pancreatitis%20-%20chronic
PANCREATITIS - CHRONIC
Chronic pancreatitis develops from irreversible scarring sustained by the pancreas from prolonged inflammation.
Signs and symptoms include abdominal pain that is epigastric in location that radiates to the back and frequently occurs at night or after meals, symptoms of fat, protein & carbohydrates maldigestion that become apparent with advanced chronic pancreatitis and presence of diarrhea.
Chronic pancreatitis results in destruction of alpha and beta cells which gives rise to deficiencies of both insulin and glucagon.

Diagnosis

Principles of Diagnostic Testing

  • Stage & etiology of pancreatitis will determine the accuracy of the diagnostic tests used
  • In many instances, the clinical presentation is enough to propose a tentative diagnosis especially w/ alcohol-related pancreatitis
  • Consider starting w/ tests which are safe & inexpensive but detect only advanced disease:
    • Plain abdominal x-rays
    • Abdominal ultrasound (US)
    • Serum glucose & trypsin, fecal fat, fecal elastase
  • When the above tests do not aid in diagnosis, consider using more sensitive, but more costly or risky tests:
    • Computed tomography (CT) scan
    • Endoscopic US
    • Endoscopic retrograde cholangiopancreatography (ERCP)
    • Magnetic resonance cholangiopancreatography (MRCP)
  • Direct pancreatic function testing, if available, may also be considered if CT scan does not yield a diagnosis, before ERCP or MRCP is done

Physical Examination

There is no physical exam finding that is specific for chronic pancreatitis

  • Patients usually look well-nourished
  • May note mild to moderate abdominal tenderness
  • In severe disease, weight loss & malnutrition become more pronounced
  • Other findings may include jaundice, a palpable abdominal mass which may be a pancreatic pseudocyst, a palpable spleen or signs of concurrent chronic alcoholic liver disease

Laboratory Tests

Pancreatic Function Tests

Serum Trypsin

  • Very low levels are specific for chronic pancreatitis, & may be seen in advanced disease w/ steatorrhea
  • Inexpensive & risk-free

Stool Chymotrypsin

  • Abnormal in most patients w/ advanced chronic pancreatitis & steatorrhea
  • May be falsely positive in other malabsorptive conditions, severe malnutrition & diarrheal diseases that result in a dilute stool

Stool Elastase

  • Easy to measure; level <100 mcg/g stool corresponds to advanced chronic pancreatitis
  • Accurate in patients w/ steatorrhea, but less accurate in earlier disease

Direct Hormonal Stimulation w/ Secretin

  • Damage to the pancreas may need to be substantial (30-50%) before tests become reliably positive
  • Most sensitive test available
  • Test is expensive, not readily available & has not been standardized

Measurement of Pancreatic Enzyme Action

Bentiromide Test

  • Urine metabolite used to measure chymotrypsin w/in the gut lumen, accurate only in advanced disease

Pancreolauryl Test

  • Urine metabolite used to measure pancreatic arylesterases w/in the gut lumen, accurate only in advanced disease

Fecal Fat

  • Fat maldigestion arises when only about 10% of pancreatic lipase secretory capacity is left
  • Test requires strict measurement of dietary fat & complete stool collection for 72 hours, which may make it difficult to perform

Pancreatic Histology

  • Gold standard for diagnosis
  • Routine biopsy is risky & only rarely performed
  • Changes may not be uniform throughout the gland so a single random tissue sampling may not be diagnostic

Imaging

Abdominal X-rays

  • Diffuse pancreatic calcifications are considered specific for chronic pancreatitis
    • Calcifications often occur in late-onset disease & may wax & wane over time
  • Calcifications are more commonly seen in alcoholic, hereditary, late-onset idiopathic & tropical pancreatitis

Abdominal Ultrasound (US)

  • Findings consistent w/ chronic pancreatitis include the following:
    • Pancreatic duct dilation, presence of ductal stones, calcifications or pseudocysts
    • Changes in parenchymal echotexture & gland size
  • Mild changes are less specific
  • Overlying bowel gas may make adequate visualization of the pancreas difficult

Computed Tomography (CT) Scan

  • May be used as one of the 1st tests to detect chronic pancreatitis since it is noninvasive & has relatively good sensitivity for diagnosing moderate-severe chronic pancreatitis
  • Has a test sensitivity of 75-90% & specificity of at least 85%
  • Pathognomonic findings include calcifications w/in the pancreatic ducts or parenchyma &/or dilated main pancreatic ducts together w/ parenchymal atrophy
  • CT scanning is able to identify most complications of chronic pancreatitis & other abdominal pathologies that may present w/ signs & symptoms similar to those of chronic pancreatitis

Endoscopic Ultrasound (US)

  • Diagnosis is based on abnormalities in the pancreatic duct &/or parenchyma
  • Eliminates imaging problems encountered w/ abdominal US (eg overlying bowel gas)
  • May be used to obtain pancreatic tissue &/or secretions
  • Sensitivity & specificity in early disease requires further evaluation

Identify Presence of Treatable Complications

  • Pain is the most common symptom of chronic pancreatitis that will need medical care
  • Therefore, the initial evaluation should include the identification of conditions that are treatable

Computed Tomography (CT) Scan

  • Can be used to identify fluid collections, pseudocysts, mass lesions or pancreatic duct dilation
  • Duodenal or bile duct obstruction may also be identified

Barium Radiography or Endoscopic Retrograde Cholangiopancreatography (ERCP)

  • May be necessary to define obstructions
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