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An enzyme in the small intestine needed to digest milk sugar (lactose).

Lactase Deficiency
(LAK-tayss duh-FISH-en-see)

Lack of the lactase enzyme. Causes lactose intolerance.


The sugar found in milk. The body breaks lactose down into galactose
and glucose.

Lactose Intolerance
(LAK-tohss in-TAH-luh-runs)

Being unable to digest lactose, the sugar in milk. This condition occurs
because the body does not produce the lactase enzyme.

Lactose Tolerance Test
(LAK-tohss TAH-luh-runs test)

A test for lactase deficiency. The patient drinks a liquid that contains
milk sugar. Then the patient’s blood is tested; the test measures the
amount of milk sugar in the blood.


A thin tube with a tiny video camera attached. Used to look inside the
body and see the surface of organs. See also Endoscope.

Laparoscopic Cholecystectomy
Laparoscopic Cholecystectomy
(LAP-uh-ruh-SKAWP-ik KOH-luh-sis-TEK-tuh-mee)

An operation to remove the gallbladder. The doctor inserts a laparoscope
(see above) and other surgical instruments through small holes in the
abdomen. The camera allows the doctor to see the gallbladder on a television
screen. The doctor removes the gallbladder through the holes.

(LAP-uh RAW-skuh-pee)

A test that uses a laparoscope to look at and take tissue from the inside
of the body.


An operation that opens up the abdomen.

Large Intestine
(LARJ in-TES-tin)

The part of the intestine that goes from the cecum to the rectum. The
large intestine absorbs water from stool and changes it from a liquid
to a solid form. The large intestine is 5 feet long and includes the appendix,
cecum, colon, and rectum. Also called colon.


A cleaning of the stomach and colon. Uses a special drink and enemas.
See also Bowel Prep.


Medicines to relieve long-term constipation. Used only if other methods
fail. Also called cathartics.

Lazy Colon
(LAY-zee KOH-lun)

See Atonic Colon.

Levator Syndrome
(luh-VAY-tur sin-drohm)

Feeling of fullness in the anus and rectum with occasional pain. Caused
by muscle spasms.

Lithotripsy, Extracorporeal Shock Wave (ESWL)
(LITH-uh-trip-see, EK-struh-cor-POH-ree-ul SHAHK wayv)

A method of breaking up bile stones and gallstones. Uses a specialized
tool and shock waves.


The largest organ in the body. The liver carries out many important
functions, such as making bile, changing food into energy, and cleaning
alcohol and poisons from the blood.

Liver Enzyme Tests
(LIH-vur EN-zym tests)

Blood tests that look at how well the liver and biliary system are working.
Also called liver function tests.

Liver Function Tests
(LIH-vur FUNK-shun tests)

See Liver Enzyme Tests.

Lower Esophageal Ring
(LOH-wur uh-saw-fuh-JEE-ul Ring)

An abnormal ring of tissue that may partially block the lower esophagus.
Also called Schatzki’s ring.

Lower Esophageal Sphincter
Lower Esophageal Sphincter
(LOH-wur uh-saw-fuh-JEE-ul SFEENK-tur)

The muscle between the esophagus and stomach. When a person swallows,
this muscle relaxes to let food pass from the esophagus to the stomach.
It stays closed at other times to keep stomach contents from flowing back
into the esophagus.

Lower GI Series
(LOH-wur jee-eye SEER-eez)

X-rays of the rectum, colon, and lower part of the small intestine.
A barium enema is given first. Barium coats the organs so they will show
up on the x-ray. Also called barium enema x-ray.


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Magnetic Resonance Imaging (MRI)
Magnetic Resonance Imaging (MRI)
(mag-NEH-tik REH-zuh-nuns IM-uh-jing)

A test that takes pictures of the soft tissues in the body. The pictures
are clearer than x-rays.

Malabsorption Syndromes
(MAL-ub-SORP-shun sin-drohmz)

Conditions that happen when the small intestine cannot absorb nutrients
from foods.

Mallory-Weiss Tear
(MAH-luh-ree-WYSS tair)

A tear in the lower end of the esophagus. Caused by severe vomiting.
Common in alcoholics.


A condition caused by not eating enough food or not eating a balanced


Tests that measure muscle pressure and movements in the GI tract. See
also Esophageal Manometry and Rectal Manometry.

Meckel’s Diverticulum
(MEH-kulz dy-vur-TIK-yoo-lum)

A birth defect in which a small sac forms in the ileum.


A huge, swollen colon. Results from severe constipation. In children,
megacolon is more common in boys than girls. See also Hirschsprung’s Disease.


Blood in the stool.

Ménétrier’s Disease
(may-NAY-tree-ayz duh-zeez)

A long-term disorder that causes large, coiled folds in the stomach.
Also called giant hypertrophic gastritis.


The way cells change food into energy after food is digested and absorbed
into the blood.


The movement of food through the digestive tract.

Motility Disorders
(moh-TIL-uh-tee dis-or-durz)

See Functional Disorders.

Mucosal Protective Drugs
(myoo-KOH-zul proh-TEK-tiv drugz)

Medicines that protect the stomach lining from acid. Examples are sucralfate
(soo-CRAL-fayt) (Carafate), misoprostol (MIH-soh-PROH-stawl)
(Cytotec), antacids (Mylanta and Maalox), and bismuth subsalicylate (Pepto-Bismol).

Mucous Colitis
(MYOO-kus koh-LY-tis)

See Irritable Bowel Syndrome.

Mucosal Lining
(myoo-KOH-zul LY-ning)

The lining of GI tract organs that makes mucus.


A clear liquid made by the intestines. Mucus coats and protects tissues
in the GI tract.


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The feeling of wanting to throw up (vomit).


Dead tissue that surrounds healthy tissue in the body.

Necrotizing Enterocolitis
(NEK-roh-TY-zing EN-tuh-roh-koh-LY-tis)

A condition in which part of the tissue in the intestines is destroyed.
Occurs mainly in under-weight newborn babies. A temporary ileostomy may
be necessary.

Neonatal Hepatitis
(nee-oh-NAY-tul heh-puh-TY-tis)

Irritation of the liver with no known cause. Occurs in newborn babies.
Symptoms include jaundice and liver cell changes.


New and abnormal growth of tissue that may or may not cause cancer.
Also called tumor.

Nissen Fundoplication
Nissen Fundoplication
(NIH-sun FUN-doh-plih-KAY-shun)

An operation to sew the top of the stomach (fundus) around the esophagus.
Used to stop stomach contents from flowing back into the esophagus (reflux)
and to repair a hiatal hernia.

Nontropical Sprue

See Celiac Disease.

Nonulcer Dyspepsia
(nawn-UL-sur dis-PEP-see-uh)

Constant pain or discomfort in the upper GI tract. Symptoms include
burning, nausea, and bloating, but no ulcer. Possibly caused by muscle

Norwalk Virus
(NAWR-wawk VY-rus)

A virus that may cause GI infection and diarrhea. See also Gastroenteritis.

Nutcracker Syndrome
(NUT-KRAK-ur sin-drohm)

Abnormal muscle tightening in the esophagus.


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A blockage in the GI tract that prevents the flow of liquids or solids.

Occult Bleeding

Blood in stool that is not visible to the naked eye. May be a sign of
disease such as diverticulosis or colorectal cancer.

Oral Dissolution Therapy
(OR-ul dih-soh-LOO-shun theh-ruh-pee)

A method of dissolving cholesterol gallstones. The patient takes the
oral medications chenodiol (KEE-noh-DY-awl) (Chenix) and
ursodiol (ERS-oh-DY-awl) (Actigall). These medicines are
most often used for people who cannot have an operation.


A person who has an ostomy. Called ostomist in some countries.


An operation that makes it possible for stool to leave the body through
an opening made in the abdomen. An ostomy is necessary when part or all
of the intestines are removed. Colostomy and ileostomy are types of ostomy.


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A gland that makes enzymes for digestion and the hormone insulin.


Irritation of the pancreas that can make it stop working. Most often
caused by gallstones or alcohol abuse.

Papillary Stenosis
(PAH-pih-lair-ee stuh-NOH-sis)

A condition in which the openings of the bile ducts and pancreatic ducts

Parenteral Nutrition
(puh-REN-tuh-rul noo-TRISH-un)

A way to provide a liquid food mixture through a special tube in the
chest. Also called hyperalimentation or total parenteral nutrition.

Parietal Cells
(puh-RY-uh-tul selz)

Cells in the stomach wall that make hydrochloric acid.

Pediatric Gastroenterologist
(pee-dee-AT-trik GAH-stroh-en-tuh-RAW-luh-jist)

A doctor who treats children with digestive diseases.


An enzyme made in the stomach that breaks down proteins.

Peptic Ulcer

Related to the stomach and the duodenum, where pepsin is present.

Peptic Ulcer
(PEP-tik UL-sur)

A sore in the lining of the esophagus, stomach, or duodenum. Usually
caused by the bacterium Helicobacter pylori. An ulcer in the stomach
is a gastric ulcer; an ulcer in the duodenum is a duodenal ulcer.


Passing through the skin.

Percutaneous Transhepatic Cholangiography
(PUR-kyoo-TAY-nee-us tranz-heh-PAT-ik koh-LAN-jee-AW-gruh-fee)

X-rays of the gallbladder and bile ducts. A dye is injected through
the abdomen to make the organs show up on the x-ray.

Perforated Ulcer
(PUR-fuh-ray-ted UL-sur)

An ulcer that breaks through the wall of the stomach or the duodenum.
Causes stomach contents to leak into the abdominal cavity.


A hole in the wall of an organ.


The area around the anus.


Related to the perineum.


The area between the anus and the sex organs.


A wavelike movement of muscles in the GI tract. Peristalsis moves food
and liquid through the GI tract.


The lining of the abdominal cavity.


Infection of the peritoneum.

Pernicious Anemia
(pur-NIH-shus uh-NEE-mee-uh)

Anemia caused by a lack of vitamin B12. The body needs B12
to make red blood cells.

Peutz-Jeghers Syndrome
(POYTS-YAY-gurz sin-drohm)

An inherited condition. Many polyps grow in the intestine. There is
little risk of cancer.


The space behind the mouth. Serves as a passage for food from the mouth
to the esophagus and for air from the nose and mouth to the larynx.


Tissue bulging from the surface of an organ. Although these growths
are not normal, they often are not cause for concern. However, people
who have polyps in the colon may have an increased risk of colorectal


The presence of many polyps.


A group of rare, inherited blood disorders. When a person has porphyria,
cells fail to change chemicals (porphyrins) to the substance (heme) that
gives blood its color. Porphyrins then build up in the body. They show
up in large amounts in stool and urine, causing the urine to be colored
blue. They cause a number of problems, including strange behavior.

Portal Hypertension
(POR-tul hy-pur-TEN-shun)

High blood pressure in the portal vein. This vein carries blood into
the liver. Portal hypertension is caused by a blood clot. This is a common
complication of cirrhosis.

Portal Vein
(POR-tul vayn)

The large vein that carries blood from the intestines and spleen to
the liver.

Portosystemic Shunt
(POR-toh-sih-STEM-ik shunt)

An operation to create an opening between the portal vein and other
veins around the liver.

Postcholecystectomy Syndrome
(POST-koh-luh-sis-TEK-tuh-mee sin-drohm)

A condition that occurs after gallbladder removal. The muscle between
the gallbladder and the small intestine does not work properly, causing
pain, nausea, and indigestion. Also called biliary dyskinesia.

Postgastrectomy Syndrome
(POST-gah-STREK-tuh-mee sin-drohm)

A condition that occurs after an operation to remove the stomach (gastrectomy).
See also Dumping Syndrome.

Postvagotomy Stasis
(POST-vay-GAW-tuh-mee STAY-sis)

Delayed stomach emptying. Occurs after surgery on the vagus nerve.


A special bag worn over a stoma to collect stool. Also called an ostomy

Primary Biliary Cirrhosis
(PRY-muh-ree BILL-ee-air-ee suh-ROH-sis)

A chronic liver disease. Slowly destroys the bile ducts in the liver.
This prevents release of bile. Long-term irritation of the liver may cause
scarring and cirrhosis in later stages of the disease.

Primary Sclerosing Cholangitis
(PRY-muh-ree skluh-ROH-sing KOH-lun-JY-tis)

Irritation, scarring, and narrowing of the bile ducts inside and outside
the liver. Bile builds up in the liver and may damage its cells. Many
people with this condition also have ulcerative colitis.

Proctalgia Fugax
(prahk-TAL-jee-uh FYOO-gaks)

Intense pain in the rectum that occasionally happens at night. Caused
by muscle spasms around the anus.


An operation to remove the rectum.


Irritation of the rectum.


An operation to remove the colon and rectum. Also called coloproctectomy.


Irritation of the colon and rectum.


A doctor who specializes in disorders of the anus and rectum.


A short, rigid metal tube used to look into the rectum and anus.


Looking into the rectum and anus with a proctoscope.


Irritation of the rectum and the sigmoid colon.


An endoscopic examination of the rectum and sigmoid colon. See also

Prokinetic Drugs
(PROH-kih-NET-ik drugz)

Medicines that cause muscles in the GI tract to move food. An example
is cisapride (SIS-uh-pryd) (Propulsid).


A condition that occurs when a body part slips from its normal position.


One of the three main classes of food. Protein is found in meat, eggs,
and beans. The stomach and small intestine break down proteins into amino
acids. The blood absorbs amino acids and uses them to build and mend cells.
See also Amino Acids.

Proton Pump Inhibitors
(PROH-tawn pump in-HIH-bih-turz)

Medicines that stop the stomach’s acid pump. Examples are omeprazole
(oh-MEH-prah-zol) (Prilosec) and lansoprazole (lan-SOH-prah-zol)

Prune Belly Syndrome
(PROON bel-ee sin-drohm)

A condition of newborn babies. The baby has no abdominal muscles, so
the stomach looks like a shriveled prune. Also prednisone called Eagle-Barrett syndrome.

Pruritus Ani
(proo-RY-tus AY-ny)

Itching around the anus.

Pseudomembranous Colitis
(SOO-doh-MEM-bray-nus koh-LY-tis)

Severe irritation of the colon. Caused by Clostridium difficile
bacteria. Occurs after taking oral antibiotics, which kill bacteria that
normally live in the colon.

Pyloric Sphincter
(py-LOR-ik SFEENK-tur)

The muscle between the stomach and the small intestine.

Pyloric Stenosis
(py-LOR-ik stuh-NOH-sis)

A narrowing of the opening between the stomach and the small intestine.


An operation to widen the opening between the stomach and the small
intestine. This allows stomach contents to pass prednisone more freely from the stomach.


The opening from the prednisone stomach into the top of the small intestine (duodenum).

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