Lecture 4 Flashcards
When we speak of exocrine pancreas
what enzymes are produced and what is their location
Amylase, Lipase, Proteases (e.g.,
Trypsinogen)
Acinar cells
Common Conditions Affecting the Pancreas
- Cystic Fibrosis
- Pancreatic Carcinoma
- Pancreatitis
- Steatorrhea
Cystic Fibrosis (CF)
Pathophysiology:
and clinical manifestations
Genetic disorder affecting lungs and digestive system
o Mucus-filled cysts block pancreatic ducts from reaching the duodenum
pts have Chronic lung infections, fat malabsorption due to loss of pancreatic enzymes
Pancreatic Carcinoma
Pathophysiology:
clinical manifestations
Obstruction of ducts, buildup of digestive enzymes
Can lead to pancreatitis and severe pain
Pancreatitis
Pathophysiology:
clinical manifestations
lab findings
Inflammation, enzyme auto-digestion of tissue
-occurs when digestive enzymes are activated in pancreas rather than duodenum= causing auto digestion of pancreatic tissue
Clinical Manifestations:
o Severe abdominal pain, necrosis
o Often related to alcohol abuse or gallstones
Elevated Amylase (Starch breakdown)
and Lipase (Fat digestion)
o Associated with pancreatic tissue damage
Steatorrhea
Pathophysiology:
clinical manifestations
Fat malabsorption due to poor pancreatic exocrine function
-fails to excrete lipase
-excess fat in feces
Clinical Significance:
o Excess fat in feces, greasy stool
Amylase Testing
Clinical Significance:
Measurement Techniques:
-catalyzes starch breakdown and glycogen into simple sugars salivary amylase (S-type) and
pancreatic amylase (P-type)
o Elevated in acute pancreatitis (peaks 24 hrs, returns to normal 3-5 days)
o Chronic pancreatitis: Levels usually lower
o Non-pancreatic causes: Mumps, renal failure
Serum or plasma - heparinized
Coupled Enzyme Reaction (CNPG3 substrate)-looking for increased ABs proportional to amylase activity
o Dry Chemistry (Vitros Method)- measure by reflectance
o Immunoassays (for isoenzyme determination) pancreatic vs salivary amylase
use ABs specific to isoenzymes to measure their concentrations
Lipase Testing
Clinical Significance:
Measurement Techniques:
Elevated in acute pancreatitis
-spin it down if left for too long it can falsely decrease
* More specific than amylase (3-5 days to go down) for acute pancreatic disorders
lipase takes longer to go down
* Serum preferred, plasma can also be used
-elevated levels indicate pancreatic duct obstruction
o Turbidimetric Assays (Triglyceride emulsion substrate)- lipase breaks down triglycerides decreasing turbidity which is then measured with a spectrophotometer= change in turbidity is proportional to the lipase activity
o Colorimetric Assays (e.g., synthetic substrate for lipase) uses a synthetic substrate that releases a colored product when hydrolyzed by lipase. there is an abs change at 580 nm measured which corresponds to lipase activity
o Enzymatic Assays (Coupled reactions for glycerol measurement)
reaction results in measurable product l
lipase hydrolyzes a substrate to release glycerol which is then measured
Additional Laboratory Testing for Pancreatitis
Total Bilirubin: Elevated in biliary obstruction, conjugated increases showing that bile ducts are compromised
o Glucose: Hyperglycemia possible due to impaired endocrine function- diabetes
o Calcium: Hypocalcemia due to fat necrosis due to calcium soap formation
o Liver Enzymes: Elevated with alcohol involvement
o CBC: Leukocytosis with left shift
CT scan to look at gallstones
Pancreatic Function Testing: Fecal Fat Analysis
testing methods
Indicator of fat digestion/absorption issues
o Seen in pancreatic insufficiency, biliary obstruction.
Qualitative: Sudan III staining of stool to visualize fat in stool
o Quantitative: 72-hour stool collection with gravimetric or titrimetric analysis (weigh lipid residue)
Malabsorption: D-Xylose Absorption Test
purpose and method
Differentiate pancreatic vs. intestinal malabsorption
Measure xylose levels in blood or urine after ingestion of D xylose
low levels indicate intestinal malabsorption which rules out pancreatic cause
What can falsely increase serum amylase
Morphine & opiates
Acute pancreatitis
what will amylase look like
↑ 5-8 hrs. after onset of attack, peaks at 24 hrs
serum levels return to normal in 3-5 days
Sources of Error: lipase
Hemolyzed sample falsely ↓ serum lipase (inhibited by hemoglobin
both lipase and amylase rise quickly within 4-5 h of acute pancreatitis attack but lipase stays elevated longer than AMY: up to 8 days in acute pancreatitis
Levels are normal in conditions involving salivary gland
