View source for Lipase

==Background==
*Lipase is a pancreatic enzyme that hydrolyzes triglycerides into glycerol and free fatty acids.
*Serum lipase is the preferred biomarker for the diagnosis of [[Pancreatitis|acute pancreatitis]] in the emergency department, offering superior sensitivity and a wider diagnostic window compared to [[amylase]].<ref>Cartier T, Sogni P, Perruche F, et al.
*Normal lipase serum level in acute pancreatitis: is it an early or late determination? ''Emerg Med J''. 2011;28(11):997-998.</ref>


* Lipase is primarily produced by pancreatic acinar cells; smaller amounts are produced by the liver, intestinal mucosa, and other tissues
* Normal reference range is approximately 0-160 U/L (varies by assay and institution)
* Preferred over [[amylase]] for diagnosis of [[Pancreatitis|acute pancreatitis]] per ACG, AGA, and IAP guidelines<ref>Tenner S, Baillie J, DeWitt J, Vege SS; American College of Gastroenterology. American College of Gastroenterology guideline: management of acute pancreatitis. ''Am J Gastroenterol''. 2013;108(9):1400-1415.</ref>

==Diagnostic threshold==
* ≥3 times the upper limit of normal (ULN) is the accepted diagnostic cutoff for [[Pancreatitis|acute pancreatitis]]
** At this threshold: sensitivity 80-100%, specificity 95-99%<ref>Sternby B, O'Brien JF, Zinsmeister AR, DiMagno EP. What is the best biochemical test to diagnose acute pancreatitis? A prospective clinical study. ''Mayo Clin Proc''. 1996;71(12):1138-1144.</ref>
* Rises within 3-6 hours of symptom onset
* Peaks at 24-48 hours
* Remains elevated for 7-14 days (longer than amylase, which normalizes within 3-5 days)
* A normal lipase does not completely exclude acute pancreatitis, particularly in recurrent or chronic disease

==Interpretation==

===Lipase ≥3x ULN===
* Highly suggestive of [[Pancreatitis|acute pancreatitis]] when combined with compatible clinical presentation
* Diagnosis of acute pancreatitis requires ≥2 of 3 criteria:<ref>Banks PA, Bollen TL, Dervenis C, et al. Classification of acute pancreatitis — 2012: revision of the Atlanta classification and definitions by international consensus. ''Gut''. 2013;62(1):102-111.</ref>
** Characteristic abdominal pain (epigastric, radiating to back)
** Serum lipase (or amylase) ≥3x ULN
** Characteristic findings on imaging (CT, MRI, or ultrasound)

===Lipase <3x ULN but elevated===
* Non-specific; consider both pancreatic and non-pancreatic causes
* Abdominal imaging advised if associated with abdominal pain

===Non-pancreatic causes of elevated lipase===
* Reduced clearance:
** [[Renal failure]] / [[Acute kidney injury|AKI]] (most common non-pancreatic cause; incidence 14-80% in renal failure)<ref>Manjuck J, Zein J, Ghai V, et al. Nonpancreatic causes of significantly elevated serum lipase in the ICU: a systematic review. ''HPB''. 2015;17(3):195-199.</ref>
** Macrolipasemia (lipase-immunoglobulin complexes)
* Intra-abdominal pathology:
** [[Cholecystitis]], [[choledocholithiasis]]
** [[Small bowel obstruction]]
** [[Mesenteric ischemia]] / intestinal infarction
** [[Peptic ulcer disease]] / [[Perforated viscus|perforated viscus]]
** [[Appendicitis]]
** [[Inflammatory bowel disease]]
** Pancreatic or periampullary malignancy
* Metabolic:
** [[Diabetic ketoacidosis]] (may elevate lipase >3x ULN without pancreatitis)
** [[Hypertriglyceridemia]]
* Other:
** [[Sepsis]] / critical illness
** Intracranial hemorrhage / neurosurgical pathology
** Medications (e.g., DPP-4 inhibitors, valproic acid, azathioprine, didanosine)
** Post-[[ERCP]]
** [[Trauma]]
** HIV infection

==Pearls==
* Lipase alone is sufficient — co-ordering amylase with lipase does not improve diagnostic accuracy and adds unnecessary cost<ref>Moridani MY, Bromberg IL. Lipase and pancreatic amylase versus total amylase as biomarkers of pancreatitis: an analytical investigation. ''Clin Biochem''. 2003;36(1):31-33.</ref>
* '''Do not trend lipase''' — serial monitoring is unnecessary and does not predict severity, complications, or guide management<ref>Tenner S, Baillie J, DeWitt J, Vege SS. American College of Gastroenterology guideline: management of acute pancreatitis. ''Am J Gastroenterol''. 2013;108(9):1400-1415.</ref>
* Degree of lipase elevation does '''not''' correlate with disease severity in adults
* Lipase has a wider diagnostic window than amylase, making it more useful in patients with '''delayed presentations''' (>24-48 hours after symptom onset)
* In [[Hypertriglyceridemia|hypertriglyceridemic pancreatitis]], lipase may be falsely normal due to assay interference; if clinical suspicion is high, treat empirically
* Consider '''non-pancreatic causes''' when lipase is elevated but clinical features are not consistent with pancreatitis, especially in patients with [[Renal failure|renal failure]] or [[Diabetic ketoacidosis|DKA]]
* If the diagnosis remains uncertain, CT abdomen with IV contrast is recommended '''≥72 hours''' after symptom onset for optimal sensitivity in detecting necrosis

==See Also==
* [[Pancreatitis]]
* [[Amylase]]
* [[Choledocholithiasis]]
* [[Diabetic ketoacidosis]]
* [[Hypertriglyceridemia]]
* [[ERCP]]

==External Links==
* [https://gi.org/guideline/acute-pancreatitis/ ACG Clinical Guideline: Acute Pancreatitis]

==References==
<references/>

[[Category:Pharmacology]]
[[Category:GI]]
[[Category:Labs]]