National Kidney and Urologic Diseases Information Clearinghouse
of Health and
National Kidney and Urologic Diseases
NATIONAL INSTITUTES OF HEALTH Information Clearinghouse
Kidney Diseases Dictionary
This dictionary deﬁnes words that are often used when people talk or write
about kidney diseases. It is designed for people who have kidney diseases and
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 dictionary. A term will
refer the reader to another deﬁnition only when the second deﬁnition gives
additional information about a topic that is directly related to the ﬁrst term.
This information is not a substitute for a visit to your doctor. Talk to a health
professional if you have a kidney problem.
of Health and
National Kidney and Urologic Diseases
NATIONAL INSTITUTES OF HEALTH Information Clearinghouse
acute (uh-KYOOT): Acute often as well as hearing and vision
means urgent. An acute disease problems. The common symptoms
happens suddenly. It lasts a short of this condition are chronic blood
time. Acute is the opposite of and protein in the urine.
chronic, or long lasting.
acute renal (REE-nul) failure: A condition in which a protein-like
Sudden and temporary loss of material builds up in one or more
kidney function. (See also chronic organs. This material cannot be
kidney disease.) broken down and interferes with
the normal function of that organ.
acute tubular (TOO-byoo-lur)
In kidneys, amyloidosis can lead
necrosis (neh-KRO-sis) (ATN):
to proteinuria, nephrotic syndrome,
A severe form of acute renal failure
and kidney failure.
that develops in people with
severe illnesses like infections or analgesic (AN-ul-JEE-zik)
with low blood pressure. Patients associated kidney disease: Loss
may need dialysis. Kidney function of kidney function that results
often improves if the underlying from long-term use of analgesic
disease is successfully treated. (pain-relieving) medications.
Analgesics that combine aspirin
and acetaminophen are most
ree-uh): More than normal
dangerous to the kidneys.
amounts of a protein called
albumin in the urine. Albuminuria anemia (uh-NEE-mee-uh): The
may be a sign of kidney disease. condition of having too few red
blood cells. Healthy red blood
allograft (AL-oh-graft): An organ or
cells carry oxygen throughout the
tissue transplant from one human
body. If the blood is low on red
blood cells, the body does not
Alport syndrome (AL-port SIN get enough oxygen. People with
drome): An inherited condition anemia may be tired and pale and
that results in kidney disease. It may feel their heartbeat change.
generally develops during early Anemia is common in people with
childhood and is more serious in chronic kidney disease or those on
boys than in girls. The condition dialysis. (See also erythropoietin.)
can lead to end-stage renal disease,
antidiuretic (AN-tee-DY-uh-RET-ik) (see dialysis). The AV ﬁstula
hormone (ADH): A natural body causes the vein to grow
chemical that slows down the urine thicker, allowing the repeated
ﬂow. Some children who wet their needle insertions required for
beds regularly may lack normal hemodialysis.
amounts of antidiuretic hormone.
anuria (uh-NYOOR-ee-uh): A disease: Any disorder in which
condition in which the person the body is attacked by its own
stops making urine. immune system. Examples are
Goodpasture syndrome and
lupus erythematosus (see lupus
nus) (AV) ﬁstula (FIST-yoo-luh):
Surgical connection of an artery
directly to a vein, usually in the biopsy (BY-op-see): A procedure in
forearm, created in patients which a tiny piece of a body part,
who will need hemodialysis such as the kidney or bladder, is
removed for examination under a
dialysis bladder (BLAD-ur): The balloon-
machine shaped organ inside the pelvis that
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
To function decreases, the BUN level
calcium (KAL-see-um): A mineral
that the body needs for strong
bones and teeth. Calcium may
form stones in the kidney.
chronic (KRAH-nik): Lasting a long creatinine clearance: A test that
time. Chronic diseases develop measures how efﬁciently the
slowly. Chronic kidney disease may kidneys remove creatinine and
develop over many years and lead other wastes from the blood. Low
to end-stage renal disease. creatinine clearance indicates
impaired kidney function.
chronic kidney disease (CKD): Any
condition that causes reduced cyst (SIST): An abnormal sac
kidney function over a period containing gas, ﬂuid, or a
of time. CKD is present when a semisolid material. Cysts may
patient’s glomerular ﬁltration rate form in kidneys or in other parts of
remains below 60 mL/min/1.73 m2 the body. (See also renal cysts.)
for more than 3 months.
cystine (SIS-teen): An amino acid
congenital (kun-JEN-ih-tul) nephrotic found in blood and urine. Amino
(nef-RAH-tik) syndrome: A acids are building blocks of
genetic kidney disease that protein. (See also cystine stone
develops before birth or in the ﬁrst and cystinuria.)
few months of life. Congenital
cystine stone: A rare form of kidney
nephrotic syndrome usually leads
stone consisting of the amino acid
to end-stage renal disease and
the need for dialysis or a kidney
transplant by the second or third cystinuria (SIS-tih-NOO-ree-uh):
year of life. A condition in which urine
contains high levels of the amino
creatinine (kree-AT-ih-nin): A waste
acid cystine. If cystine does not
product from meat protein in the
dissolve in the urine, it can build
diet and from the muscles of the
up to form kidney stones.
body. Creatinine is removed from
blood by the kidneys; as kidney cystitis (sis-TY-tis): Inﬂammation
disease progresses, the level of of the bladder, causing pain and
creatinine in the blood increases. a burning feeling in the pelvis or
cystoscope (SIS-tuh-skope): A tool
for examining the bladder. The
procedure is called cystoscopy (sis
diabetes (dy-uh-BEE-teez) insipidus in type 2 diabetes, the body is
(in-SIP-ih-dus): A condition resistant to the effects of available
characterized by frequent and insulin.
heavy urination, excessive thirst,
dialysis (dy-AL-ih-sis): The process
and an overall feeling of weakness.
of cleaning wastes from the blood
This condition may be caused by a
artiﬁcially. This job is normally
defect in the pituitary gland or in
done by the kidneys. If the
the kidney. In diabetes insipidus,
kidneys fail, the blood must be
blood glucose levels are normal.
cleaned artiﬁcially with special
(See also nephrogenic diabetes
equipment. The two major forms
of dialysis are hemodialysis and
diabetes (dy-uh-BEE-teez) mellitus peritoneal dialysis.
(MELL-ih-tus): A condition
● hemodialysis (HEE-moh-dy-AL
characterized by high blood
glucose (sugar) resulting from ih-sis): The use of a machine
the body’s inability to use glucose to clean wastes from the blood
efﬁciently. In type 1 diabetes, the after the kidneys have failed.
pancreas makes little or no insulin; The blood travels through
pressure monitor Venous
Dialyzer Air trap and
pressure monitor Clean blood
returned to body
Blood removed for
tubes to a dialyzer, which abdomen with the catheter
removes wastes and extra ﬂuid. sealed. After several hours,
The cleaned blood then ﬂows the person using CAPD
through another set of tubes drains the solution back into
back into the body. a disposable bag. Then the
person reﬁlls the abdomen
● peritoneal (PEH-rih-tuh with fresh solution through
NEE-ul) dialysis: Cleaning the same catheter, to begin
the blood by using the lining the cleaning process again.
of the belly (abdomen) as a
ﬁlter. A cleansing solution, • continuous cycling peritoneal
called dialysis solution, is dialysis (CCPD): A form of
peritoneal dialysis that uses
drained from a bag into the
a machine. This machine
belly. Fluids and wastes ﬂow
automatically ﬁlls and drains
through the lining of the belly
the dialysis solution from the
and remain “trapped” in the abdomen. A typical CCPD
dialysis solution. The solution schedule involves three to
is then drained from the belly, ﬁve exchanges during the
removing the extra ﬂuids and night while the person sleeps.
wastes from the body. There During the day, the person
are three types of peritoneal using CCPD performs one
dialysis: exchange with a dwell time that
• continuous ambulatory lasts the entire day.
(AM-byoo-luh-TOH-ree) • nocturnal (nok-TURN-ul)
peritoneal dialysis (CAPD): intermittent (IN-ter-MIT
The most common type unt) peritoneal dialysis
of peritoneal dialysis. It (NIPD): A machine-aided
needs no machine. With form of peritoneal dialysis.
CAPD, the blood is always NIPD differs from CCPD
being cleaned. The dialysis in that six or more exchanges
solution passes from a plastic take place during the night,
bag through the catheter and the NIPD patient does
and into the abdomen. The not perform an exchange
dialysis solution stays in the during the day.
dialysis solution: A cleansing liquid edema (eh-DEE-muh): Swelling
used in the two major forms caused by too much ﬂuid in the
of dialysis—hemodialysis and body.
peritoneal dialysis. Dialysis
solution contains dextrose (a
Chemicals in the body ﬂuids that
sugar) and other chemicals similar
result from the breakdown of
to those in the body. Dextrose
salts, including sodium, potassium,
draws wastes and extra ﬂuid from
magnesium, and chloride. The
the body into the dialysis solution.
kidneys control the amount of
dialyzer (DY-uh-LY-zur): A part of electrolytes in the body. When
the hemodialysis machine. (See the kidneys fail, electrolytes get
hemodialysis under dialysis.) out of balance, causing potentially
The dialyzer has two sections serious health problems. Dialysis
separated by a membrane. One can correct this problem.
section holds dialysis solution. The
end-stage renal (REE-nul) disease
other holds the patient’s blood.
(ESRD): Total chronic kidney
Blood failure. When the kidneys fail,
patient the body retains ﬂuid and harmful
wastes build up. A person with
ESRD needs treatment to replace
the work of the failed kidneys.
uh-tin): A hormone made by the
kidneys to help form red blood
from cells. Lack of this hormone may
to patient lead to anemia.
ESRD: See end-stage renal disease.
Dialyzer ESWL: See extracorporeal shockwave
dwell time: In peritoneal dialysis, the
amount of time a bag of dialysis
solution remains in the patient’s
abdominal cavity during an
exchange: A cycle in peritoneal glomeruli (gloh-MEHR-yoo-lie):
dialysis in which the patient ﬁlls Plural of glomerulus.
the abdominal cavity with dialysis
solution, carries it for a speciﬁed
dwell time, and then empties it
of the glomeruli. Most often, it is
from the abdomen in preparation
caused by an autoimmune disease,
for a fresh bag of dialysis solution.
but it can also result from infection.
ee-ul) shockwave lithotripsy
(LITH-oh-TRIP-see) (ESWL): A
Scarring of the glomeruli. It
nonsurgical procedure using shock
may result from diabetes mellitus
waves to break up kidney stones.
ﬁstula (FIST-yoo-lah): See or from deposits in parts of
arteriovenous ﬁstula. the glomeruli (focal segmental
most common signs of
ﬁltration rate (GFR): A calculation
glomerulosclerosis are proteinuria
of how efﬁciently the kidneys are
and chronic kidney disease.
ﬁltering wastes from the blood.
A traditional GFR calculation glomerulus (gloh-MEHR-yoo-lus): A
requires an injection into the tiny set of looping blood vessels in
bloodstream of a ﬂuid that is the nephron where blood is ﬁltered
later measured in a 24-hour urine in the kidney.
collection. A modiﬁed GFR
Goodpasture syndrome: An
calculation requires only that
uncommon disease that usually
the creatinine in a blood sample
includes bleeding from the
be measured. Each laboratory
lungs, coughing up of blood, and
has its own normal range for
inﬂammation of the kidneys that
measurements. Generally, the
can lead to kidney failure. This
normal range for men is 97 to
condition is an autoimmune disease.
137 mL/min/1.73 m2 of body surface
area. The normal range for women
is 88 to 128 mL/min/1.73 m2.
graft: In hemodialysis (see dialysis), a the Escherichia coli bacterium in
vascular access surgically created contaminated food. People with
using a synthetic tube to connect an HUS may develop acute renal
artery to a vein. In transplantation failure.
(see transplant), a graft is the
hormone (HOR-mone): A natural
transplanted organ or tissue.
chemical produced in one part
of the body and released into
Looped the blood to trigger or regulate
Artery 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.
Graft hydronephrosis (HY-droh-nef-ROH
sis): Swelling of the top of the
hematocrit (hee-MAT-uh-krit): A ureter, usually because something
measure that tells what portion of a is blocking the urine from ﬂowing
blood sample consists of red blood into or out of the bladder.
cells. Low hematocrit suggests
anemia or massive blood loss.
ee-uh): Blood in the urine, which
can be a sign of a kidney stone,
glomerulonephritis, or other kidney
hemodialysis: See dialysis. Unhealthy Kidney
hemolytic (HEE-moh-LIT-ik) Kidney smaller
uremic (yoo-REE-mik) syndrome
(SIN-drome) (HUS): A disease Urine dammed back
that affects the blood and blood into renal pelvis
vessels. It destroys red blood
cells, cells that cause the blood Renal stone
stuck in ureter
to clot, and the lining of blood
vessels. HUS is often caused by Hydronephrosis
hypercalciuria (HY-per-kal-see kidney. The IgA protein damages
YOO-ree-uh): Abnormally large the glomeruli, leading to blood
amounts of calcium in the urine. and protein in the urine, to
swelling in the hands and feet, and
sometimes to kidney failure.
ree-uh): Unusually large amounts
of oxalate in the urine, leading to immune (im-YOON) system: The
kidney stones. body’s system for protecting itself
from viruses and bacteria or any
High blood pressure, which can be
caused either by too much ﬂuid in immunosuppressant (im-YOON-oh
the blood vessels or by narrowing suh-PRESS-unt): A drug given
of the blood vessels. to suppress the natural responses
of the body’s immune system.
Amount of Diameter of Blood Immunosuppressants are given
blood blood vessel pressure to transplant patients to prevent
in vessel organ rejection and to patients
Normal High with autoimmune diseases like
Too much ﬂuid interstitial (IN-ter-STISH-ul)
Inﬂammation of the kidney cells
that are not part of the ﬂuid
Normal Narrow High
collecting units, a condition that
can lead to acute renal failure or
chronic kidney disease.
IgA nephropathy (nef-RAHP-uh pyelogram (PY-loh-gram): An
thee): A kidney disorder caused x ray of the urinary tract. A dye
by deposits of the protein is injected to make the kidneys,
immunoglobulin A (IgA) inside ureters, and bladder visible on the
the glomeruli (ﬁlters) within the x ray and show any blockage in
the urinary tract.
kidney (KID-nee): One of the two erythematosus (eh-rih-theh-mah
bean-shaped organs that ﬁlter TOH-sis). The condition can
wastes from the blood. The cause hematuria and proteinuria,
kidneys are located near the and it may progress to end-stage
middle of the back. They create renal disease.
urine, which is delivered to the
membrane (MEM-brane): A thin
bladder through tubes called
sheet or layer of tissue that lines
a cavity or separates two parts of
kidney failure: Loss of kidney the body. A membrane can act
function. (See also end-stage renal as a ﬁlter, allowing some particles
disease, acute renal failure, and to pass from one part of the body
chronic kidney disease.) to another while keeping others
where they are. The membrane
kidney stone: A stone that develops
in a dialyzer ﬁlters waste products
from crystals that form in urine
from the blood.
and build up on the inner surfaces
of the kidney, in the renal pelvis, or
in the ureters.
Kt/V (kay-tee over vee): A
Blood cells Waste
measurement of dialysis dose. Waste products
The measurement takes into products
account the efﬁciency of the
dialyzer, the treatment time, and
the total volume of urea in the
body. See also URR.
lithotripsy (LITH-oh-TRIP-see): A membrane
method of breaking up kidney Dialysis solution
stones using shock waves or other compartment
lupus (LOO-pus) nephritis (nef Dialyzer Membrane
RY-tis): Inﬂammation of the
kidneys caused by an autoimmune
disease called systemic lupus
membranoproliferative (MEM nephrolithiasis (NEF-roh-lih-THY
bray-no-pro-LIF-er-uh-tiv) uh-sis): See kidney stones.
nephrologist (nef-RAHL-oh-jist): A
yoo-loh-nef-RY-tis): A disease
doctor who treats patients with
that occurs primarily in children
kidney problems or hypertension.
and young adults. Over time,
inﬂammation leads to scarring in nephron (NEF-rahn): A tiny part of
the glomeruli, causing proteinuria, the kidneys. Each kidney is made
hematuria, and sometimes chronic up of about 1 million nephrons,
kidney disease or end-stage renal which are the working units of
disease. the kidneys, removing wastes and
extra ﬂuids from the blood.
membranous nephropathy (neh
FROP-uh-thee): A disorder nephropathy (neh-FROP-uh-thee):
that hinders the kidneys’ ability Any disease of the kidney.
to ﬁlter wastes from the blood
because of harmful deposits nephrotic (nef-RAH-tik) syndrome:
on the glomerular membrane. A collection of symptoms
Some cases of membranous that indicate kidney damage.
nephropathy develop after an Symptoms include high levels
autoimmune disease or malignancy, of protein in the urine, lack of
but most develop without a known protein in the blood, and high
cause. blood cholesterol.
nephrectomy (nef-REK-tuh-mee): nuclear (NEW-klee-ur) scan: A
Surgical removal of a kidney. test of the structure, blood ﬂow,
and function of the kidneys. The
nephrogenic (NEF-roh-JEN-ik) doctor injects a mildly radioactive
diabetes (DY-uh-BEE-teez) solution into an arm vein and
insipidus (in-SIP-ih-dus): uses x rays to monitor its progress
Constant thirst and frequent through the kidneys.
urination because the kidney
tubules cannot respond to oxalate (AHK-suh-late): A chemical
antidiuretic hormone. The result is that combines with calcium in
an increase in urine formation and urine to form the most common
excessive urine ﬂow. type of kidney stone (calcium
pelvis (PELL-vis): The bowl-shaped proteinuria (PRO-tee-NOOR-ee-uh):
bone that supports the spine and A condition in which the urine
holds up the digestive, urinary, contains large amounts of protein,
and reproductive organs. The legs a sign that the kidneys are not
connect to the body at the pelvis. functioning properly.
percutaneous (PER-kyoo-TAY pyelonephritis (PY-loh-nef-RY-tis):
nee-us) nephrolithotomy An infection of the kidneys, usually
(NEF-roh-lih-THAH-tuh-mee): caused by a germ that has traveled
A method for removing kidney up through the urethra, bladder,
stones via keyhole surgery through and ureters from outside the body.
renal (REE-nul): Of the kidneys. A
peritoneal dialysis: See dialysis. renal disease is a disease of the
kidneys. Renal failure means the
polycystic (PAHL-ee-SIS-tik) kidney
kidneys have stopped working
disease (PKD): An inherited
disorder characterized by many
grape-like clusters of ﬂuid-ﬁlled renal agenesis (ay-JEN-eh-sis): The
cysts that make both kidneys larger absence or severe malformation
over time. These cysts take over of one or both kidneys.
and destroy working kidney tissue.
renal cell carcinoma (KAR-sih-NOH
PKD may cause chronic kidney
mah): A type of kidney cancer.
disease and end-stage renal disease.
renal cysts (SISTS): Abnormal ﬂuid
ﬁlled sacs in the kidney that range
in size from microscopic to much
larger. Many simple cysts are
Ureter harmless, while other types can
seriously damage the kidneys.
renal osteodystrophy (AH-stee transplant (TRANZ-plant):
oh-DIS-truh-fee): Weak bones Replacement of a diseased organ
caused by poorly working kidneys. with a healthy one. A kidney
Renal osteodystrophy is a transplant may come from a living
common problem for people on donor, usually a relative, or from
dialysis who have high phosphate someone who has just died.
levels or insufﬁcient vitamin D
ultrasound: A technique that
bounces safe, painless sound
renal pelvis (PELL-vis): The basin waves off organs to create an
into which the urine formed by image of their structure.
the kidneys is excreted before it
urea (yoo-REE-uh): A waste
travels to the ureters and bladder.
product found in the blood and
renal tubular (TOOB-yoo-lur) caused by the normal breakdown
acidosis (ASS-ih-DOH-sis): A of protein in the liver. Urea is
defect in the kidneys that hinders normally removed from the blood
their normal excretion of acids. by the kidneys and then excreted
Failure to excrete acids can lead in the urine. Urea accumulates
to weak bones, kidney stones, and in the body of people with kidney
poor growth in children. failure.
renal vein thrombosis (throm-BOH uremia (yoo-REE-mee-uh): The
sis): Blood clots in the vessel illness associated with the buildup
that carries blood away from the of urea in the blood because
kidney. This can occur in people the kidneys are not working
with the nephrotic syndrome. effectively. Symptoms include
nausea, vomiting, loss of appetite,
renin (REE-nin): A hormone made
weakness, and mental confusion.
by the kidneys that helps regulate
the volume of ﬂuid in the body ureteroscope (yoo-REE-tur-uh
and blood pressure. scope): A tool for examining
the bladder and ureters and for
struvite (STROO-vite) stone: A
removing kidney stones through
type of kidney stone caused by
the urethra. The procedure is
called ureteroscopy (yoo-ree-tur
ureters (YOOR-uh-turs): Tubes that urine (YOOR-in): Liquid waste
carry urine from the kidneys to the product ﬁltered from the blood by
bladder. the kidneys, stored in the bladder,
and expelled from the body
urethra (yoo-REE-thrah): The tube
through the urethra by the act of
that carries urine from the bladder
voiding or urinating.
to the outside of the body.
uric (YOOR-ik) acid stone: A kidney
sis): Stones in the urinary tract.
stone that may result from a diet
high in animal protein. When the URR (urea reduction ratio): A blood
body breaks down this protein, uric test that compares the amount
acid levels rise and can form stones. of blood urea nitrogen before
and after dialysis to measure the
urinalysis (yoor-in-AL-ih-sis): A test
effectiveness of the dialysis dose.
of a urine sample that can reveal
many problems of the urinary vasculitis (VAS-kyoo-LY-tis):
tract and other body systems. The Inﬂammation of the blood vessel
sample may be observed for color, walls. This can cause rash and
cloudiness, concentration; signs of disease in multiple organs of the
drug use; chemical composition, body, including the kidneys.
including glucose; the presence of
protein, blood cells, or germs; or
REE-ter-ul) reﬂux: An abnormal
other signs of disease.
condition in which urine backs up
urinary (YOOR-ih-NEHR-ee) tract: into the ureters, and occasionally
The system that takes wastes from into the kidneys, raising the risk of
the blood and carries them out of infection.
the body in the form of urine. The
void: To urinate, empty the bladder.
urinary tract includes the kidneys,
renal pelvises, ureters, bladder, and Wegener’s granulomatosis (GRAN
urethra. yoo-LOH-muh-TOH-sis): An
autoimmune disease that damages
urinary tract infection (UTI): An illness
the blood vessels and causes
caused by harmful bacteria growing
disease in the lungs, upper
in the urinary tract.
respiratory tract, and kidneys.
urinate (YOOR-ih-nate): To release
urine from the bladder to the
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AND HUMAN SERVICES
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NIH Publication No. 03–4359