stage renal disease (ESRD), a condition that is basically kidney failure. The
kidneys are said to fail when their filtration system is severely damaged and
it stops working. This is a condition in which creatinine clearance through
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the urine falls below 10 to 15 milliliters per minute (ml/min). Creatinine,
under normal conditions, should be cleared from the blood at least at a rate
of 97 ml/min in men and 88 ml/min in women.
In kidney failure, urine discharge is significantly reduced, the body
tends to hold water in excess, and poisonous substances pile up in the blood.
Such a condition is called uremia. Fluid retention in the lungs, swelling on
the body, and weakness in the blood-pumping function of the heart become
quite apparent at this stage. Aperson with ESRD becomes extremely weak.
When the kidneys fail to function, two methods, dialysis and the kidney
transplantation, are the only options left for patients to replace their lost
kidney function in order to remain alive.
HOW TO PREVENT KIDNEY FAILURE. Diabetes, as noted before,
increases the risk for kidney damage, and kidney damage when extensive
can lead to kidney failure. Studies, however, show that if kidney damage
from diabetes is detected and treated in its very early stages, it can be
prevented from progressing to kidney failure. Timely treatment of kidney
damage in its initial stages has been shown to decrease mortality from
kidney disease as much as 94 percent and reduce the need for dialysis and
kidney transplantation up to 73 percent.
The first step in preventing kidney failure is to prevent diabetic kidney
disease in the first place. When, however, you develop diabetic kidney
disease, you should have its proper treatment. But the preventive measures
must still remain in place or the treatment will not work properly. The measures
outlined below are helpful in preventing and treating diabetic kidney
disease, slowing down progression of kidney damage, and preventing
kidney failure.
Blood Sugar Control. Keep your blood sugar as close to normal as safely
possible to prevent kidney damage. Studies show that if you consistently
keep your blood sugar under control for over a period, you can slow down
and even reduce the progression of kidney damage. So, control your blood
sugar and keep your hemoglobin A1C level at less than 7 percent through
all possible means: healthy meals, healthy weight, regular exercise, and
medication if necessary.
Treatment of High Blood Pressure. High blood pressure in many people
with diabetes, especially people with type 1 diabetes, may be due to diabetic
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kidney disease or some other disorder. Whatever the cause, high blood
pressure stresses out the kidneys, and if they are already diseased, high
blood pressure makes them worse. High blood pressure must be treated and
kept as close to a normal range as possible to prevent and treat kidney
damage.
The National High Blood Pressure Education Program and the ADA
recommend that all men and nonpregnant women with diabetes should
keep their blood pressure below 130/80, which is helpful in preventing
diabetes complications, including kidney damage. As a part of treatment,
restricting the amount of salt in your meals will help control your blood
pressure, and reduce swelling on the body associated with diabetic
kidney disease.
Controlling Blood Cholesterol. Raised blood levels of cholesterol have
been shown to impair kidney function. This is probably because when
cholesterol piles up inside the tiny blood vessels serving the kidneys, blood
flow to the kidneys is obstructed and reduced. Lowering of raised blood
cholesterol levels has been shown to stop progression of kidney disease.
According to the current guidelines of the National Cholesterol Education
Program (NCEP), the desirable level of total blood cholesterol in most
people is less than 200 milligrams per deciliter (mg/dL). People who have
a self or family history of heart disease will be better off if they keep their
total blood cholesterol at about 150 mg/dL and the LDL (bad) cholesterol
less than 100 mg/dL. To lower raised blood cholesterol levels, use a low fat
diet, exercise regularly, and add cholesterol-lowering medication
if necessary.
Low-Protein Diet. The main constituents of protein are called amino acids,
substances that are rich in nitrogen. After your body uses protein from the
food you eat, the urea that is rich in nitrogen is left in the blood. The task
of filtering out nitrogen from the blood puts a great strain on the kidneys.
Healthy kidneys successfully manage this strain and filter out urea through
the urine. When, however, the kidneys are damaged, their filtration function
becomes defective and the urea is not properly filtered. As a result, urea
builds up in the blood; raised urea levels tend to cause blood poisoning.
The general medical opinion is that reduced protein intake in healthy
people does not make any difference in preventing kidney disease.
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However, doctors agree that once albumin starts leaking in the urine and
kidney disease is established, reduction of protein intake slows down the
progression of kidney damage. People with proven kidney disease should
reduce their protein intake after checking with their doctors.
Currently, most health experts recommend a daily intake of 0.8 gram of
protein per 1 kilogram of body weight for men and nonpregnant women.
This much protein will provide enough nutrition to the body, and at the same
time, minimize the risk for kidney disease. Evidence suggests that when the
filtration function of the kidneys begins to fall, a restricted use of protein,
amounting to 0.6 gram per 1 kilogram of body weight, per day, may be
helpful in slowing down further kidney damage.
Use of ACE Inhibitors and ARBs. Angiotensin converting enzyme (ACE)
inhibitors and angiotensin receptor blockers (ARBs) are the drugs of choice
in treatment of diabetic kidney disease. Basically, these are blood pressurelowering
drugs (see chapter 19), but they have been found especially useful
in reducing albumin leakage in the urine, thereby delaying or preventing
progression of diabetic or non-diabetic kidney disease. Because of their
protective effect on the kidneys, these drugs are often prescribed for people
with diabetes who have albumin present in their urine even though they may
not have high blood pressure. ACE inhibitors or ARBs are wonderful drugs,
which when used under medical supervision, help prevent kidney failure.
Timely Treatment of Urinary Infections. Get proper treatment for any
urinary tract infections. When these infections are left untreated, they
increase your risk for kidney damage.
Using Pain Killers Carefully. Be careful in the use of NSAID (nonsteroidal
anti-inflammatory drugs) class of pain killing medications. These
include Ibuprofen (Advil, Motrin), and diclofenac (Voltaren). These drugs
can be harmful to your kidneys.
TREATMENT OF KIDNEY FAILURE. The only treatments available for
kidney failure are dialysis and kidney transplantation.
DIALYSIS. In kidney failure, dialysis is a procedure that artificially
performs the blood cleaning function of the kidneys. Dialysis filters out
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waste substances, extra fluid, and excess salt from the blood, and keeps the
blood chemically balanced. Dialysis is of two kinds: hemodialysis that
cleans the blood through tubes placed outside the body, and peritoneal
dialysis, which cleans the blood inside the body.
Hemodialysis. In hemodialysis, a machine is connected usually in a vein in
your forearm. The blood travels from the body to a filter in the machine that
cleans it. After the blood is cleaned, it is transported back to the body
through another set of tubes. This procedure is done 3 to 4 times a week, and
each procedure lasts 3 to 5 hours. This procedure has some side effects such
as muscle cramps, and fall in blood pressure that makes the patient feel
weak and dizzy. Hemodialysis is the most common form of dialysis; nearly
80 percent of people on dialysis go through this procedure. Hemodialysis is
mostly done in a clinic, but it can be done at home also.
Peritoneal Dialysis. In peritoneal dialysis, blood cleaning is done inside the
body, which you can self-handle. For this procedure, the doctor creates an
access area on your abdomen, through which a special soft tube (catheter)
is placed that goes down into the abdomen. You fill a cleansing solution in
the tube from where it flows in the peritoneum, a membrane that surrounds
the abdominal cavity. The solution, remaining inside the body, absorbs
wastes and extra water from the blood through the peritoneal membrane that
works like a filter. After several hours, you self-drain the used fluid and refill
fresh cleansing solution through the tube, a process called an exchange. You
can self-manage the exchanges at home. Peritoneal dialysis has two
main forms:
Continuous Ambulatory Peritoneal Dialysis (CAPD). This procedure is
called ‘continuous’ because in this method the dialysis goes on continuously
inside the abdomen, day and night. Ambulatory means walking or moving.
CAPD is called ambulatory because in this procedure you are not confined
to bed, but moving and walking and performing your usual daily activities
while the dialysis is going on all the time. In this method of dialysis, the
catheter is placed in the abdomen for long-term use: as a route to self-fill
fresh cleansing solution every 6 hours, and to self-drain the used fluid. For
continuous dialysis, this procedure is repeated four times every day. CAPD
does not require any machine to be used.
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Automated Peritoneal Dialysis (APD). This procedure is the same as
CAPD except that it requires a machine to drain used fluids and replace
fresh solutions during the night. When going to bed, you connect the
machine to your catheter. The machine performs fluid exchanges, cleansing
the blood wastes throughout the night. Overnight blood cleansing in this
procedure will make you free from the need of dialysis most of the day.
The peritoneal dialysis procedure may sometimes develop complications
such as infection at the site where the tube is inserted, fever, and
abdominal pain.
KIDNEY TRANSPLANTATION. In kidney transplantation, a healthy kidney
from another person is surgically transplanted in a person whose kidneys
have failed. The transplanted kidney takes over the filtration function lost by
the failed kidneys. Often, the kidney and the pancreas are transplanted
together. The combined transplantation makes the patient free from the need
of dialysis and insulin injections.
The person who receives a kidney transplant is called a recipient. The
person whose kidney is transplanted is called a donor. There may be three
kinds of donors: a live related donor who can be a parent, brother or sister;
a living unrelated donor who can be a spouse or a close friend of the patient;
and a cadaver donor who is a person who has recently died. In kidney transplantation,
tissue and blood matching is absolutely essential or the body will
reject the transplanted kidney as a foreign body. Living relatives are the best
candidates as kidney donors because their kidneys are more likely to be
compatible than the kidneys of unrelated or dead donors. A person can
donate a kidney without much harm to his or her own kidney function since
one healthy kidney is sufficient for healthy living.
Statistics show that 1 year after kidney transplantation about 95 percent
of the recipients remain alive. The survival rate after 5 years of kidney
transplantation has been about 80 percent. Kidney transplantation, thus,
offers a better survival rate than dialysis in which only 30 percent of the
people receiving dialysis remained alive after 5 years.
Kidney transplantation, however, has its own complications. There is
always a risk that the body may reject the transplanted kidney as a foreign
body however compatible the kidney may be. To suppress reaction of the
body against a transplanted kidney, anti-rejection drugs called immunosuppressants,
are taken by a kidney recipient on a regular basis throughout life.
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These anti-rejection drugs, in the long term, are likely to have serious side
effects such as damage to the body’s immune system (infection fighting
system), liver injury, and harm to the transplanted kidney. In addition, there
is always a chance that the anti-rejection drugs may fail in their action, and
the body may reject the transplanted kidney. Such a condition may create a
need for another transplantation.
To prevent kidney damage from diabetes and to avoid dialysis and
kidney transplantation, your best defense is to keep your blood sugar and
blood pressure under control. Well conducted studies have clearly shown
that strict control of blood sugar and blood pressure in people with diabetes
significantly reduces their risk for kidney damage, and helps prevent
kidney failure.