Pancreatitis Study Guide

📖 Core Concepts Pancreatitis – inflammation of the pancreas, an organ that makes digestive enzymes (amylase, lipase) and hormones (insulin, glucagon). Acute vs. Chronic Acute: sudden onset, usually resolves in days; can be life‑threatening. Chronic: long‑standing damage, irreversible loss of exocrine and endocrine function. Key enzymes – Lipase is more specific for pancreatic injury and stays elevated longer than amylase. Major causes – Gallstones (most common) and heavy alcohol use for acute disease; hypertriglyceridemia, hypercalcemia, medications, genetics for chronic disease. Complications – Early (shock, SIRS, hypocalcemia, renal failure, pleural effusion) and late (pseudocysts, diabetes, exocrine insufficiency, pancreatic cancer). Severity assessment – BISAP score uses 5 simple variables to predict organ failure and mortality. --- 📌 Must Remember Diagnostic threshold: serum amylase or lipase ≥ 3 × the upper limit of normal. Lipase > amylase for specificity and longer half‑life. Imaging timing: contrast‑enhanced CT is most accurate after 48 h for necrosis. Fluid resuscitation: start early with lactated Ringer’s (or saline) – “moderately aggressive.” Pain meds: NSAIDs first for mild pain; IV opioid infusion for severe pain. Nutrition: start oral feeding ASAP if tolerated; otherwise place NG/NJ tube within 48 h. Antibiotics: give only for proven infection or infected necrosis – no prophylaxis. Gallstone pancreatitis: ERCP to clear CBD stones and cholecystectomy during the same admission (or soon after). BISAP components: BUN > 25 mg/dL, impaired mental status, SIRS, Age > 60, Pleural effusion. --- 🔄 Key Processes Diagnosing Acute Pancreatitis Step 1: Check serum amylase or lipase → ≥3 × ULN? Step 2: Obtain imaging (US, CT, MRI, or EUS) showing pancreatic inflammation. Step 3: If 2 of 3 criteria met → diagnosis confirmed. Initial Management (First 24 h) Fluid: Start lactated Ringer’s 250‑500 mL/hr; titrate to urine output ≥ 0.5 mL/kg/h. Pain: Give NSAID (e.g., ibuprofen) → assess; if inadequate, start IV opioid infusion. Nutrition: Offer oral diet if nausea controlled; otherwise place NG/NJ tube within 48 h. Gallstone‑related Intervention Perform ERCP if there’s cholangitis or persistent CBD obstruction. Schedule cholecystectomy before discharge (or within 2 weeks) to prevent recurrence. BISAP Scoring (calculate within 24 h) Assign 1 point for each: BUN > 25 mg/dL, altered mental status, SIRS, age > 60, pleural effusion. Score ≥ 2 → high risk of mortality/organ failure; consider ICU monitoring. --- 🔍 Key Comparisons Acute vs. Chronic Pancreatitis Onset: sudden vs. long‑standing. Pain: acute – severe, radiates to back; chronic – intermittent, may be less intense. → Chronic often presents with weight loss, steatorrhea, diabetes. Serum Amylase vs. Lipase Specificity: Lipase > Amylase. Duration: Lipase stays elevated longer (helps when presentation is delayed). Imaging Modality Ultrasound: cheap, best for gallstones, limited by gas. CT (contrast, >48 h): best for necrosis & fluid collections. MRI: superior ductal anatomy, no radiation. Pain Control NSAIDs: first‑line for mild‑moderate pain, fewer side effects. Opioids: required for severe pain, delivered IV continuously. --- ⚠️ Common Misunderstandings “Amylase alone diagnoses pancreatitis.” – Amylase can be normal in chronic disease; need lipase or imaging. “All pancreatitis patients need antibiotics." – Only give for proven infection or infected necrosis. “Saline is the only fluid option.” – Lactated Ringer’s is preferred for its more physiologic electrolyte profile. “Cholecystectomy can wait months after an episode.” – Early cholecystectomy (same admission) reduces recurrence. --- 🧠 Mental Models / Intuition “Three‑step diagnosis” → Lab (3× ULN), Image (pancreatic changes), Clinical (typical pain). “Fluid first, then feed” – Think of the pancreas like a fire: cool it down with fluids before adding fuel (nutrition). BISAP = “5‑point danger checklist” – each point adds a layer of risk; ≥2 points = call for higher‑level care. --- 🚩 Exceptions & Edge Cases Chronic pancreatitis may have normal amylase & lipase despite active disease. Hypertriglyceridemia‑induced pancreatitis can cause falsely low serum lipase due to assay interference. Autoimmune pancreatitis: may have normal enzymes; diagnosis relies on IgG4, imaging, and response to steroids. --- 📍 When to Use Which Choose imaging: Suspected gallstones: start with ultrasound. Assess necrosis or severe disease: order contrast CT after 48 h. Evaluate ductal anatomy or unclear diagnosis: use MRI/MRCP or EUS. Pain regimen: Mild‑moderate pain: give NSAID first. Severe pain or NSAID contraindication: start IV opioid infusion. Nutritional route: Patient tolerates oral intake: early oral feeding. Unable to tolerate: place NG/NJ tube for enteral nutrition within 48 h. Antibiotics: give only if imaging/clinical signs show infected necrosis or cholangitis. --- 👀 Patterns to Recognize Upper‑abdominal burning pain → radiates to back = classic pancreatitis presentation. Elevated lipase ≥ 3× ULN + gallstones on US = high suspicion for gallstone pancreatitis. BISAP ≥2 + pleural effusion = likely severe disease → consider ICU. Steatorrhea + weight loss + normal enzymes → think chronic exocrine insufficiency. --- 🗂️ Exam Traps “Serum amylase > lipase is diagnostic.” – Lipase is more specific; amylase may be normal in chronic cases. “All patients need prophylactic antibiotics.” – Only for documented infection; prophylaxis is NOT recommended. “CT should be done immediately on presentation.” – Early CT may miss necrosis; optimal after 48 h. “Gallstone pancreatitis can be managed without cholecystectomy.” – Delaying cholecystectomy increases recurrence risk; early removal is advised. “Any fluid resuscitation works.” – Moderate‑aggressive lactated Ringer’s is the evidence‑based choice; overly aggressive fluids can cause pulmonary edema.