Pancreatitis%20-%20chronic Diagnosis

• Inquire about patient’s past medical history (eg medication use, history of maldigestion/malnutrition, weight loss, or fractures, previous episodes of acute pancreatitis, DM, renal disease, and diseases associated with cystic fibrosis such as sinusitis, lung disease, or male infertility), family history (eg pancreatitis, pancreatic cancer, DM, cystic fibrosis), and social history (eg alcohol use, smoking)  

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 and 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

Pancreatic Function Tests

• Complementary tests in diagnosing exocrine pancreatic insufficiency in patients not yet diagnosed with chronic pancreatitis 

Stool Elastase

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

Stool Chymotrypsin

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

Serum Trypsin 

• Very low levels are specific for chronic pancreatitis, and may be seen in advanced disease with steatorrhea
• Inexpensive and risk-free, though not currently used due to poor correlation with imaging results and reports of elevated levels in nonpancreatic pain syndromes

Cholecystokinin (CCK) Stimulation Test

• Direct acinar cell function stimulation that measures trypsin and/or lipase  
• Detects subtle exocrine pancreatic insufficiency  
• Not readily available and requires specialized lab testing

Secretin Stimulation Test

• Direct ductal cell function stimulation that measures bicarbonate  
• Damage to the pancreas may need to be substantial (30-50%) before tests become reliably positive
• Test is expensive, not readily available and prone to errors in measurement  

Measurements of Pancreatic Enzyme Action

Fecal Fat

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

Bentiromide Test 

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

Pancreolauryl Test

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

Genetic Testing

• Identifies pancreatitis-related disorders (eg CFTR variants with a CFTR-related disorder or cystic fibrosis), aids in decision making and treatment choices, and helps prevent irreversible chronic pancreatitis  
• Indicated in the following: Uncertain etiology, age <35 years old, family history of pancreatic diseases or disease persistence after treatment intervention  
• At a minimum, CFTR, CTRC, SPINK1, and PRSS1 gene mutation analysis should be evaluated in patients with idiopathic chronic pancreatitis

Pancreatic Histology

• Gold standard for diagnosis in high-risk patients when clinical evidence is strong for chronic pancreatitis but imaging tests are inconclusive
• Routine biopsy is risky and only rarely performed
• Changes may not be uniform throughout the gland so a single random tissue sampling may not be diagnostic

Abdominal X-rays

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

Abdominal Ultrasound (US)

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

Computed Tomography (CT) Scan

• Used as one of the 1st-line cross-sectional imaging tests aside from magnetic resonance imaging (MRI) to detect chronic pancreatitis since it is noninvasive and has relatively good sensitivity for diagnosing moderate-severe chronic pancreatitis
• Has a test sensitivity of 75-90% and specificity of at least 85%
• Pathognomonic findings include calcifications within the pancreatic ducts or parenchyma and/or dilated main pancreatic ducts together with parenchymal atrophy
• CT scanning is able to identify most complications of chronic pancreatitis and other abdominal pathologies that may present with signs and symptoms similar to those of chronic pancreatitis

Endoscopic Retrograde Cholangiopancreatography (ERCP)

• Considered the “de facto” gold standard because it is currently the most specific and sensitive test of pancreatic structure
• Useful for patients in whom other tests are nondiagnostic or unavailable
• Diagnosis is based on abnormalities seen in the main pancreatic duct and its branches
• Pathognomonic findings consist of a markedly dilated pancreatic duct with alternating strictures (“chain-of-lakes” appearance) 
• Advantage is therapy may also be administered eg pancreatic duct stenting or stone extraction; main disadvantage is that it is the riskiest exam for chronic pancreatitis  
• Finer changes seen in early disease are often subject to inter-observer interpretation variability

Endoscopic Ultrasound (EUS)

• A sensitive imaging modality for diagnosing chronic pancreatitis, specifically its early stages 
• Due to its invasiveness and lack of specificity, EUS should only be used if the diagnosis is uncertain after performing a cross-sectional imaging 
• Diagnosis is based on abnormalities in the pancreatic duct and/or parenchyma
• Eliminates imaging problems encountered with abdominal US (eg overlying bowel gas)
• May be used to obtain pancreatic tissue and/or secretions

Magnetic Resonance Imaging (MRI) with Magnetic Resonance Cholangiopancreatography (MRCP)

• Detailed images of the pancreas are seen similar to a CT scan  
• Test is noninvasive and does not require sedation
• Secretin-enhanced MRCP may be performed in patients with high clinical suspicion but cross-sectional imaging or EUS is non-confirmatory  
  • Can identify subtle abnormalities in the duct, eg an ectatic duct or dilated branches

• 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
  • The biochemical and radiological findings of chronic pancreatitis do not correlate well with the intensity of patient’s pain
• 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 ERCP may be necessary to define obstructions