Diabetes and Your Kidneys

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Diabetes and Your Kidneys

Written by:

Barbara Casazza, RN-C, FNP, CDE - Weill Medical College of Cornell

University, New York

Introduction

How Does Diabetes Affect the Kidneys?

How are Kidney Problems Diagnosed?

Minimizing Damage to the Kidneys

Dialysis for End-Stage Renal Disease

Kidney Transplantation

Summary

Introduction

There are approximately 15.7 million Americans with diabetes in the

United States, of which 10.3 million are diagnosed and 5.4 million

are not yet diagnosed. These include people with both insulin

dependent (Type 1) and non-insulin dependent (Type 2) diabetes.

Diabetes is the fourth leading cause of death in the United States

and is associated with many complications, including blindness in

adults, end-stage renal (kidney) disease and non-traumatic

amputation. In 1996, there were 30,000 new diagnosed cases of end-

stage renal disease resulting from diabetes. Unfortunately, we can

only expect this number to increase.

There are, however, a number of ways to diagnose early problems in

kidney function, and a number of treatment options for those with

renal disease. This article will explore some of these diagnostic and

treatment alternatives.

How Does Diabetes Affect the Kidneys?

Renal disease can take many forms, from mild impairment of kidney

function, (renal insufficiency) to kidney failure (end-stage renal

disease) requiring dialysis (cleaning the blood). First, it is

important to understand what these small, bean-shaped organs actually

do.

It is the kidney's job to:

regulate fluid and electrolyte (e.g. sodium, potassium, chloride,

etc.) balance

control blood pressure

produce hormones

remove waste products

Diabetes affects the smallest blood vessels in the body called

capillaries. High blood glucose levels found in diabetic patients

cause a number of biochemical changes in these blood vessels making

them `leaky'. In the kidneys, these changes in the capillaries are

thought to occur over a period of ten years or longer and result in

multiple problems with the kidneys. As with all complications related

to diabetes, good glucose control can limit the amount of damage

caused by the disease. Still, no matter how well the glucose levels

are controlled, renal function should be monitored in a person with

diabetes.

How are Kidney Problems Diagnosed?

Blood tests and a number of urine tests help doctors to arrive at a

diagnosis.

Blood Tests

The standard blood tests that monitor renal function are the BUN

(blood urea nitrogen) and creatinine. These proteins are markers of

renal function, i.e. indicators of how well the kidneys are clearing

waste products from the blood.

Urine Tests

In addition to these blood tests, people with diabetes should also

have urine testing done. The initial test should be a routine

urinalysis for the detection of protein in the urine. Normal kidneys

do not `leak out' protein, so finding protein in the urine is an

indication that something is wrong with your kidneys. If this test is

positive, further urine testing (for example: a 24-hour urine

collection) should be done to determine the total amount of protein

lost by the kidneys during a 24-hour period. If the 24-hour urine

samples reveal that large amounts of protein are being lost in the

urine, the patient should be referred to a kidney specialist

(nephrologist) for further testing and treatment.

If the routine urinalysis is negative and no protein is found in the

urine, then a more sensitive test of the urine should be done. This

test looks for very small amounts of albumin (a normal protein found

in the blood). The early effects of diabetes in the kidney may result

in minute amounts of protein leaking out in the urine. By searching

for small amounts of albumin in the urine (microalbuminuria), your

doctor can evaluate if you have early damage to your kidneys.

Minimizing Damage to the Kidneys

There are a number of ways to minimize damage to the kidneys,

including medical treatments, and attention to diet and lifestyle

choices.

ACE inhibitors

It has recently been recognized that medications can be used to

protect the kidneys from further damage. ACE inhibitors (angiotensin

converting enzyme inhibitors) are pills that, along with lowering

blood pressure, also help to normalize kidney function in diabetic

patients. It is important to remember that urine albumin should

continue to be monitored while you are on an ACE inhibitor. If the

urine albumin ever increases, your doctor can increase the dosage of

the ACE inhibitor to compensate.

ACE inhibitor side-effects

One common side effect of ACE inhibitors is a slight cough. If this

cough does not stop after several weeks, your healthcare provider

could try a different ACE inhibitor. Other side effects include

swelling, rash, or a bad taste in the mouth. You should report any

strange sensations to your provider. Finally, ACE inhibitors should

never be used during pregnancy – they are associated with a variety

of fetal abnormalities.

Other ways to minimize kidney damage

There are a number of additional ways for people with diabetes to

minimize kidney damage, even for those using ACE inhibitors. Diet,

weight loss, exercise and medication for diabetes continue to be

important. Every effort should be made to maintain normal blood

glucose levels and good blood pressure control. Additionally,

cigarette smoking should be avoided. If you are a smoker, a smoking

cessation program should be a mandatory part of your diabetes

management.

What happens if the kidneys continue to leak protein?

Despite the use of an ACE inhibitor, if the kidney disease continues

to progress and the amount of protein leaked by the kidneys continues

to increase, there are other available interventions.

It is thought that a protein-restricted diet reduces the workload on

the kidneys and aids in the preservation of renal function.

Monitoring the amount of phosphate in the diet is also an important

tool in kidney maintenance. Aggressive blood pressure control with

ACE inhibitors and other antihypertensive agents should continue. It

should also be remembered that radiocontrast material (the

intravenous `dye' used in many radiographic studies, e.g. some CAT

scans) can exacerbate kidney problems and should be used only after

careful evaluation.

Dialysis for End-Stage Renal Disease

If kidney impairment progresses to end-stage renal disease (renal

failure), treatment options still exist. Glucose and blood pressure

control continue to be important in the management of the disease. In

addition, the use of dialysis (either hemodialysis or peritoneal

dialysis) helps to control the symptoms of renal failure, such as

loss of appetite, nausea, vomiting, shortness of breath, edema,

difficulty sleeping and generalized itchiness.

Dialysis is a process whereby the blood's waste products, normally

eliminated through the kidneys, are removed in other ways. You can

think of this as `cleaning' the blood. There are two different types

of dialysis that are used in the treatment of end-stage renal

failure: hemodialysis, and peritoneal dialysis.

Hemodialysis

Hemodialysis is a method that requires filtering blood through a

dialysis machine. However, before hemodialysis can start, a vascular

access (a place to access blood flow in the body) must be created.

This usually requires a minor surgical procedure and can be done in

two ways. In the first method, a piece of gore-tex (or some other

artificial tubing-like material) is placed under the skin joining an

artery to a vein (often in the forearm). This is called a graft. In

the second method, called a fistula, an artery may be joined directly

to a vein without the use of tubing. Both procedures create areas of

high blood flow close to the surface of the skin.

During hemodialysis, needles are placed in the access area and blood

passes through tubing to a filter machine that removes the waste

products. This treatment takes three to four hours and usually occurs

at a dialysis center two or three days a week.

Peritoneal dialysis

Peritoneal dialysis is a form of treatment that does not involve any

blood or needles. Instead, a small surgical procedure is done in the

abdominal area, and a soft piece of plastic tubing is implanted into

the peritoneal space (behind the abdominal muscle wall and in front

of the abdominal organs). This tubing is approximately 4 to 5 inches

in length and remains sticking out of the abdomen. A dialysis

solution runs into the peritoneal cavity through this soft plastic

tubing and remains in the cavity for a prescribed period of time,

after which it is drained out. This is repeated multiple times a day

(usually 4 to 5) and requires a sterile technique to avoid infection.

Peritoneal dialysis is usually successful with motivated patients who

are able to undergo a training program to learn the dialysis

procedure. After the training, patients are free to dialyze

independently at home.

How long is dialysis necessary?

When kidneys fail due to chronic disease such as diabetes, dialysis

treatment usually becomes lifetime therapy. Still, it is because of

dialysis treatment that patients can continue to work, travel, attend

school, and generally carry on with their usual activity schedule.

Once kidneys fail, waste products build up in the blood and cause

symptoms such as nausea, vomiting, and shortness of breath. Dialysis

can alleviate these symptoms and allow for a better quality of life.

Kidney Transplantation

Kidney transplantation is an option for a patient with end-stage

renal disease resulting from diabetes. Prior to being considered for

a renal transplant, extensive medical testing, including a cardiac

evaluation, is done to assure a good outcome.

Summary

Diabetes, the fourth leading cause of death in the United States, is

associated with many complications, including kidney damage and

failure. Aggressive glucose control, along with blood pressure

control and the avoidance of smoking, can help in the prevention of

diabetic complications. Monitoring of urine for trace amounts of

albumin can help detect kidney damage early and allow intervention

with ACE inhibitors to slow the progression of diabetic renal disease

and preserve renal function. Should renal function fail, treatment

options include hemodialysis, peritoneal dialysis, and renal

transplantation.