Wk 6: GI highlights Flashcards
Choice of H. pylori test depends whether patient requires ________________to evaluate symptoms or for surveillance (such as to exclude malignancy)
upper endoscopy
Start with ____________ testing to identify active H. pylori infection (______ antigen or ______ breath test)
non-invasive (stool or urea )
List 2 Important factors that reduce sensitivity of H. pylori testing (increase false negatives)
1) Recent Proton Pump Inhibitor (PPI)/bismuth/antibiotic use
2) Active peptic ulcer bleeding
H. pylori produces __________, which breaks down __________ to produce CO2 and ammonia
urease; urea
Stool antigen test/assay (for H. pylori): How does it work?
Uses monoclonal antibodies specific for H. pylori antigens
True or false: Both the urea breath test and stool antigen test for H. pylori have good sensitivity/specificity
True
1) What H. pylori test cannot distinguish between active and past infection?
2) When is this test not recommended?
1) Serology (blood) test
2) Populations w. low prevalence of H. pylori (much of U.S.)
What test detects anti-H. pylori antibodies (IgG) using ELISA test?
Serology (blood) test?
Microbiologic Culture:
1) How long does it take?
2) Most specific, and _____ sensitivity because H. pylori is difficult to isolate with culture
3) Added benefit of being able to determine ________________ to guide treatment
1) Several weeks
2) low
3) antibiotic susceptibility
What two things identify active H. pylori infection?
Urea breath test/stool antigen tests and endoscopy-based testing
True or false: H. pylori serology does not distinguish active and past infection
True
List 3 things antibodies develop against with celiac
1) Gliadin
2) Endomysium
3) Tissue transglutaminase (tTG)
1) Celiac is an _________ disorder triggered by environmental allergen (dietary gluten)
2) Presence of gluten-derived peptides (e.g., gliadin) triggers mucosal inflammation of the ______________
immune; small intestine
Celiac testing:
1) Is ideally done while patient is on a _________________ diet
2) What two tests are used?
1) gluten-containing
2) Positive celiac serology + positive small bowel biopsy
List and describe the 2 types of testing for Celiac
1) Serology (Blood test): performed in all patients suspected of CD
2) Biopsy: Upper endoscopy with duodenal (small bowel) biopsy
In most patients, the diagnosis of Celiac is established by what 2 things?
Positive celiac serology + positive small bowel biopsy
1) What are 2 types of autoantibody celiac tests?
2) What are 2 types of antibodies targeting gliadin tests?
1) Anti-tissue transglutaminase antibodies + Anti-endomysial antibody
2) Anti-gliadin antibodies (Not recommended) + Deamidated gliadin peptide
1) What is the preferred test for celiac disease in adults?
2) What else can be used?
1) tTg-IgA (an anti-tissue transglutaminase antibody)
2) tTg-IgG (or DGP-IgG)
1) What can be useful as a test in patients with potential Celiac with overall decreased IgA’s?
2) What test is highly sensitive and specific for celiac disease?
1) DGP-IgG
2) Anti-tissue transglutaminase antibodies
What ages should be screened for CRC?
ages 45*-75
True or false: any abnormal screening test for CRC (other than colonoscopy itself) requires follow-up with a timely colonoscopy
True
Average-risk individuals aged ≥ 45 years CRC screening:
1) What should be done annually?
2) What should be done every 1-3 years?
3) What should be done every 10 years?
1) gFOBT + FIT
2) Fecal DNA test (with FIT every 1–3 years)
3) Colonoscopy every 10 years
There are a variety of FOBTs with varying sensitivity/specificity for CRC; list 3
1) Guaiac-based fecal occult blood tests (gFOBT)
2) Fecal immunochemical test (FIT)
3) Multitarget stool DNA test with FIT
What test requires 3 consecutive stool samples and is performed annually?
Guaiac-based fecal occult blood (gFOBT) (for CRC)
Guaiac-based fecal occult blood (gFOBT):
1) What IDs hemoglobin?
2) Frequency?
3) What does it require?
1) Blue paper
2) Annually
3) 3 consecutive stool samples
Guaiac-based fecal occult blood (gFOBT): What can affect it?
Diet and some medications
Guaiac-based fecal occult blood (gFOBT):
1) What can cause false positives?
2) What can cause false negatives?
1) Red meat [stop for 3d]
2) Vitamin C [high doses]
Fecal immunochemical test (FIT) for blood:
1) Frequency?
2) What does it require?
3) Does the pt need to change diet/ meds?
1) Annually
2) 1 stool sample [small]
3) No restrictions to medications or diet
1) Compare the sensitivity of gFOBT to FIT for CRC/advanced adenomas
2) Which test is preferred?
1) FIT has superior sensitivity
2) FIT is preferred
Cell-free DNA (cfDNA) tests are an example of what?
Emerging CRC screening tests
List the 3 categories of pancreatic enzymes
1) Proteolytic enzymes
2) Lipolytic enzymes (lipase)
3) Amylolytic enzymes (amylase)
What are the diagnostic criteria for pancreatitis?
At least 2 of the following
1) Acute onset of persistent, severe, epigastric pain often radiating to the back
2) Elevation in serum lipase or amylase to ≥3 times the upper limit of normal
3) Or characteristic findings of acute pancreatitis on imaging (contrast-enhanced CT, MRI, or transabdominal ultrasonography)
-Diagnosis can be made without imaging if pt has characteristic pain + sufficient lipase/amylase elevation
1) What does amylase hydrolyze?
2) What is the sensitivity? Explain
3) What is the specificity?
1) Carbohydrates
2) Limited (false negatives)
-Can be falsely negative 50% of hypertriglyceridemia-associated pancreatitis cases.
-Dx can be missed in patients >24 hours after onset.
3) Good but some limitations (false positives)
-Not specific
Lipase:
1) What does it hydrolyze?
2) Compare the duration of elevations to amylase
3) Compare the window of detection
1) Triglycerides
2) Elevations occur earlier and last longer than amylase)
3) Greater window for detection (esp. helpful in evaluating pts presenting >24 hrs after)
Lipase:
1) Describe the sensitivity
2) Describe the specificity
1) Good/superior to amylase; high sensitivity for acute pancreatitis
-Alcoholic pancreatitis marker (more sensitive)
2) Good but some limitations (false positives)
Amylase:
1) Describe the elevation curve
2) Describe the sensitivity
1) Shorter window of detection, not elevated later in course
2) Less sensitive than lipase; false negatives
Lipase:
1) Describe the elevation curve
2) Describe the sensitivity
1) Elevations occur earlier and last longer than amylase
-Greater window for detection
2) Higher sensitivity than amylase, esp. for alcoholic pancreatitis and pts presenting >24 hrs after onset
