Kidney Failure

GLOSSARY 

U.S. Department 

of Health and

Human Services

NATIONAL INSTITUTES OF HEALTH

National Kidney and Urologic Diseases

Information Clearinghouse
Kidney Failure

GLOSSARY

NATIONAL INSTITUTES OF HEALTH

National Institute of Diabetes and Digestive and Kidney Diseases
1

Introduction

This glossary defines words that are often used when people

talk or write about kidney failure and its treatments. It is

designed for people whose kidneys have failed and for their

families and friends.

The words are listed in alphabetical order. Some words have

many meanings; only those meanings that relate to kidney

diseases are included. Words that appear in bold italic are

defined elsewhere in the glossary. A term will refer the reader

to another definition only when the second definition gives

additional information about the topic that is directly related

to the first term.

A

access: In dialysis, the point on the body where a needle or

catheter is inserted. (See also arteriovenous fistula, graft,

and vascular access.)

acute renal (REE-nul) failure: Sudden and temporary loss of

kidney function. (See also chronic kidney disease.)

allograft (AL-oh-graft): An organ or tissue transplant from

one human to another. 

amyloidosis (AM-ih-loy-DOH-sis): A condition in which a

protein-like material builds up in one or more organs. This

material cannot be broken down and interferes with the

normal function of that organ. People who have been on

dialysis for several years often develop amyloidosis because

the artificial membranes used in dialysis fail to filter the

protein-like material out of the blood.
2

anemia (uh-NEE-mee-uh): The condition of having too few

red blood cells. Healthy red blood cells carry oxygen

throughout the body. If the blood is low on red blood

cells, the body does not get enough oxygen. People with

anemia may be tired and pale and may feel their heartbeat

change. Anemia is common in people with chronic kidney

disease or those on dialysis. (See also erythropoietin.) 

anuria (uh-NYOOR-ee-uh): A condition in which a person

stops making urine.

arterial (ar-TEER-ee-ul) line: In hemodialysis (see dialysis),

tubing that takes blood from the body to the dialyzer.

arteriovenous (ar-TEER-eeoh-VEE-nus) (AV) fistula

(FIST-yoo-lah): Surgical

connection of an artery

directly to a vein, usually

in the forearm, created in

patients who will need

hemodialysis (see dialysis).

The AV fistula causes the

vein to grow thicker, allowing the repeated needle

insertions required for

hemodialysis. 

artery (AR-ter-ee): A blood vessel that carries blood away

from the heart to the body. (See also vein.)

artificial kidney: Another name for a dialyzer.

autoimmune (aw-toh-ih-MYOON) disease: A disease that

occurs when the body’s immune system mistakenly attacks

the body itself. 

Arteriovenous fistula.

From

dialysis

machine

To

dialysis

machine
3

B

biopsy (BY-op-see): A procedure in which a tiny piece of a

body part, such as the kidney or bladder, is removed for

examination under a microscope. 

bladder: The balloon-shaped organ inside the pelvis that

holds urine.

blood urea (yoo-REE-uh) nitrogen (NY-truh-jen) (BUN): A

waste product in the blood that comes from the breakdown

of food protein. The kidneys filter blood to remove urea.

As kidney function decreases, the BUN level increases. 

C

catheter (KATH-eh-ter): A tube inserted through the skin

into a blood vessel or cavity to draw out body fluid or

infuse fluid. In peritoneal dialysis (see dialysis), a catheter

is used to infuse dialysis solution into the abdominal cavity

and drain it out again. 

Two double-cuff Tenckhoff peritoneal catheters: standard (A), curled (B).

A

B

Subcutaneous

cuff

Peritoneal

cuff

Peritoneal cavity

Outer

skin

Peritoneal cavity

Subcutaneous

cuff

Peritoneal

cuff

Outer

skin
4

chronic kidney disease: Slow and progressive loss of kidney

function over several years, often resulting in permanent

kidney failure. People with permanent kidney failure need

dialysis or transplantation (see transplant) to replace the

work of the kidneys. 

creatinine (kree-AT-ih-nin): A waste product from meat

protein in the diet and from the muscles of the body.

Creatinine is removed from blood by the kidneys; as

kidney disease progresses, the level of creatinine in the

blood increases. 

creatinine clearance: A test that measures how efficiently

the kidneys remove creatinine and other wastes from

the blood. Low creatinine clearance indicates impaired

kidney function. 

cross-matching: Before a transplant, the donor’s blood is

tested with the recipient’s blood to see whether they

are compatible.

D

diabetes (dy-uh-BEE-teez) mellitus (MELL-ih-tus): A condition characterized by high blood glucose (sugar) resulting

from the body’s inability to use glucose efficiently. Insulin

normally helps the body’s cells use glucose. In type 1 diabetes, the pancreas makes little or no insulin; in type 2

diabetes, the body is resistant to the effects of available

insulin.

dialysis (dy-AL-ih-sis): The process of cleaning wastes from

the blood artificially. This job is normally done by the

kidneys. If the kidneys fail, the blood must be cleaned

artificially with special equipment. The two major forms

of dialysis are hemodialysis and peritoneal dialysis.
• hemodialysis (HEE-moh-dy-AL-ih-sis): The use of

a machine to clean wastes from the blood after the

kidneys have failed. The blood travels through tubes

to a dialyzer, which removes wastes and extra fluid.

The cleaned blood then flows through another set of

tubes back into the body.

• peritoneal (PEH-rih-tuh-NEE-ul) dialysis: Cleaning

the blood by using the lining of the abdominal cavity

as a filter. A cleansing liquid, called dialysis solution,

is drained from a bag into the abdomen. Fluids and

wastes flow through the lining of the cavity and remain

“trapped” in the dialysis solution. The solution is then

drained from the abdomen, removing the extra fluids

and wastes from the body. There are two main types

of peritoneal dialysis: 

– continuous ambulatory (AM-byoo-luh-TOH-ree)

peritoneal dialysis (CAPD): The most common type

5

Hemodialysis.

Heparin pump

(to prevent

clotting)

Dialyzer inflow

pressure monitor

Dialyzer

Arterial

pressure monitor

Blood pump

Blood removed

for cleansing

Clean blood

returned to

body

Air detector

clamp

Air trap and

air detector

Venous 

pressure monitor
6

of peritoneal dialysis. It needs no machine. With

CAPD, the blood is always being cleaned. The

dialysis solution passes from a plastic bag through

the catheter and into the abdomen. The solution

stays in the abdomen with the catheter sealed. After

several hours, the person using CAPD drains the solution back into a disposable bag. Then the person

refills the abdomen with fresh solution through the

same catheter, to begin the cleaning process again. 

– continuous cycling peritoneal dialysis (CCPD):

A form of peritoneal dialysis that uses a machine.

This machine automatically fills and drains the dialysis solution from the abdomen. A typical CCPD

schedule involves three to five exchanges during the

night while the person sleeps. During the day, the

person using CCPD performs one exchange with a

dwell time that lasts the entire day. 

dialysis solution: A cleansing

liquid used in the two

major forms of dialysis—

hemodialysis and peritoneal

dialysis. Dialysis solution

contains dextrose (a sugar)

and other chemicals similar

to those in the body.

Dextrose draws wastes and

extra fluid from the body

into the dialysis solution. 

dialyzer (DY-uh-LY-zur): A

part of the hemodialysis

machine. (See dialysis.)

The dialyzer has two

sections separated by a

membrane. One section

Header

Solution

outlet

Fibers

Jacket

Solution

inlet

Blood outlet

Blood inlet

Tube sheet

Structure of a typical hollow fiber dialyzer.
7

holds dialysis solution. The other holds the patient’s

blood. 

donor: A person who offers blood, tissue, or an organ for

transplantation. (See transplant.) In kidney transplantation, the donor may be someone who has just died or

someone who is still alive, usually a relative.

dry weight: The ideal weight for a person after a hemodialysis (see dialysis) treatment. The weight at which a

person’s blood pressure is normal and no swelling exists

because all excess fluid has been removed.

dwell time: In peritoneal dialysis (see dialysis), the amount

of time a bag of dialysis solution remains in the patient’s

abdominal cavity during an exchange.

E

edema (eh-DEE-muh): Swelling caused by too much fluid in

the body. 

electrolytes (ee-LEK-troh-lites): Chemicals in the body fluids

that result from the breakdown of salts, including sodium,

potassium, magnesium, and chloride. The kidneys control

the amount of electrolytes in the body. When the kidneys

fail, electrolytes get out of balance, causing potentially serious health problems. Dialysis can correct this problem. 

end-stage renal (REE-nul) disease (ESRD): Total and permanent kidney failure. When the kidneys fail, the body

retains fluid and harmful wastes build up. A person with

ESRD needs treatment to replace the work of the failed

kidneys. 

erythropoietin (eh-RITH-roh-POY-uh-tin): A hormone made

by the kidneys to help form red blood cells. Lack of this

hormone may lead to anemia.
8

ESRD: See end-stage renal disease.

exchange: In peritoneal dialysis (see dialysis), the draining

of used dialysis solution from the abdomen, followed by

refilling with a fresh bag of solution. 

F

fistula (FIST-yoo-lah): See arteriovenous fistula.

G

glomeruli (gloh-MEHR-yoo-lie): Plural of glomerulus.

glomerulonephritis (gloh-MEHR-yoo-loh-nef-RY-tis):

Inflammation of the glomeruli. Most often, it is caused

by an autoimmune disease, but it can also result from

infection. 

glomerulosclerosis (gloh-MEHRyoo-loh-skleh-ROH-sis):

Scarring of the glomeruli.

It may result from diabetes

mellitus (diabetic glomerulosclerosis) or from deposits in

parts of the glomeruli (focal

segmental glomerulosclerosis).

The most common signs of

glomerulosclerosis are

proteinuria and kidney failure. 

glomerulus (gloh-MEHR-yoo-lus):

A tiny set of looping blood

vessels in the nephron where

blood is filtered in the kidney. Glomerulus.

Glomerulus

Tubule

Nephron
9

graft: In hemodialysis (see dialysis), a vascular access surgically created using a synthetic tube to connect an artery to

a vein. In transplantation (see transplant), a graft is the

transplanted organ or tissue.

H

hematocrit (hee-MAT-uh-krit): A measure that tells what portion of a blood sample consists of red blood cells. Low

hematocrit suggests anemia or massive blood loss. 

hematuria (HEE-muh-TOO-ree-uh): A condition in which

urine contains blood or red blood cells.

hemodialysis: See dialysis.

hormone: A natural chemical produced in one part of the

body and released into the blood to trigger or regulate particular functions of the body. The kidney releases three

hormones: erythropoietin, renin, and an active form of

vitamin D that helps regulate calcium for bones. 

hypertension (HY-per-TEN-shun): High blood pressure,

which can be caused either by too much fluid in the blood

vessels or by narrowing of the blood vessels. 

Graft.

Looped graft

Vein

Artery
10

I

immune (ih-MYOON) system: The body’s system for protecting itself from viruses and bacteria or any “foreign”

substances. 

immunosuppressant (ih-MYOON-oh-suh-PRESS-unt): A

drug given to suppress the natural responses of the body’s

immune system. Immunosuppressants are given to

transplant patients to prevent organ rejection and to

patients with autoimmune diseases like lupus. 

interstitial (IN-ter-STISH-ul) nephritis (nef-RY-tis):

Inflammation of the kidney cells that are not part of the

fluid-collecting units, a condition that can lead to acute

renal failure or chronic kidney disease.

intravenous (IN-truh-VEE-nus) pyelogram (PY-loh-gram):

An x ray of the urinary tract. A dye is injected to make

the kidneys, ureters, and bladder visible on the x ray and

show any blockage in the urinary tract.

K

kidney: One of two bean-shaped organs that filter wastes

from the blood. The kidneys are located near the middle

of the back. They create urine, which is delivered to the

bladder through tubes called ureters.

kidney failure: Loss of kidney function. (See also end-stage

renal disease, acute renal failure, and chronic kidney

disease.)

Kt/V (kay-tee over vee): A measurement of dialysis dose.

The measurement takes into account the efficiency of the

dialyzer, the treatment time, and the total volume of urea

in the body. (See also URR.) 
11

M

membrane: A thin sheet or layer of tissue that lines a cavity

or separates two parts of the body. A membrane can act as

a filter, allowing some particles to pass from one part of

the body to another while keeping others where they are.

The artificial membrane in a dialyzer filters waste products

from the blood. 

membranoproliferative (MEM-bray-no-pro-LIF-er-uh-tiv)

glomerulonephritis (gloh-MEHR-yoo-loh-nef-RY-tis): A

disease that occurs primarily in children and young adults.

Over time, inflammation leads to scarring in the glomeruli,

causing proteinuria, hematuria, and sometimes chronic

kidney disease or end-stage renal disease.

N

nephrectomy (nef-REK-tuh-mee): Surgical removal of a

kidney.

nephrologist (nef-RAHL-oh-jist): A doctor who treats

patients with kidney problems or hypertension.

nephron (NEF-rahn): A tiny part of the kidneys. Each kidney is made up of about 1 million nephrons, which are the

working units of the kidneys, removing wastes and extra

fluids from the blood. 

nephrotic (nef-RAH-tik) syndrome: A collection of symptoms

that indicate kidney damage. Symptoms include high levels

of protein in the urine, lack of protein in the blood, and

high blood cholesterol. 

nuclear (NEW-klee-ur) scan: A test of the structure, blood

flow, and function of the kidneys. The doctor injects a

mildly radioactive solution into an arm vein and uses x rays

to monitor its progress through the kidneys. 
12

P

peritoneal (PEH-rih-tuh-NEE-ul) cavity: The space inside the

lower abdomen but outside the internal organs.

peritoneal dialysis: See dialysis.

peritoneum (PEH-rih-tuh-NEE-um): The membrane lining

the peritoneal cavity.

peritonitis (PEH-rih-tuh-NY-tis): Inflammation of the

peritoneum, a common complication of peritoneal dialysis

(see dialysis).

potassium (puh-TASS-ee-um): A mineral found in the body

and in many foods. 

proteinuria (PRO-tee-NOOR-ee-uh): A condition in which

the urine contains large amounts of protein, a sign that the

kidneys are not functioning properly.

R

renal (REE-nul): Of the kidneys. A renal disease is a disease

of the kidneys. Renal failure means the kidneys have

stopped working properly.

renal osteodystrophy (AH-stee-oh-DIS-truh-fee): Weak bones

caused by poorly working kidneys. Renal osteodystrophy

is a common problem for people on dialysis who have high

phosphate levels or insufficient vitamin D supplementation. 

renin (REE-nin): A hormone made by the kidneys that

helps regulate the volume of fluid in the body and blood

pressure. 

S

sodium (SOH-dee-um): A mineral found in the body and in

many foods. 
13

T

thrill: A vibration or buzz that can be felt in an arteriovenous

fistula, an indication that the fistula is healthy.

transplant: Replacement of a diseased organ with a healthy

one. A kidney transplant may come from a living donor,

usually a relative, or from someone who has just died. 

U

urea (yoo-REE-uh): A waste product found in the blood and

caused by the normal breakdown of protein in the liver.

Urea is normally removed from the blood by the kidneys

and then excreted in the urine. Urea accumulates in the

body of people with renal failure. 

uremia (yoo-REE-mee-uh): The illness associated with the

buildup of urea in the blood because the kidneys are not

working effectively. Symptoms include nausea, vomiting,

loss of appetite, weakness, and mental confusion. 

ureters (YOOR-uh-turs): Tubes that carry urine from the

kidneys to the bladder.

urethra (yoo-REE-thrah): The tube that carries urine from

the bladder to the outside of the body. 

urinalysis (yoor-in-AL-ih-sis): A test of a urine sample that

can reveal many problems of the urinary system and other

body systems. The sample may be observed for color,

cloudiness, and concentration; signs of drug use; chemical

composition, including sugar; the presence of protein,

blood cells, or germs; or other signs of disease. 
14

urinary (YOOR-ih-NEHR-ee)

tract: The system that takes

wastes from the blood and

carries them out of the

body in the form of urine.

The urinary tract includes

the kidneys, renal pelvises,

ureters, bladder, and

urethra.

urinate (YOOR-ih-nate):

To release urine from the

bladder to the outside. 

urine (YOOR-in): Liquid

waste product filtered from

the blood by the kidneys,

stored in the bladder, and

expelled from the body

through the urethra by the act of voiding or urinating.

(See also urinate.) 

URR (urea reduction ratio): A blood test that compares the

amount of blood urea nitrogen before and after dialysis to

measure the effectiveness of the dialysis dose. 

V

vascular (VASS-kyoo-lur) access: A general term to describe

the area on the body where blood is drawn for circulation

through a hemodialysis (see dialysis) circuit. A vascular

access may be an arteriovenous fistula, a graft, or a

catheter.

vein (VANE): A blood vessel that carries blood toward the

heart.

venous (VEE-nus) line: In hemodialysis (see dialysis), tubing

that carries blood from the dialyzer back to the body.

Urinary tract.

Urethra

Kidneys

Ureter

Bladder Renal

pelvises
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This booklet is also available at www.kidney.niddk.nih.gov.
National Institute of Diabetes and Digestive and Kidney Diseases

NIH Publication No. 03–4894

April 2003

U.S. Department of Health and Human Services

National Institutes of Health