p.6
Altered Motility in Digestive Disorders
What conditions can lead to altered motility?
Gastrectomy, gastric bypass surgery, post-vagotomy status, Zollinger-Ellison syndrome, duodenal ulcer disease, and diabetes mellitus.
p.28
Laboratory Tests for Diarrhea Differentiation
What does a blue color indicate in the occult blood test?
Gastrointestinal bleeding.
p.29
Chemical Testing of Feces
What does the addition of a Clinitest tablet to emulsified stool detect?
The presence of reducing substances.
p.24
Fecal Fat Testing Methods
What is the Van de Kramer method used for?
Fecal fat extraction and titration of long chain fatty acids by sodium hydroxide.
p.26
Fecal Enzymes and Carbohydrate Testing
What method is used for Chymotrypsin testing?
Spectrophotometric methods.
p.19
Chemical Testing of Feces
What are the dietary or drug restrictions for Hemoccult ICT™?
There are no dietary or drug restrictions.
p.10
Macroscopic and Microscopic Stool Examination
What can cause bulky or frothy stool?
Bile duct obstruction, pancreatic disorders.
p.17
Specimen Collection Techniques
How soon should FOBT samples be tested after collection?
Within 6 days of collection.
p.13
Laboratory Tests for Diarrhea Differentiation
What conditions can be diagnosed or monitored using muscle fiber microscopy?
Pancreatic insufficiency, biliary obstruction, and gastrocolic fistulas.
p.13
Macroscopic and Microscopic Stool Examination
What should be counted during the examination of the stool sample?
The number of undigested fibers.
p.2
Physiology of Stool Formation
How does the fecal electrolyte composition compare to plasma?
Fecal electrolyte is similar to plasma.
p.21
Fecal Fat Testing Methods
What is the Acid Steatocrit used for?
To estimate fat excretion.
p.15
Chemical Testing of Feces
What is the Apt Test used for?
To differentiate between fetal and maternal blood in stool.
p.21
Fecal Fat Testing Methods
What is a notable feature of the NIRA procedure?
No reagents are needed after homogenization.
p.22
Fecal Fat Testing Methods
What is the initial step in the Acid Steatocrit Procedure?
Dilute 0.5g of feces from spot collection 1:4 with deionized water.
p.6
Altered Motility in Digestive Disorders
What are the two types of altered motility mentioned?
Hypermotility and slow motility (IBS).
p.26
Fecal Enzymes and Carbohydrate Testing
What is the historical method used to test for Trypsin in fecal samples?
X-ray paper to emulsify stool.
p.8
Specimen Collection Techniques
What type of container should be used for specimen collection?
A clean disposable container.
p.11
Macroscopic and Microscopic Stool Examination
What is the significance of finding parasites in a stool sample?
It indicates a parasitic infection in the gastrointestinal tract.
p.1
Macroscopic and Microscopic Stool Examination
What does macroscopic stool examination involve?
Visual inspection of stool for color, consistency, and presence of blood or mucus.
p.9
Macroscopic and Microscopic Stool Examination
What are some characteristic appearances of stool?
Bulky, frothy, and mucus-coated.
p.7
Steatorrhea and Its Causes
What role do bile salts play in digestion related to steatorrhea?
Absence of bile salts can contribute to malabsorption and steatorrhea.
p.28
Laboratory Tests for Diarrhea Differentiation
What does a positive result for neutrophils indicate?
A condition affecting the intestinal wall.
p.10
Macroscopic and Microscopic Stool Examination
What are possible causes for black stool?
Iron therapy, charcoal, bismuth (antacids).
p.26
Fecal Enzymes and Carbohydrate Testing
What indicates a positive test for Trypsin?
It digests gelatin on paper, leaving a clear area.
p.29
Fecal Enzymes and Carbohydrate Testing
What is the purpose of placing an emulsified specimen on X-ray paper?
To determine the ability to digest gelatin.
p.3
Diarrhea Classification and Mechanisms
What factors are considered in the severity classification of diarrhea?
The severity of symptoms and impact on health.
p.12
Laboratory Tests for Diarrhea Differentiation
What indicates a positive result in fecal leukocytes microscopy?
More than 3 neutrophils (+).
p.20
Fecal Fat Testing Methods
How is the coefficient of fecal fat calculated?
(Dietary fat – Fecal fat) x 100% / Dietary fat.
p.7
Steatorrhea and Its Causes
What is steatorrhea?
An increase in stool fat exceeding 6 g per day.
p.16
Chemical Testing of Feces
What is the product formed when Hg + H2O2 reacts in FOBT?
Oxidized guaiac (blue) and water.
p.23
Fecal Fat Testing Methods
How is Acid Steatocrit calculated?
Fatty layer length in cm divided by the sum of fatty layer length and solid layer length in cm, multiplied by 100.
p.23
Fecal Fat Testing Methods
What is the formula for calculating fecal fat in grams per 24 hours for adults?
[0.45 x (acid steatocrit in percent as a whole number)] - 0.43, then multiplied by 100.
p.4
Laboratory Tests for Diarrhea Differentiation
What is the formula for calculating the fecal osmotic gap?
Osmotic gap = 290 – [2 (fecal Na + fecal K)].
p.4
Laboratory Tests for Diarrhea Differentiation
What is the typical value of fecal osmolality in relation to serum osmolality?
Close to serum osmolality (290 mOsm/kg).
p.27
Laboratory Tests for Diarrhea Differentiation
What can the copper reduction test distinguish between?
Abnormal excretion of reducing sugars and diarrhea from viruses and parasites.
p.15
Chemical Testing of Feces
What is the significance of detecting occult blood in stool?
It is used for mass screening for early detection of colorectal cancer.
p.15
Chemical Testing of Feces
What types of substances can be tested in feces?
Fecal enzymes and carbohydrates.
p.14
Fecal Fat Testing Methods
What is the purpose of qualitative fecal fats microscopy?
To monitor malabsorption.
p.27
Laboratory Tests for Diarrhea Differentiation
What is the purpose of the copper reduction test?
To test for carbohydrate intolerance.
p.27
Laboratory Tests for Diarrhea Differentiation
What is the procedure for the copper reduction test?
Clinitest tablet™ + 1 part stool : 2 parts water.
p.22
Fecal Fat Testing Methods
What is the next step after adding perchloric acid and vortexing for 30 seconds?
Place the acid-homogenate mixture in a 75 µL plain hematocrit capillary tube and seal it with wax.
p.16
Chemical Testing of Feces
What is the principle of FOBT?
The reaction involves Hg + H2O2 acting as a pseudoperoxidase to produce oxidized guaiac (blue) and water.
p.1
Macroscopic and Microscopic Stool Examination
What are the two main types of stool examination?
Macroscopic examination and microscopic examination.
p.28
Laboratory Tests for Diarrhea Differentiation
What is the methodology for examining neutrophils in fecal screening tests?
Microscopic count of neutrophils stained with methylene blue, Gram stain, or Wright’s stain.
p.28
Fecal Fat Testing Methods
How is qualitative fecal fat examined?
Microscopic examination of a direct smear stained with Sudan III.
p.28
Fecal Fat Testing Methods
What indicates a significant presence of fecal fats?
60 large orange-red droplets in the smear.
p.10
Macroscopic and Microscopic Stool Examination
What can cause red stool aside from bleeding?
Beets and food color, rifampin.
p.19
Chemical Testing of Feces
What type of antibodies does Hemoccult ICT™ use?
Anti-human hemoglobin antibodies.
p.5
Diarrhea Classification and Mechanisms
What are some causes of secretory diarrhea?
Bacterial, viral, protozoan infections, drugs, laxatives, hormones, inflammatory bowel disease, endocrine disorders, neoplasms, collagen vascular disease.
p.13
Laboratory Tests for Diarrhea Differentiation
What indicates a positive result in muscle fiber microscopy?
>10 undigested red-stained fibers with well-preserved striations.
p.1
Macroscopic and Microscopic Stool Examination
What is the primary purpose of stool examination?
To diagnose gastrointestinal disorders and infections.
p.4
Laboratory Tests for Diarrhea Differentiation
How are fecal electrolytes used in diarrhea differentiation?
Na and K are used to calculate the fecal osmotic gap.
p.14
Fecal Fat Testing Methods
What components are measured in qualitative fecal fats microscopy?
Neutral fats (triglycerides), fatty acid salts (soaps), fatty acids, and cholesterol.
p.14
Fecal Fat Testing Methods
What indicates steatorrhea in qualitative fecal fats microscopy?
> 60 large orange-red droplets per high power field (HPO).
p.12
Specimen Collection Techniques
What is the first step in the fecal leukocytes microscopy procedure?
Place mucus or a drop of liquid stool on a slide.
p.5
Diarrhea Classification and Mechanisms
What are some causes of osmotic diarrhea?
Maldigestion or malabsorption like disaccharidase deficiency, celiac sprue, laxatives, antacids, amebiasis, and antibiotic administration.
p.11
Macroscopic and Microscopic Stool Examination
What do muscle fibers in stool samples suggest?
They suggest malabsorption or improper digestion of proteins.
p.7
Steatorrhea and Its Causes
What are some causes of steatorrhea?
Pancreatic insufficiency, absence of bile salts, pancreatic and small bowel disorders causing malabsorption.
p.25
Laboratory Tests for Diarrhea Differentiation
What are the types of maternal hemoglobins distinguished in the Apt Test?
Hemoglobins A, AS, CS, and SS.
p.3
Diarrhea Classification and Mechanisms
What are the four factors used to classify diarrhea?
Duration, mechanism, severity, and characteristic.
p.22
Fecal Fat Testing Methods
What volume of 5 N perchloric acid is added to the homogenate?
An amount equal to 20% of the homogenate volume.
p.23
Fecal Fat Testing Methods
How does the indication of steatorrhea differ between adults and infants?
It is higher in infants and drops with age.
p.17
Specimen Collection Techniques
How many samples from different stools should be tested before confirming a negative result?
2 samples from 3 different stools.
p.11
Fecal Fat Testing Methods
What does qualitative fecal fats testing assess?
It assesses the presence of fat in the stool, indicating malabsorption.
p.1
Macroscopic and Microscopic Stool Examination
What is assessed during microscopic stool examination?
The presence of pathogens, parasites, and abnormal cells.
p.28
Fecal Fat Testing Methods
What is the result of heating a smear with acetic acid and Sudan III?
100 orange-red droplets measuring 6-75 um.
p.19
Chemical Testing of Feces
What does Hemoccult ICT™ specifically test for?
The globin portion of human hemoglobin.
p.5
Diarrhea Classification and Mechanisms
How are electrolytes affected in osmotic diarrhea?
Electrolytes are negligible.
p.12
Macroscopic and Microscopic Stool Examination
What are the two methods of staining used in fecal leukocytes microscopy?
Wet – methylene blue; Dried – Wright’s / Gram methylene blue.
p.9
Macroscopic and Microscopic Stool Examination
What are the different consistencies of stool that can be observed?
Watery, formed, and hard.
p.15
Chemical Testing of Feces
What is the threshold for occult blood to be considered positive?
>2.5 ml of blood per 150 g of stool.
p.19
Chemical Testing of Feces
What is the Hemoquant™ test used for?
It is a flurometric test for hemoglobin and porphyrin.
p.14
Fecal Fat Testing Methods
What is the first step in the procedure for qualitative fecal fats microscopy?
Homogenize one part stool with two parts water.
p.3
Diarrhea Classification and Mechanisms
What are the mechanisms of diarrhea classification?
Secretory, osmotic, and altered motility.
p.22
Fecal Fat Testing Methods
At what speed and duration should the mixture be centrifuged?
Centrifuge horizontally at 13,000 rpm for 15 minutes.
p.29
Chemical Testing of Feces
What does a reaction of 0.5 g/dL reducing substances suggest?
Carbohydrate intolerance.
p.19
Chemical Testing of Feces
What is a key advantage of Hemoccult ICT™?
It is more sensitive to lower GI bleeding.
p.11
Macroscopic and Microscopic Stool Examination
What are fecal leukocytes indicative of in a microscopic examination?
They can indicate inflammation or infection in the gastrointestinal tract.
p.7
Steatorrhea and Its Causes
How does malabsorption relate to steatorrhea?
Malabsorption can lead to increased fat in the stool, resulting in steatorrhea.
p.4
Laboratory Tests for Diarrhea Differentiation
What laboratory tests are used to differentiate mechanisms of diarrhea?
Fecal electrolytes, fecal osmolality, and stool pH.
p.1
Macroscopic and Microscopic Stool Examination
Why is stool examination important in diagnosing infections?
It helps identify the causative agents of gastrointestinal infections.
p.29
Chemical Testing of Feces
What does the addition of sodium hydroxide to a Hg-containing emulsion determine?
The presence of maternal or fetal blood.
p.29
Chemical Testing of Feces
What does a pink color indicate when testing for blood?
The presence of fetal blood.
p.24
Laboratory Tests for Diarrhea Differentiation
What is the purpose of a centrifuge in fecal analysis?
To perform a hematocrit or gravimetric assay.
p.28
Laboratory Tests for Diarrhea Differentiation
What principle does the occult blood test rely on?
Pseudoperoxidase activity of Hg liberates O2 from H2O2 to oxidize guaiac reagent.
p.10
Macroscopic and Microscopic Stool Examination
What colors of stool indicate bile duct obstruction?
Pale yellow, white, gray.
p.17
Specimen Collection Techniques
What should be avoided 72 hours prior to FOBT collection?
Vitamin C, iron, red meats, horseradish, melons, raw broccoli, cauliflower, radishes, and turnips.
p.10
Macroscopic and Microscopic Stool Examination
What conditions can cause mucus or blood-streaked mucus in stool?
Colitis, dysentery, malignancy, constipation.
p.20
Fecal Fat Testing Methods
What is the purpose of quantitative fecal fat testing?
It is a confirmatory test for steatorrhea.
p.13
Specimen Collection Techniques
What is the first step in the muscle fiber microscopy procedure?
Emulsify a small amount of stool in 2 drops of 10% eosin in alcohol.
p.9
Macroscopic and Microscopic Stool Examination
What does the brown color in stool indicate?
The presence of stercobilinogen, which converts to urobilin.
p.16
Chemical Testing of Feces
List the descending order of sensitivity of indicators for FOBT.
Benzidine, Ortho-tolidine, Gum guaiac.
p.15
Chemical Testing of Feces
What type of testing is used to measure fecal fat?
Quantitative Fecal Fat Testing.
p.21
Fecal Fat Testing Methods
What is a key advantage of Near-Infrared Reflectance Spectroscopy (NIRA)?
It requires less stool handling.
p.3
Diarrhea Classification and Mechanisms
What is diarrhea defined as?
An increase in daily stool weight above 200 g with increased liquidity and frequency of more than three times per day.
p.27
Diarrhea Classification and Mechanisms
What causes osmotic diarrhea related to carbohydrates?
Inability to reabsorb carbohydrates or lack of digestive enzymes.
p.24
Fecal Fat Testing Methods
What is Sudan III used for?
For staining in microscopy.
p.6
Altered Motility in Digestive Disorders
What is the hallmark of early dumping syndrome?
Rapid gastric emptying (RGE) occurring 10-30 minutes or less than 35 minutes after a meal.
p.24
Fecal Enzymes and Carbohydrate Testing
What technique is used for measuring fecal elastase-1?
Immunoassay, specifically the ELISA technique.
p.12
Laboratory Tests for Diarrhea Differentiation
What is the purpose of fecal leukocytes microscopy?
It is a preliminary test for invasive bacterial pathogens.
p.14
Fecal Fat Testing Methods
What is added to the emulsified stool on the slide during the procedure?
One drop of 95% ethyl alcohol and two drops of saturated Sudan III in 95% ethanol.
p.23
Fecal Fat Testing Methods
What is the formula for calculating fecal fat in grams per 24 hours for individuals under 15 years old?
[0.1939 x (acid steatocrit in percent as a whole number)] - 0.2174.
p.5
Diarrhea Classification and Mechanisms
How are electrolytes affected in secretory diarrhea?
Electrolytes are increased.
p.12
Specimen Collection Techniques
What is added to the slide after placing the stool sample?
2 drops of Loffler methylene blue.
p.26
Fecal Enzymes and Carbohydrate Testing
What is the testing method for Elastase I?
ELISA using monoclonal antibodies.
p.17
Specimen Collection Techniques
What is important to remember about the kits used for FOBT?
Kits should not be rehydrated or dried prior to adding H2O2 to prevent false positive reactions.
p.20
Fecal Fat Testing Methods
What is the gold standard method for measuring fecal fat?
Van de Kramer titration with sodium hydroxide to the neutral point.
p.13
Laboratory Tests for Diarrhea Differentiation
What is the purpose of emulsifying stool in 10% eosin?
For the diagnosis and monitoring of pancreatic insufficiency.
p.5
Laboratory Tests for Diarrhea Differentiation
What are common fecal tests for diarrhea?
Stool cultures, ova and parasite examinations, rotavirus immunoassay, fecal leukocytes, microscopic fecal fats, muscle fiber detection, qualitative and quantitative fecal fats, trypsin screening, Clinitest, D-xylose/lactose tolerance test, fecal electrolytes, pH, osmolality.
