LABORATORY TESTS Flashcards
It is a test for Steatorrhea
Test for Fecal Fat
the presence of increase fats in
stool
Steatorrhea
Fecal characteristic of Steatorrhea
Greasy; foul odor; spongy consistency
Fecal volume of Steatorrhea
Increased
Causes of Steatorrhea
Pancreatic insufficiency
Malabsorption, Maldigestion
Absence of bile
inadequate intestinal absorption of processed foodstuffs despite normal digestive ability
MALABSORPTION
an inability to convert foodstuffs
in the gastrointestinal tract into readily absorbable substances
MALDIGESTION
Qualitative Fecal Fat Stain
Neutral Fat Stain
Split Fat Stain
Stain for Triglycerides
Neutral Fat Stain
Procedure for Neutral Fat Stain
emulsified stool + 95% ETOH + Sudan
III
Value of Steatorrhea in Neutral Fat Stain
≥ 60ORANGE DROPLETS/HPF
Stain for total fat content (including Fatty acids, soaps/fatty acid salts, and cholesterol)
Split Fat Stain
Procedure for Split Fat Stain
stool + 36% acetic acid + Sudan III +
Heat
Value of Steatorrhea in Split Fat Stain
100 droplets that are 6-75 um in
size
Neutral Fat Stain is NORMAL
Split Fat Stain is INCREASED
MALABSORPTION
Neutral Fat Stain is INCREASED
Split Fat Stain is NORMAL
MALDIGESTION
Gold standard quantitative test
for fecal fat content
Van De Kamer Test
Collection Considerations for Van De Kamer Test:
Requires the collection of ____ specimen.
at least a 3 days
Collection Considerations for Van De Kamer Test:
The patient must maintain a regulated intake of fat of ____ before and during the collection period
100 g/day
Collection Considerations for Van De Kamer Test:
The specimen is collected in a _____ container like paint cans
large, pre-weighed
Collection Considerations for Van De Kamer Test:
The entire fecal collection is ____ and ____ (e.g., using a mechanical
shaker).
weighed and homogenized
Principle of Van De Kamer Test
Titration or titrimetric method
Reagents used of Van De Kamer Test
Sodium hydroxide (naoh)
In the titrimetric method, ____ and ____ are converted to ____ before extraction.
neutral fats and soaps
fatty acids
Because the titrimetric method is unable to recover medium-chain fatty acids completely, it measures approximately ___ of the total fecal lipid content.
80%
The fat content is reported as grams of fat or the coefficient of fat retention per ____
Reference values based on a ___ are 1 to 6 g per day or a coefficient of fat retention of at least ____
24 hours
100 g/d intake
95%
Normal value if px undergoes
standard diet:
1 to 6 g per day
this is useful for children when standard fat diet is used.
Van De Kamer Test
Disadvantage of Van De Kamer Test
time consuming and uses corrosive and flammable solvents
A test that is useful to differentiate
malabsorption and maldigestion
D-xylose test
D-Xylose is a ____ that does not need to be ____ but does need to be ____ to be present in the urine
pentose sugar
digested
absorbed
The xylose absorption test involves the patient’s ingestion of a ____, followed by the collection of a blood sample after ____ urine specimen
dose of xylose
2 hours and a 5-hour
If D-xylose result is low/abnormal, the result indicates a ___
malabsorption
Presence of ≥3 neutrophils/HPF Indicates invasive condition
Fecal Leukocytes
Presence of at least 1 Neutrophil per OIF is significant (Strasinger)
Fecal Leukocytes
Wet preparation of Fecal Leukocytes
Stool + Methylene blue
It is the faster procedure but may be
more difficult to interpret
Methylene blue
It is used to differentiate mononuclear cells and PMNs
Methylene blue
A test for fecal WBC that gives a
positive result in an invasive bacterial pathogen
Lactoferrin Latex Agglutination
It remains sensitive in refrigerated and frozen specimens
Lactoferrin Latex Agglutination
Lactoferrin Latex Agglutination is positive in diarrhea with WBC: (5)
Salmonella, Shigella, Campylobacter, Yersinia, & entero-invasive E. coli
Lactoferrin Latex Agglutination is negative in diarrhea without WBC: (4)
Staphylococcus aureus and Vibrio spp., viruses, and parasites
Stool stained with either Wright’s or Gram stains provides permanent slides for evaluation.
Dried preparation
Occult means “hidden”
Screening test for colon cancer
Fecal Occult Blood Test
Significant value of Fecal Occult Blood Test
> 2.5ml blood / 150g stool
Sample must be obtained from the ___ portion of the stool to avoid ____ from ____ contamination
center
false positive
external
Chromogen used for Fecal Occult Blood Test (3)
Benzidine
Guaiac
Otoluidine
Contrary to most chemical testing, the least sensitive reagent, _____, is preferred for routine testing
Guaiac
Reaction is based on Pseudoperoxidase activity of Hemoglobin
Fecal Occult Blood Test
Aspirin and other NSAIDs will have a result of?
False positive
Aspirin and other NSAIDs should be avoided for
7 days
Red meats, horseradish, melons,
raw broccoli, cauliflower, radishes,
& turnips will have a result of?
False positive
Red meats, horseradish, melons,
raw broccoli, cauliflower, radishes,
& turnips turnips should be avoided for
3 days
Reducing agent such as Vitamin C will have a result of?
False positive
Reducing agent such as Vitamin C should be avoided for
3 days
Iron supplements containing vitamin C will have a result of?
False Negative
Iron supplements containing vitamin C will have a result of?
False Negativewill have a result of?
Failure to allow stool samples to soak into the filter paper slide for 3 to 5 minutes before adding developer will have a result of?
False Negative
Applying a thick smear of stool sample on the test card will have a result of?
False Negative
Presence of more than 10 undigested muscle fibers are associated with biliary obstruction, cystic fibrosis, and gastrocolic fistulas
Muscle fibers
Increase excretion of muscle
fibers in feces
Creatorrhea
Partially digested fibers
Fibers exhibit striations in only one direction
Patient will undergo in a meat diet
Procedure in Creatorrhea
Procedure of Creatorrhea
Emulsified stool + 10% eosin in alcohol → coverslip and stand for 3 mins then observed under HPF for 5 minutes
Digested fibers
Fibers have no visible striations
Undigested fibers
Fibers have visible striations
running both vertically and horizontally
A test for Fetal hemoglobin
APT Test/ Alkali Denaturation Test/ Downey Test
Used to Differentiate fetal blood from maternal blood
APT Test/ Alkali Denaturation Test/ Downey Test
Discovered by Leonard Apt
APT Test/ Alkali Denaturation Test/ Downey Test
Specimen for APT Test/ Alkali Denaturation Test/ Downey Test
infant stool, vomitus, emesis, or
gastric aspirate
Reagent used for APT Test/ Alkali Denaturation Test/ Downey Test
1% NaOH
Pink supernatant in APT Test/ Alkali Denaturation Test/ Downey Test:
fetal blood with Hemoglobin F
Yellow-brown supernatant in APT Test/ Alkali Denaturation Test/ Downey Test:
maternal blood with Hb A
Enzymes supplied to the gastrointestinal tract by the pancreas are essential for digesting
dietary proteins, carbohydrates, and fats
Fecal Enzymes
Decreased production of these enzymes (pancreatic insufficiency) is associated with disorders such as chronic pancreatitis and cystic fibrosis. Steatorrhea occurs, and undigested food appears in the feces
Fecal Enzymes
Detects trypsin enzyme
(absent of trypsin is associated with cystic fibrosis)
X-ray Film test
____ of trypsin has been
screened for by exposing x-ray
paper to stool _____ in
water
Absence
emulsified
When trypsin is present in the stool, it digests the ____ on the paper, leaving a clear area
gelatin
Inability to digest the gelatin
indicates a deficiency in
trypsin production
More resistant to intestinal degradation and is a more sensitive indicator of less severe cases of pancreatic insufficiency
Chymotrypsin
Chymotrypsin is stable in fecal specimen up to
10 days at room temperature
Measured by spectrophotometry
Chymotrypsin
An enzyme form produced by the pancreas and accounts about 6% of all secreted pancreatic enzyme
Elastase 1
Sensitive and specific test for
exocrine pancreatic insufficiency
Elastase 1
The test is specific in differentiating pancreatic from nonpancreatic causes inpatients with steatorrhea
Elastase 1
T/F
It is affected by motility
disorders or mucosal defects
FALSE
NOT AFFECTED
It is measured by ELISA
Elastase 1
The ELISA test uses ____ against human pancreatic elastase-1;
therefore, the result is specific for ____ and not affected by
pancreatic enzyme replacement therapy
monoclonal antibodies
human enzyme
Significant for assessing lactose intolerance
Fecal carbohydrates
Fecal carbohydrates normal pH stool
7-8
Fecal carbohydrates with stool pH and Carbohydrate Disorders:
pH <5.5
a test for reducing sugar
(carbohydrate) in Fecal carbohydrates
Clinitest
A result of ___ indicates carbohydrate intolerance
≥0.5 g/dl
