Amylase Optimal Testing Recommendations
Also known as: Amylase Total; α-Amylase
- For diagnosis and management of acute pancreatitis, do not order this test if serum lipase test is available.
- May be considered for the diagnosis and monitoring of chronic pancreatitis and other pancreatic diseases
Guidelines for Test Utilization
What does the test tell me?
This test is a marker for acute pancreatitis. 80% of subjects with acute pancreatitis have increased serum amylase within 24 hours. However, the test is not specific for pancreatitis and may be elevated due to other, non-pancreatic causes (such as acute cholecystitis, inflammatory bowel disease, intestinal obstruction, certain cancers, salivary disease, macroamylasemia, etc.).
When should I order this test?
Consider ordering this test when serum lipase is not available as a stat test and the patient presents with a sudden onset of abdominal pain with nausea and vomiting, fever, hypotension and abdominal distension.
When should I NOT order this test?
Do not order the test if the above clinical symptoms are not present or if serum lipase is available. This test has poor specificity and may be increased due to the non-pancreatic causes listed above.
In cases of suspected acute pancreatitis, consider ordering lipase instead of amylase.
How should I interpret the result?
In acute pancreatitis, a 3-fold increase in serum amylase above the upper reference limit typically occurs with a peak at 3 to 6 hours after onset of symptoms. Elevations may persist 3 to 5 days; amylase has a half-life of 10 to 12 hours. The magnitude of increase is not related to the severity of pancreatic involvement.
Is the test result diagnostic/confirmatory of the condition? If not, is there a diagnostic/confirmatory test?
If amylase is elevated under the clinical circumstances outlined above ("When should I order this test?"), the test may be considered diagnostic for acute pancreatitis. However, lipase is preferred over amylase in cases of acute pancreatitis due to the increased specificity of lipase. See below ("What other test(s) might be indicated?").
Are there factors that can affect the lab result?
- Lipemic sera (hypertriglyceridemia) may contain inhibitors which falsely depress results.
- Oxalate or citrate depresses results.
- Some drugs that may cause amylase to rise include aspirin, diuretics, oral contraceptives, corticosteroids, indomethacin, ethyl alcohol, and opiates (such as codeine and morphine).
- Amylase results may be elevated in patients with macroamylasemia. Macroamylase is a high-molecular-weight form of amylase present in serum, i.e., amylase complexed with immunoglobulin, usually IgA or IgG. The large size of the macroamylase complex prevents its excretion in the urine. As a result, the serum amylase is usually elevated. A finding of persistently increased total amylase unrelated to the pancreas should raise the possibility of macroamlyase. Macroamylase may be distinguished by measurement of urine amylase, which is usually low in patients with macroamylasemia but usually high in patients with acute pancreatitis.
Are there considerations for special populations?
What other test(s) might be indicated?
Lipase is another pancreatic enzyme elevated with amylase in acute pancreatitis, but the elevation of lipase is more prolonged (up to two weeks), giving it a larger diagnostic window than amylase. Lipase elevation is also more specific to pancreatic causes. Current guidelines and recommendations indicate that lipase should be preferred over total amylase for initial diagnosis of acute pancreatitis. Testing both amylase and lipase should be discouraged because it increases costs while only marginally improving diagnostic efficiency compared to lipase alone.
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Barbieri JS, Riggio JM, Jaffe R. Amylase testing for abdominal and suspected Acute Pancratitis. J Hosp Med 2016, 11(5): 366-368.
Basnayake C, Ratnam D. Blood test for acute pancreatitis. Aust Prescr. Aug 2015;38:128-30.
Lippi, G, Valentino, M, Cervellin G. Laboratory diagnosis of acute pancreatitis: in search of the Holy Grail. Crit Rev Clin Lab Sci. Jan – Feb 2012; 49(1)18-21.
Tietz Textbook of Clinical Chemistry & Molecular Diagnostics. Edited by CA Burtis and ER Ashwood & DE Burns. Elsevier, 5th Ed, 2012.
Vissers RJ, McHugh DF. Amylase and Lipase in Emergency Department evaluation of Acute Pancreatitis. Clin Lab Emer Med 1999, 17(6): 1027-1037.
Barbieri JS, Riggio JM, Jaffe R, Amylase Testing for Acute Pancreatitis. J. Hosp. Med 2016;5;366-368. doi:10.1002/jhm.2544.
Last reviewed: June 2020. The content for Optimal Testing: AACC's Guide to Lab Test Utilization has been developed and approved by the AACC Academy and AACC's Science and Practice Core Committee.
As the fields of laboratory medicine and diagnostic testing continue to grow at an incredible rate, the knowledge and expertise of clinical laboratory professionals is essential to ensure that patients received the highest quality and most useful laboratory tests. AACC's Academy and Science and Practice Core Committee have developed a test utilization resource focusing on commonly misused tests in hospitals and clinics. Improper test utilization can result in poor patient outcomes and waste in the healthcare system. This important resource geared toward medical professionals recommends better tests and diagnostic practices. Always consult your laboratory director to make sure these recommendations are appropriate for your patient population.