What it is:Two different diseases sharing one organ. Acute pancreatitis (AP)is a sudden inflammatory attack where the pancreas starts digesting itself. Chronic pancreatitis (CP)is decades of low-grade injury that permanently scars the gland and kills off both its digestive and hormonal function.
The core problem:In AP, trypsinogen gets activated to trypsin inside the pancreas instead of the duodenum. That one wrong switch triggers a cascade of self-digesting enzymes, cytokine release, and a systemic inflammatory response that can spiral into organ failure. In CP, that same recurring injury over years leaves fibrosis instead of functioning tissue, so the gland stops making enough enzymes (malabsorption) and eventually stops making enough insulin (diabetes).
What you do about it:AP is supportive care while the storm passes: fluids, pain control, nutrition, and antibiotics only if there's an actual infection. CP is about replacing what the gland can no longer do: enzymes for digestion, a structured pain ladder, and insulin when the endocrine tissue burns out too.
Think of it as autodigestion, acute vs. chronic.AP is the pancreas eating itself in real time (you're resuscitating through an event). CP is the pancreas having already eaten most of itself over years (you're replacing lost function). Same starting mechanism (premature enzyme activation), completely different management mindset.
Once AP is diagnosed, the very next question is how sick this patient actually is, because that decides whether they go home, go to the floor, or go to the ICU. The guideline algorithm sorts patients into three tiers based on how they're trending, not just how they look on arrival.
Pain and labs trending down early.
May develop systemic complications.
Organ dysfunction or necrosis risk.
Every AP patient gets the same starting bundle regardless of tier: screen for SIRS, start goal-directed fluid management, correct electrolytes, treat metabolic abnormalities, control pain, and check whether a medication could be the culprit. Consider ERCP specifically if there's cholangitis or biliary pancreatitis with a common bile duct obstruction.
AP and CP are not points on the same spectrum you just wait out.Most AP resolves completely. CP is progressive and largely irreversible. A patient can have repeated bouts of AP (especially alcohol-related) that eventually tip into CP, but you should never counsel a CP diagnosis as "bad pancreatitis" the way you would a severe AP episode.
Gallstones and alcohol account for most US cases. Diabetes and autoimmune disease (like IBD) also raise risk, and a meaningful chunk of cases are idiopathic. Drug-induced AP is real but rare, and it's genuinely hard to prove causation since you can't ethically rechallenge a patient to confirm it.
The trigger is premature activation of trypsinogen to trypsin inside the pancreasinstead of the duodenum where it belongs. Trypsin then activates a cascade of other digestive enzymes, and the gland starts digesting its own tissue. Lipase specifically damages fat cells, and the toxic byproducts of that fat necrosis injure surrounding pancreatic and peripancreatic tissue further.
Injured acinar cells release cytokines and chemoattractants that pull in neutrophils and macrophages, amplifying inflammation into full systemic inflammatory response syndrome (SIRS). Vascular damage and ischemia release kinins, which make capillary walls leaky and drive tissue edema. Increased intestinal permeability lets colonic bacteria translocate into the inflamed pancreas, which is how sterile necrosis becomes an infected one.
Every AP treatment target traces back to this cascade. Fluidsfight the capillary leak and hypovolemia from kinin-driven permeability. Nutrition supportcounters the catabolic state from systemic inflammation. Antibioticsonly make sense once you understand bacterial translocation is what turns necrosis infected, which is exactly why they're not given prophylactically.
CP is what's left after long-standing, often repeated pancreatic inflammation: irreversible destruction of pancreatic tissue with fibrin deposition and progressive loss of both exocrine (enzyme) and endocrine (insulin) function. Chronic alcohol use causes roughly two-thirds of Western cases; most of the rest are idiopathic, with a small slice from rarer causes like autoimmune, hereditary, or tropical pancreatitis.
The exact trigger mechanism isn't fully mapped, but activation of pancreatic stellate cellsby toxins, oxidative stress, and inflammatory mediators appears to drive the fibrin deposition that replaces working tissue.
CP pain is not just "the pancreas is inflamed right now." Abnormal central pain processing and sensitized visceral nerves develop over time, producing hyperalgesiaand impaired inhibition of pain pathways. That's why some CP patients report pain in areas distant from the pancreas, and why pain can persist even when imaging looks quiet. It's also why the pain ladder for CP leans on neuropathic adjuvants like pregabalin, not just stronger opioids.
Presentation ranges from moderate discomfort to shock and respiratory distress, depending on how much local and systemic damage has occurred. Abdominal pain hits 95% of patients, classically epigastric, radiating to the upper quadrants or back, sudden in onset, and described as "knife-like" or "boring." It usually peaks within 30 minutes and can persist for hours to days. Nausea and vomiting occur in 85%, typically after the pain starts.
| Category | Findings |
|---|---|
| Abdominal exam | Marked epigastric tenderness, rebound tenderness and guarding in severe cases, distended and tympanic abdomen, decreased or absent bowel sounds when severe |
| Vitals | Can be normal, but hypotension, tachycardia, and low-grade fever are common, especially with widespread inflammation/necrosis |
| Respiratory | Dyspnea and tachypnea signal acute respiratory complications |
| Other | Jaundice and altered mental status can appear; other signs of alcoholic liver disease may be present in alcoholic pancreatitis |
Pancreatitis pain is classically worse lying supine or walking, and better leaning forward or sitting up. That positional pattern, plus knife-like epigastric pain radiating straight to the back, is a strong bedside clue before labs even come back.
Pancreatitis pain typically localizes to the left upper quadrant or periumbilical region, which overlaps with the differential for gastritis, GERD, and abdominal aortic aneurysm (periumbilical) or splenic pathology (LUQ). Right upper quadrant pain with fever and a positive Murphy's sign(pain on deep inspiration while palpating under the right costal margin) points you toward biliary disease instead, which matters because gallstones can cause pancreatitis, so the two aren't mutually exclusive on your differential.
The core features are abdominal pain, malabsorption with steatorrhea, weight loss, and diabetes.Jaundice shows up in roughly 10% of patients. Pain is typically deep and penetrating, epigastric or diffusely abdominal, radiating to the back, and often worse with meals and at night, sometimes with nausea and vomiting. Steatorrhea and azotorrhea occur in most patients, frequently with diarrhea and bloating, and weight loss follows. Pancreatic diabetes is a late finding, commonly associated with visible pancreatic calcification on imaging.
AP diagnosis requires 2 of these 3: (1) upper abdominal pain, (2) serum lipase or amylase ≥3× the upper limit of normal, and (3) characteristic imaging findings. You do not need all three.
Transabdominal ultrasoundshould be done in everyone to look for dilated biliary ducts and gallstones. Contrast-enhanced CT (CECT)is used when the diagnosis isn't clear from clinical and lab findings alone. MRIis reserved for grading severity, finding bile duct problems CECT missed, or when CECT is contraindicated.
| Rises | Peaks | Normalizes | Notes | |
|---|---|---|---|---|
| Amylase | 4–8 h after onset | ~24 h | 8–14 days | Less specific to the pancreas |
| Lipase | Parallels amylase | Parallels amylase | Persists longer | Specific to the pancreas; still elevated after amylase normalizes |
Diagnosis leans on clinical presentation plus imaging or pancreatic function testing, since amylase and lipase are usually normal or only mildly elevatedin CP (they can bump up during an acute exacerbation). Total bilirubin, alkaline phosphatase, and transaminases may rise with ductal obstruction; albumin and calcium may be low from malnutrition.
| Test | Abnormal cutoff / what it measures |
|---|---|
| Serum trypsinogen | <20 ng/mL |
| Fecal elastase | <200 mcg/g stool |
| Fecal chymotrypsin | <3 units/g stool |
| Fecal fat estimation | >7 g/day (needs a 72-hour stool collection) |
| ¹³C-mixed triglyceride breath test | Not available in the US |
| Secretin stimulation | Evaluates duodenal bicarbonate secretion |
| Cholecystokinin (CCK) stimulation | Evaluates pancreatic lipase secretion |
Imaging ranges from noninvasive (abdominal ultrasound, CT, MRI) to invasive (endoscopic ultrasonography, ERCP).
Goals:relieve pain and nausea, replace fluids, correct electrolyte/glucose/lipid abnormalities, minimize systemic complications, and manage necrosis or infection if they occur.
Prophylactic antibiotics are NOT recommended in AP without signs or symptoms of infection, even in patients predicted to develop severe AP or necrotizing pancreatitis. This is one of the most commonly tested points in the chapter because it goes against the instinct to "cover" a sick-looking patient.
| Therapy | Dose | Role |
|---|---|---|
| IV Fluids (goal-directed) | ||
| Lactated Ringer's | 5–10 mL/kg/h or250–500 mL/h for the first 12–24 h | reduces SIRS/organ failure risk |
| Analgesia | ||
| Morphine (parenteral) | Titrated IV; consider PCA if dosing needed q2–3h | symptom control |
| NSAIDs | If not contraindicated | mild-moderate pain |
| Antibiotics (infected AP only) | ||
| Imipenem-cilastatin | 500 mg IV q8h | Historically widely used |
| Meropenem | Formulary-preferred alternative | Newer carbapenem, replacing imipenem on many formularies |
| Ciprofloxacin or levofloxacin + metronidazole | Standard doses | Penicillin-allergic patients |
Vasodilation from the inflammatory response, ongoing vomiting, and NG suction all drive hypovolemia and electrolyte derangement in AP, so fluid replacement isn't optional supportive care, it's core therapy aimed directly at reducing persistent SIRS and organ failure. Lactated Ringer's at 5–10 mL/kg/h or 250–500 mL/hfor the first 12–24 hours is the guideline target.
You're not just running fluids and walking away. Goals for fluid therapyinclude one or more of: heart rate <120 bpm, mean arterial pressure 65–85 mmHg, urine output >0.5–1 mL/kg/h, or hematocrit 35–44% (with transfusion if needed to hit that range).
Parenteral opioids, usually morphine, are the default for AP pain despite the handbook explicitly noting that high-quality supporting evidence is lacking. If a patient needs dosing as frequently as every 2–3 hours, patient-controlled analgesia should be considered so they aren't waiting on nursing for each dose.
NSAIDs may be sufficientfor mild-to-moderate pain if there's no contraindication. In a patient who's volume-depleted or has early renal dysfunction from AP itself, that contraindication question is worth asking explicitly before reaching for an NSAID.
Patients with known or suspected infected APneed broad-spectrum coverage against enteric aerobic gram-negative bacilli and anaerobes, since infection here comes from bacterial translocation across an inflamed, more permeable gut wall. Imipenem-cilastatin (500 mg IV q8h)has historically been the workhorse, though many formularies have shifted to meropenem. For penicillin-allergic patients, a fluoroquinolone (ciprofloxacin or levofloxacin) plus metronidazolecovers the same spectrum.
Outside of confirmed or strongly suspected infection, antibiotics add nothing, including in patients predicted to trend toward severe or necrotizing disease. Resist the urge to "cover" a sick-looking AP patient empirically.
Drug-induced AP is rare and hard to prove causally, but a long list of medications carries some association. Here's a condensed, high-yield version grouped by strength of evidence:
| Well-supported association | Probable association | Possible association (selected) |
|---|---|---|
| 5-aminosalicylic acid, azathioprine, mercaptopurine, sulfasalazine, sulfamethoxazole/trimethoprim, valproic acid, tetracyclines, corticosteroids, opioids, furosemide, didanosine | Hydrochlorothiazide, itraconazole, interferon alfa-2b, methyldopa | ACE inhibitors (enalapril, lisinopril), statins (atorvastatin, simvastatin, pravastatin), GLP-1 agonists (exenatide, liraglutide), metformin, NSAIDs (ibuprofen, indomethacin, ketorolac), omeprazole, sertraline, clozapine, cyclosporine |
This list matters most for the workup step "assess medications as potential contributing factors" in the treatment algorithm. It's not a reason to withhold these drugs broadly, it's a reason to ask about them when the cause of an AP episode is unclear.
Severe AP is where the autodigestion cascade stops staying contained to the pancreas. The distinction between local and systemic complications is worth keeping straight, since they're monitored and managed differently.
| Local complications | Systemic complications |
|---|---|
| Acute fluid collection, pancreatic necrosis, infection, abscess, pseudocyst formation, pancreatic ascites | Respiratory failure; cardiovascular, renal, metabolic, hemorrhagic, and CNS abnormalities |
The algorithm's branch point: if a patient isn't improving on standard therapy, rule out infected pancreatic necrosis. If infection is confirmed, that's when antibiotics start, and invasive interventions (drainage, debridement) are considered alongside them.
Major goalsfor uncomplicated CP: relieve abdominal pain, treat the complications of malabsorption and glucose intolerance, and improve quality of life. Secondary goals:delay complications, and treat associated problems like depression and malnutrition that come along with chronic disease.
Regimens should be individualized, starting at the lowest effective dose and titrating to the max recommended or tolerated dose beforeadding or switching agents. Schedule analgesics around the clock rather than PRNto maximize efficacy, and consider timing short-acting doses before meals if pain is worse postprandially.
First-line, with or without NSAID
Try before stronger opioids
Best evidence: pregabalin
Reserved for severe/refractory pain
Pregabalin has the best evidenceas an adjuvant for CP pain. SSRIs (paroxetine), SNRIs (duloxetine), and TCAs are options for pain that's difficult to manage, which ties directly back to the central sensitization mechanism in CP, this isn't random polypharmacy, it's targeting the neuropathic component of the pain.
| Therapy | Dose |
|---|---|
| Non-opioid / adjuvant | |
| Acetaminophen | 500–650 mg q4–6h |
| Ibuprofen | 200–400 mg q6–8h initially |
| Tramadol | 50–100 mg q4–6h, max 400 mg/day |
| Pregabalin | 75 mg BID initial, max 300 mg BID |
| Opioids (severe/refractory pain only) | |
| Codeine | 30–60 mg q6h |
| Hydrocodone | 5–10 mg q4–6h |
| Morphine sulfate ER | 30–60 mg q8–12h |
| Oxycodone | 5–10 mg q6h |
| Methadone | 2.5–10 mg q8–12h |
| Hydromorphone | 0.5–1 mg q4–6h |
| Fentanyl patch | 25–100 mcg/h, changed q72h |
Adding pancreatic enzyme supplements for pain controlhas been studied and is not recommendedbased on the evidence. Enzymes have exactly one job in this chapter: fixing malabsorption. Don't conflate the two indications on an exam or in practice.
Most CP patients with malabsorption need pancreatic enzyme supplementation to reach adequate nutrition and cut down steatorrhea. Start at 20,000–50,000 units of lipase with each meal, with half that dose with snacks.If there's no improvement, increase up to a max of 90,000 units per mealbefore moving on. If it's still not enough, add an H2RA or PPIand consider further reducing dietary fat. Products using enteric-coated microspheres are preferred, and patients who need more than one capsule or tablet per meal should spread the dosing throughout the meal rather than taking it all at once. Ideally patients eat 3–5 meals a day to make this dosing pattern work.
| Product family | Lipase range (units) | Formulation |
|---|---|---|
| Creon | 3,000–36,000 | Enteric-coated microspheres |
| Zenpep | 3,000–40,000 | Enteric-coated beads |
| Pertzye | 4,000–16,000 | Enteric-coated microspheres with bicarbonate buffer |
| Pancreaze | 2,600–21,000 | Enteric-coated minitablets/microtablets |
| Ultresa | 4,000–23,000 | Enteric-coated minitablets |
| Viokace | 10,440–20,880 | Tablets (not enteric-coated, needs acid suppression) |
Enzyme adverse effects are generally benign, mostly nausea, diarrhea, and intestinal upset at high doses. The one serious but uncommon exception is fibrosing colonopathy, reported mostly in children with cystic fibrosis on high enzyme doses over prolonged periods, not a typical concern in an adult CP patient on standard dosing.
Fat-soluble vitamin deficiencyis worth screening for in malabsorbing CP patients, with supplementation as needed. For CP-related diabetes, exogenous insulinis the primary treatment. Metformincan be used in early CP and carries the added benefit of lowering pancreatic cancer risk.
| Parameter | When | Watching for |
|---|---|---|
| Pain, fluid/electrolyte status, nutrition | Periodically in mild AP | Trajectory of recovery |
| Vital signs, fluid/electrolyte status | Continuous in severe AP (ICU) | Hemodynamic instability |
| WBC, glucose, LDH, AST, albumin, hematocrit, BUN, SCr, INR | Close monitoring in severe AP | Organ dysfunction, worsening severity |
| Lipase, amylase, bilirubin | Less frequent than the above | Trend, not absolute value |
| Signs of infection | Ongoing, especially if not improving | Infected necrosis requiring antibiotics |
| Continuous hemodynamic / arterial blood gas | Severe AP | Respiratory and cardiovascular complications |
| Parameter | When | Watching for |
|---|---|---|
| Pain severity/frequency | Periodically, standardized scale | Analgesic efficacy, need to step up the ladder |
| Bowel function | Ongoing in opioid users | Constipation; prescribe laxatives PRN or scheduled |
| Body weight, stool frequency/consistency | Periodically in enzyme users | Response to enzyme therapy, ongoing steatorrhea |
| Blood glucose | Ongoing in diabetic CP patients | Glycemic control on insulin or metformin |