Bonus online case: Cannabis-induced acute pancreatitis

This patient had been admitted repeatedly with symptoms of pancreatitis.


The patient

A 41-year-old man with type 2 diabetes, prior cholecystectomy, active marijuana use, and recurrent pancreatitis presented with severe, intermittent epigastric pain for two days. The pain was sudden in onset, radiating to the back, and associated with nausea and four episodes of non-bilious, non-bloody vomiting. He reported no fever, chills, correlation of pain with food intake, or history of alcohol use. This was his fourth such episode in eight months; the initial episode was considered secondary to alogliptin, which was discontinued.

A workup including abdominal ultrasound, blood alcohol level, lipid profile, immunoglobulin G panel, and infectious disease testing (hepatitis A, B, and C) was negative. His vital signs were normal. On examination, his abdomen was tender to palpation in the epigastrium, but the remainder of his physical exam was unremarkable.

Labs were significant for an elevated amylase level of 157 U/L (reference range, <100 U/L) and an elevated lipase level of 456 U/L (reference range, <60 U/L). Ultrasound of the abdomen showed an absent gallbladder and no biliary ductal dilatation. The CTs of the abdomen and pelvis that had been performed during three prior admissions were negative for any evidence of pancreatitis, peripancreatic fluid, or biliary duct dilatation. A urine toxicology screen was positive for tetrahydrocannabinol on this and prior admissions.

The patient's symptoms resolved with conservative management, and he was discharged after extensive counseling to encourage cannabis cessation. He presented to the gastroenterology clinic three months after discharge and reported being symptom-free after marijuana cessation.

The diagnosis

This patient was diagnosed with recurrent acute pancreatitis due to cannabis use. Cannabis was first documented as a cause of acute pancreatitis in 2004, and there have been at least 26 reported cases. Cannabis-related acute pancreatitis is idiopathic. It occurs primarily in patients younger than age 35 years who present without evidence of a common cause of pancreatitis. About 10% to 15% of patients will have a negative workup (including history, laboratory tests, and imaging results) for these causes. Investigation for less common causes, including medications (sulfonamides, diuretics, didanosine, pentamidine, azathioprine), hypercalcemia, viruses (mumps, hepatitis B, HIV, herpes simplex virus), bacteria (Mycoplasma, Salmonella, Legionella), parasites (Toxoplasma, Cryptosporidium), genetic variations, vasculitis, and toxins (including marijuana) is appropriate.

With the progressive legalization of medical and recreational marijuana, it is important to consider cannabis-induced acute pancreatitis as a differential diagnosis in patients presenting with epigastric pain and elevated lipase. A history focused on marijuana use and urine toxicology screen may aid diagnosis. Although radiological evidence of acute pancreatitis may be helpful, it has not been seen in most of the reported cases. While the pathophysiology of the disease process is not yet proven, one possible mechanism is through agonistic effect of tetrahydrocannabinol on cannabinoid 1 (CB-1) and cannabinoid 2 (CB-2) receptors, both of which are found in the pancreas.

Pearls

  • Cannabis should be considered as a cause of acute pancreatitis when more common causes are not found.
  • A detailed history of cannabis use and a toxicology screen should be considered in all patients with idiopathic acute pancreatitis.

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