L20 Investigations of GI disorders Flashcards
RR of amylase levels?
28-100 IU/L
Which of the following about amylase is correct?
A. Amylase of >1000 IU/L is diagnostic of acute pancreatitis
B. Amylase levels can reflect the severity of the pancreatitis
C. Amylase levels can reflect the prognosis of the pancreatitis
D. Urine amylase can be used to confirm acute pancreatitis but is elevated for a shorter time than plasma amylase
E. Lipase can be used to confirm acute pancreatitis but is elevated for a shorter time than plasma amylase
A only
B and C: no!
D and E: both are elevated for a longer time than plasma amylase
What is Ranson’s score used for? (1)
Name the parameters of the Ransons score. (10)
Used to establish a prognosis for acute pancreatitis.
Present initially: LEGAL - LDH >350 IU/L - agE >55 - Glucose >10 mmol/L - AST <250 IU/L - Leukocytes (WBC) >16 x 10^9
Develop during the first 24 hours C HOUR - Ca < 2mmol/L - Hct drop >10% - pO2 <8kPa - Urea > 16mmol/L - Albumin <30g/L
What to do to find out the etiology of increased amylase? What are the expected findings?
USG abdomen
- swollen pancreas: acute pancreatitis
- gallstone: dilated biliary tree
Name the 5 categories of conditions associated with increased amylase level.
- Pancreatic
- Retroperitoneum inflammation
- Non-abdominal
- Reduced clearance
- Drugs
List 4 pancreatic causes for elevated amylase levels.
- Pancreatitis
- CA pacnreas
- Pancreatic pseudocyst - confirmed by USG abdomen
- Trauma
List 2 causes of retroperitoneal inflammation causing elevated amylase levels.
- PPU/ perforated bowel e.g. duodenum
- Peritonitis
(many causes of acute abdomen)
List 2 non-abdominal causes for elevated amylase levels.
- Salivary gland pathology: salivary glands also produce amylase (S-type)
- Ketoacidosis: unknown source, but not of pancreas origin (increase S-type)
What is the equation of amylase clearance?
What is the normal %?
% in pancreatitis?
Amylase clearance =
(Amylase in urine/ Amylase in blood) / (Creatinine in urine/ Creatinine in blood)
Normal amylase: creatinine clearance ratio (ACCR) < 1%
Pancreatitis >2%
List the cause for reduced clearance of amylase that causes an elevated amylase level.
Macroamylassemia: amylase bound by a macromolecule (e.g. AutoAb), reducing amylase clearance
List 2 drugs that will induce elevated amylase levels.
- Azathioprine (immunosuppressant), salicylate
- Sulphonamides (Abx)
- Tetracyclines (Abx)
- Valproic acid (anti-epileptics)
Name the 4 conditions associated with persistent amylase elevation.
- Pancreatic pseudocyst
- a collection of amylase-rich fluid enclosed in a well-defined wall/fibrous/granulation tissue
- commonly after acute/ chronic pancreatitis - Macroamylassemia
- degree of elevation is much lower than 1 - Chronic pancreatitis
- slight increase/ normal amylase level - Renal insufficiency
- elevated together with other parameters e.g. PO4
Ulcers can be categorized as esophageal, gastric, and duodenal ulcers.
How can gastric ulcers be differentiated from duodenal ulcers? (5)
- Food
- GU: aggravated pain
- DU: relieved pain - H.pylori
- GU: 65-95%
- DU: 80-95% - Malignant potentional
- GU: +
- DU: - - Biopsy
- GU: antrum +, ulcer edge +
- DU: antrum +, ulcer edge - - Rescope (to avoid missing malignancies)
- GU +
- DU -
H.pylori has __________ that converts urea into _________ at the antrum.
Urease;
NH3 (alkaline)
Treatment for GU/DU?
Triple therapy
- PPI
- Clarithromycin
- Amoxycillin
Malignancies of the small bowel?
- Carcinoid tumor (MC small bowel tumor)
2. Carcinoma (rare)
What are the possible effects of cancer in bowels?
- Ulceration
- chronic bleeding > anemia + FOBT - Obstruction of the lumen
- Secretions
- mucus into the bowel lumen
- tumor-specific substances into blood e.g. CEA in CRC
What are the investigations to be done if suspect GI malignancies?
- Iron profile: IDA
- FOBT (Fecal occult blood test) (SENSA)
- Faecal immunochemical test (FIT)
- Endoscopy: OGD/ colonoscopy if symptomatic
What is the main purpose of FOBT?
For early screening of asymptomatic patients (NOT symptomatic!) to detect CRC.
*** good for excluding subjects without CRC
What is Hemoccult SENSA?
Chemical test based on the peroxidase-like activity of heme, a component of Hb in catalyzing the oxidation of colorless chromogen to blue.
(any heme)
What is Hemoccult ICT?
Immunochemical test based on the binding of polyclonal antibody against the globin portion of non-degraded human hemoglobin
(must be human Hb)
Case 1: 63 year old man with alteration of bowel habit.
Hemoccult SENSA -
Hemoccult ICT -
How to interpret the results?
- The results do not exclude colorectal cancer due o the poor diagnostic sensitivity of the test.
- symptomatic»_space;> go for OGD!
Case 2: 44/F taking aspirin for RA.
Hemoccult SENSA +
Hemoccult ICT -
How to interpret the results?
- Hemoccult SENSA - detect heme from UGIB due to aspirin intake
- ICT is less sensitive and Hb is degraded by bacterial and digestive enzymes before reaching the large. intestine.
Case 3: 42/M routine check-up. The previous evening he had eaten 12 ox steak.
Hemoccult SENSA +
Hemoccult ICT -
How to interpret the results?
- Hemoccult SENSA - heme from red meat, false positive
- ICT only human Hb, no need for special dietary retrictions
Case 4 62/F taking a multivitamin preparations
Hemoccult SENSA -
Hemoccult ICT +
How to interpret the results?
Hemoccult SENSE -ve is a false negative since ascorbic acid/vitamin C is a negative interference of oxidation.
Hemoccult ICT is true positive.
Screening guidelines in HK for age over 50 without prior history of disease (low risk)?
- FOBT for every 1-2 years/
- Flexible sigmoidoscopy every 5 years/
- Colonoscopy every 10 years
Screening guidelines in HK for high-risk group?
- Colonoscopy every 3-5 years at age 40
