Gastrointestinal Disorders For The Pathologist

Front 1

What diseases do Helicobacter pylori cause?

Back 1

duodenitis, duodenal ulcers, type B chronic antral gastritis, gastric ulcers, nonulcer dyspepsia, gastric carcinoma, and MALTomas.

Front 2

What is used for the diagnosis of Helicobacter pylori?

Back 2

Tissue sampling, breath tests, and serology are used for diagnosis.

Front 3

What is the underlying principle of the tests used for diagnosing Helicobacter pylori?

Back 3

Testing utilizes the ability of the organism to produce urease (urease splits urea to form ammonia).

Front 4

What stains can be used on tissue to confirm Helicobacter pylori?

Back 4

Warthin-Starry or Giemsa’s stain.

Front 5

What test confirms eradication of H. pylori after treatment?

Back 5

Breath test.

Front 6

What conditions suggest hypersecretory states of gastrin?

Back 6

peptic acid disease in the absence of H. pylori or NSAID use. Failure to respond to H2-receptor blocking agents and PPIs are also suggestive.

Front 7

What is the process of determining gastrin levels?

Back 7

H2-receptor blockers should be held for 48 hours and PPIs for 7 days before testing.
Secretin can be given (2U/kg) with gastrin levels drawn at 2, 5, 10, 15, and 20 minutes.

Front 8

What values give a positive gastrin test result?

Back 8

An increase of more than 100 ng/L (normal <50 ng/L) is a positive result.

Front 9

What laboratory values suggest a gastrinoma?

Back 9

Serum gastrin levels greater than 150 ng/L (normal <100 ng/L) and pH levels <3.

Front 10

What are the characteristics of chronic diarrhea?

Back 10

more than 3 loose stools per day for more than 4 weeks or daily stool weight >200 g/day.

Front 11

What are the types of chronic diarrhea?

Back 11

Inflammatory diarrhea.
Secretory diarrhea.
Osmotic diarrhea.
Motility disorders.

Front 12

What are the features of inflammatory diarrheas?

Back 12

Often bloody with presence of leukocytes.
Examples include Crohn’s disease, ulcerative colitis, radiation colitis, ischemic colitis, and infectious colitis. Atypical inflammatory diarrheas such as collagenous colitis and microscopic colitis do not produce exudate but rather have hypersecretion or decreased absorption.

Front 13

What are the features of secretory diarrheas?

Back 13

Caused by active secretion of water that is greater than absorption capability.
Continues to create diarrhea even with fasting.
Can be caused by gastrinomas, carcinoid syndrome, VIP-producing carcinoma, mastocytosis, villous adenoma, and medullary thyroid carcinoma.

Front 14

What does an osmotic gap <50 mOsm/kg in a patient with chronic diarrhea suggest?

Back 14

that the patient has ingested a laxative causing secretory diarrhea such as sodium phosphate (Fleet phosphosoda).

Front 15

What are the features of osmotic diarrheas?

Back 15

Caused when the osmotic load of the fecal stream favors water loss (osmotic gradient drives water into lumen).
Fasting causes osmotic diarrheas to subside.
Magnesium laxatives (Maalox) can be responsible.

Front 16

What osmotic gap value is associated with osmotic diarrhea?

Back 16

Osmotic gap is characteristically >100 mOsm/kg. Stool MUST be fresh for calculating osmotic gap because fecal bacteria continues to produce osmotic particles.
Osmotic gap: 290- [2 x (Sodium+ Potassium)].

Front 17

What is the formula to determine osmotic gap?

Back 17

Osmotic gap: 290- [2 x (Sodium+ Potassium)].

Front 18

What are the features of a motility disorder resulting in chronic diarrhea?

Back 18

A diagnosis of exclusion.
Short gut syndrome decreases the amount of absorptive gut.
Irritable bowel syndrome can have excessive neural stimulation that decreases stool transit time.

Front 19

What bacteria is seen with nosocomial diarrhea?

Back 19

Clostridium difficile, a Gram-positive, spore-forming anaerobic bacillus.

Front 20

What drugs have been implicated with the development of nosocomial diarrhea?

Back 20

Broad-spectrum antibiotics such as clindamycin, penicillin, and cephalosporins.

Front 21

What are the features of nosocomial diarrhea?

Back 21

Presentation ranges from mild watery diarrhea to pseudomembranous colitis and toxic megacolon.

Front 22

How is nosocomial diarrhea diagnosed?

Back 22

C. difficile toxin A or B virulence factors in stool.
The gold standard is tissue culture cytotoxicity assays that detect cytotoxin B and takes 48 hours to complete.
Rapid enzyme immunoassays take only several hours but are not sensitive or specific.
ELISA is the optimal test in patients with >6 stools per day.
Stool culture takes 96 hours to complete.

Front 23

What causes hepatic malabsorption?

Back 23

obstruction of bile flow, which causes decreased fat absorption and decreased lipase activity.

Front 24

What causes enteric malabsorption?

Back 24

altered bacterial flora (blind loop syndrome, diverticulosis), obstruction of lymph flow, or enteritis.
Enteritis in the ileum results in B12 deficiency and decreased circulating bile acids.

Front 25

What are the hallmarks of malabsorption?

Back 25

Steatorrhea and fat-soluble vitamin deficiencies.

Front 26

What is the definition of steatorrhea?

Back 26

>5g of lipid in feces per 24 hours.

Front 27

What is celiac sprue?

Back 27

Intestinal malabsorption due to sensitivity to the alcohol-soluble portion of gliadin that induces nonspecific villous atrophy of the small intestine.

Front 28

In what patient should celiac sprue be suspected?

Back 28

A patient with iron deficiency anemia, weight loss, diarrhea, and bloating.

Front 29

What conditions are associated with celiac sprue?

Back 29

IgA deficiency, dermatitis herpetiformis, Down syndrome, type I diabetes, and autoimmune thyroid disease.

Front 30

What abnormal cells are found in the peripheral blood of a patient with celiac sprue?

Back 30

Target cells, Howell-Jolly bodies, Heinz bodies, and siderocytes.

Front 31

What tests are used to diagnose celiac sprue?

Back 31

Testing for antibodies to gliadin (AGA-IgA and AGA-IgG), endomysium (EMA-IgA), reticulin (ARA-IgA) and transglutaminase (tTG-IgG).

Front 32

Which antibody has the greatest sensitivity and specificity for celiac sprue?

Back 32

Endomysial antibodies.

Front 33

What is the gold standard for the diagnosis of celaic sprue?

Back 33

Flattened small bowel villi that respond to dietary changes.

Front 34

What clinical sequelae are associated with Whipple disease?

Back 34

Arthralgias, diarrhea, and weight loss.

Front 35

What causes Whipple disease?

Back 35

Tropheryma whippelii, a Gram-positive rod.

Front 36

How is Whipple disease diagnosed?

Back 36

PCR testing for infected tissue and CSF or biopsy of duodenum with PAS staining.

Front 37

What is the treatment for Whipple disease?

Back 37

Long-term antibiotic therapy with CNS penetration.

Front 38

What is the significance of the Clinitest tablet?

Back 38

It can be sued to test for disaccharidase deficiency.
Normal = 0.25 g/dL
Suspicious = 0.25-0.5 g/dL
Abnormal = >.5g/dL

Front 39

What is the significance of perinuclear-antineutrophilic cytoplasmic antibody (pANCA) as it concerns inflammatory bowel disease?

Back 39

It is found in 70% of ulcerative colitis patients and 20% of Crohn’s disease patients but rarely in irritable bowel syndrome.

Front 40

What is the significance of anti-saccharomyces cerevisae (ASCA) as it concerns inflammatory bowel disease?

Back 40

It is found in 65% of patients with Crohn’s disease and 20% of ulcerative colitis patients but rarely in irritable bowel syndrome.

Front 41

What clinical sequelae are associated with carcinoid?

Back 41

Abdominal pain, flushing, diarrhea, asthma, edema

Front 42

What protein is elevated in carcinoid?

Back 42

Serotonin.

Front 43

What clinical sequelae are associated with gastrinoma?

Back 43

Ulcers, diarrhea

Front 44

What is gastrin?

Back 44

A gastrointestinal hormone produced by antral G cells that regulates gastric acid secretion, stimulates gastric mucosa growth, increases blood flow to the stomach, and increases gastric and intestinal motility.
Originates from preprogastrin that is cleaved by trypsin to form gastrin.

Front 45

What are the features of gastrin?

Back 45

Optimal pH is 5-7, and a low pH has a negative-feedback mechanism.
Three forms: G34 (big gastrin), G17 (little gastrin), and G14 (mini gastrin).

Front 46

What is the significance of measuring gastrin levels?

Back 46

Used to diagnose suspected gastrin-secreting tumors (gastrinomas, Zollinger-Ellison syndrome).

Front 47

How are gastrin levels measured?

Back 47

Determined by RIA or ELISA.
Patient must fast 12 hours before testing because G34 doubles and G17 quadruples following a meal.
Specimen must be frozen immediately because gastrin is unstable in serum. 50% of its immunoreactivity is lost within 48 hours at 4ºC. Should be measured immediately after thawing.

Front 48

What is the normal reference range of gastrin?

Back 48

<100 ng/L, but gastrin increases with age.

Front 49

In what conditions can elevated gastrin be seen?

Back 49

gastric ulcer disease, hyperparathyroidism, chronic renal failure, short bowel syndrome, pernicious anemia, and vagotomy.

Front 50

Why is gastrin measured during the removal of a gstrin-secreting tumor?

Back 50

. If the entire specimen is removed, levels drop to within reference values within 20 minutes.

Front 51

What gastrin level suggests the presence of a gastrinoma?

Back 51

Gastrin > 1000 ng/L.

Front 52

What gastrin level suggests Zollinger-Ellison syndrome.

Back 52

Gastrin levels 2000 x normal.

Front 53

What is pepsin?

Back 53

An enzyme that hydrolyzes proteins to polypeptides.

Front 54

What are the features of pepsin and pepsinogen?

Back 54

Pepsinogen is activated by gastric acid to pepsin.
Pepsinogen I (PGI, pepsinogen A) and pepsinogen II (PGII, pepsinogen C) are stimulated by the vagus nerve, gastrin, secretin, and CCK and inhibited by gastric inhibitory peptide (GIP), vagotomy, H2-receptor antagonists, and anticholinergics.

Front 55

At what pH are pepsinogens activated?

Back 55

A low (acidic) pH.

Front 56

At what pH are pepsinogens destroyed?

Back 56

A high (alkaline) pH.

Front 57

What is the ratio of PGI to PGII?

Back 57

4:1.

Front 58

With what conditions is elevated pepsinogen associated?

Back 58

Diseases that cause increased gastric output such as gastrinomas, Zollinger-Ellison syndrome, gastritis, and duodenal ulcer disease.

Front 59

Wit what conditions is decreased pepsinogen associated?

Back 59

Atrophic gastritis and gastric carcinoma.

Front 60

What is an Apt test?

Back 60

It is a test used to determine if the blood in the GI tract of a newborn is from the infant or the mother.

Front 61

How is the Apt test performed?

Back 61

Stool sample is mixed with water, centrifuged, and the pink supernatant is mixed with 1% sodium hydroxide in a 5:1 ratio.
Turns yellow-brown if of maternal origin and remains pink if of fetal origin. Results occur due to HbF being more resistant to alkali denaturation.

Front 62

What is the significance of measuring carotenoids in stool?

Back 62

Carotenoids are the major precursor for vitamin A, a fat-soluble vitamin (depends upon presence of fat for absorption).

Front 63

What conditions can cause low serum carotenoid?

Back 63

Steatorrhea, liver disease, and high fever.

Front 64

What conditions can cause elevated serum carotenoids?

Back 64

Hypothyroidism, diabetes, hyperlipidemia, and excessive intake of carotene.

Front 65

What is the significance of the breath test concerning the diagnosis of steatorrhea?

Back 65

Based on measurement of 14CO2 in expired air following labeled triglycerides (triolein, tripalmitin, and trioctanoin).
Steatorrhea results in a decreased expired CO2, corresponding to decreased absorption of triglycerides.

Front 66

How is a pancreatic cause of steatorrhea distinguished from other causes of steatorrhea using the breath test?

Back 66

A two-stage test is used in which the patient is given labeled triglycerides in the first stage and the patient is given labeled triglycerides and pancreatic enzymes in the second stage.

Front 67

What tests are used to diagnose steatorrhea?

Back 67

Carotenoids, breath test, fecal fat, titrimetric method

Front 68

How is fecal fat determination performed?

Back 68

Patient must be placed on 100 g fat diet in adults.
In children, fecal fat determination is based upon percent coefficient of fat retention.
Coefficient of fat retention = [(Dietary fat-Fecal fat)]/Dietary fat) x 100.
<95% is indicative of steatorrhea.

Front 69

What test is used for the definitive diagnosis of steatorrhea?

Back 69

Fecal fat determination.

Front 70

What are the limitations of fecal fat determination?

Back 70

Measurement from wet weight concentration is the least informative, measurement from dry weight concentration is slightly more informative, and measurement from 24 hours is the most informative.

Front 71

How is the titrimetric method of fat determination performed?

Back 71

Fats and fatty acids are converted to soap through boiling of the feces with addition of alcoholic potassium hydroxide.
After cooling, hydrochloric acid is added to convert the soaps to fatty acids, which are then extracted with petroleum ether.
Calculated as fatty acids titrated with sodium hydroxide.

Front 72

What is the D-xylose test?

Back 72

A test for malabsorption.

Front 73

How is a D-xylose test perrformed?

Back 73

Patient is given a 25g dose of pentose sugar in 250g water administered orally, and the amount excreted in urine over 5 hours is measured.
<3g excreted is enterogenous malabsorption because pancreatic enzymes are not required for absorption of D-xylose.
Rate of absorption also depends on rate of excretion so a blood sample should be collected in patients with renal insufficiency 2 hours after administration of xylose.

Front 74

What does clay colored stool suggest?

Back 74

Absence of bile or presence of barium sulfate.

Front 75

What are the characteristics of stool from a patient with steatorrhea?

Back 75

Large amounts of soft, foul-smelling, gray stool.

Front 76

What causes black stool?

Back 76

Bismuth, iron, charcoal, and upper GI bleed.

Front 77

What causes green stool?

Back 77

Spinach, calomel, biliverdin, oral antibiotics.

Front 78

What does translucent mucus in stool suggest?

Back 78

spastic constipation or mucous colitis.

Front 79

What does bloody mucus in stool suggest?

Back 79

Neoplasm or inflammatory process.

Front 80

What does mucus with pus in stool suggest?

Back 80

Inflammatory process.

Front 81

How is fat in stool visualized microscopically?

Back 81

Sudan or Oil Red O stain by placing a small amount of stool on a slide and adding two drops of 95% ethanol, then two drops of saturated ethanolic solution of Sudan III.
Neutral fats appear as large orange-red droplets whereas fatty acids can appear as lightly stained flakes or unstained needle-like crystals.
If results are unequivocal, repeat the procedure adding several drops of 36% acetic acid and warming the mixture until it starts to boil.
This process converts fats and soaps to fatty acids.
Up to 100 stained droplets per HPF is normal.

Front 82

How are meat fibers visualized microscopically in stool?

Back 82

Stool is mixed with 10% alcohol solution of eosin for 3 minutes, and only rectangular fibers with cross-striation are counted.

Front 83

How are leukocytes visualized microscopically in stool?

Back 83

Mucus or a drop of liquid stool is placed on a slide and Loffler methylene blue is added. A differential count of at least 200 cells is made.

Front 84

Why is fecal occult blood testing performed?

Back 84

Decreases mortality from colon cancer by 15-35%.

Front 85

What are the features of the Guiac fecal occult blood test?

Back 85

Guiac is a phenolic compound that oxidizes quinone by hydrogen peroxide causing a color change.
Can detect presence of >20 mL/day blood in stool.
Need 3 consecutive stool samples.
Drugs that cause GI irritation (anticoagulants, aspirin, NSAIDs, colchicines, iron) can cause false-positives.
Ingestion of large amounts of vitamin C can cause a false-negative.

Front 86

What are the features of the HemeSelect fecal occult blood test?

Back 86

HemeSelect is an antigen-antibody reaction that does not react with nonhuman hemoglobin or peroxidase, unlike guiac. Also more specific for lower GI bleed because it targets the portion of hemoglobin that does not survive passage in the upper GI tract.

Front 87

How is a lactose tolerance test performed?

Back 87

The patient has to fast overnight and receives 50 g of lactose in 400 mL of water.
Blood is drawn at 30, 60, and 120 minutes after ingestion for testing. An optional 5-hour stool sample can be collected.

Front 88

What lactose tolerance test value is associated with lactose tolerance?

Back 88

Patients with deficiency have a rise <20mg/dL in glucose.

Front 89

How much lactose is given to a child when performing a lactose tolerance test?

Back 89

The dose of lactose in children is 2g/kg.