Laboratory Assessment of Pancreatic Diseases

Laboratory Assessment of Pancreatic Diseases

Laboratory Assessment of Pancreatic Diseases

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Acute Pancreatitis Labs - Enzyme Power Play

  • Serum Amylase:
    • Rises: 2-12 hrs; Peaks: 24 hrs; Normalizes: 3-7 days
    • Diagnostic if >3x ULN (Upper Limit of Normal)
    • Less specific (e.g., mumps, renal failure)
  • Serum Lipase:
    • Rises: 4-8 hrs; Peaks: 24 hrs; Normalizes: 8-14 days
    • Diagnostic if >3x ULN
    • More specific & sensitive; elevated longer.
    • 📌 Lipase: Lasts Longer, Leading diagnostic.
  • Other Key Markers:
    • ↑ WBC (leukocytosis), ↑ Hct (initially, then ↓ if hemorrhage)
    • ↑ LDH, ↑ CRP (>150 mg/L at 48h suggests severity)
    • ↓ $Ca^{2+}$ (hypocalcemia - poor prognosis)
    • ↑ Glucose
    • ↑ BUN/Creatinine (renal function)

⭐ ALT >150 U/L strongly suggests gallstone pancreatitis.

Chronic Pancreatitis Tests - Function Under Fire

Evaluates exocrine pancreatic insufficiency (EPI).

  • Direct Tests (Invasive, Gold Standard):
    • Secretin-CCK Test: Measures bicarbonate & enzyme output post-stimulation.
    • Endoscopic Pancreatic Function Test (ePFT): Endoscopic fluid collection.
  • Indirect Tests (Non-invasive, Screening):
    • Fecal Elastase-1 (FE-1):
      • Normal: >200 µg/g stool.
      • Severe EPI: <100 µg/g.
    • Fecal Fat:
      • Sudan Stain (Qualitative).
      • 72-hr collection: >7 g/day abnormal (Steatorrhea gold standard).
    • Serum Trypsinogen: ↓ in severe EPI.
    • C13-Mixed Triglyceride Breath Test.

⭐ Fecal Elastase-1 is the most sensitive and specific indirect test for pancreatic exocrine insufficiency, unaffected by enzyme replacement therapy (PERT).

Pancreatic Cancer Markers - Tumour Trail Tidings

  • CA 19-9 (Carbohydrate Antigen 19-9):
    • Primary serum marker for pancreatic ductal adenocarcinoma (PDAC).
    • Monitors therapy response, aids in detecting recurrence.
    • Not for screening (low specificity/prevalence).
    • Levels > 1000 U/mL suggest unresectability/metastasis.
  • CEA (Carcinoembryonic Antigen):
    • Less sensitive/specific than CA 19-9 for PDAC.
    • Elevated in ~50% of cases; often used with CA 19-9.
    • Prognostic value; monitors recurrence.

⭐ CA 19-9 is absent in Lewis antigen (a-/b-) negative individuals (~5-10% population), leading to false negatives.

Pancreatic Cyst Fluid Analysis - Lesion Clues

  • Amylase: High in pseudocysts; low in SCN, MCN, IPMN.
  • CEA:
    • 192 ng/mL: Mucinous (MCN/IPMN).

    • < 5 ng/mL: SCN, pseudocyst.
  • Glucose: < 50 mg/dL suggests malignancy.
  • String Sign: Positive in mucinous cysts (viscous).
  • Cytology: Malignant cells; low sensitivity.
  • Molecular: KRAS (MCN, IPMN, PDAC), GNAS (IPMN).

⭐ CEA > 192 ng/mL strongly suggests a mucinous cyst (MCN/IPMN), guiding further management.

High‑Yield Points - ⚡ Biggest Takeaways

  • Serum amylase & lipase are crucial for acute pancreatitis; lipase is more specific and elevated longer.
  • Elevated amylase can be non-pancreatic (e.g., salivary disorders, renal failure).
  • Fecal elastase-1 is the most sensitive test for exocrine pancreatic insufficiency.
  • CA 19-9 is a tumor marker for pancreatic cancer, but not for screening.
  • Genetic testing (PRSS1, SPINK1, CFTR) is vital for hereditary pancreatitis.
  • Secretin stimulation test is gold standard for exocrine function but invasive.

Practice Questions: Laboratory Assessment of Pancreatic Diseases

Test your understanding with these related questions

According to endoscopic ultrasound (EUS) criteria for chronic pancreatitis, the main pancreatic duct is considered dilated when its diameter is:

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Flashcards: Laboratory Assessment of Pancreatic Diseases

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Which cystic neoplasm of the pancreas has low levels of CEA and amylase?_____

TAP TO REVEAL ANSWER

Which cystic neoplasm of the pancreas has low levels of CEA and amylase?_____

Serous cystadenoma

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