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Amylase 

  • Author: Sridevi Devaraj, PhD, DABCC, FACB; Chief Editor: Eric B Staros, MD  more...
 
Updated: Dec 10, 2014
 

Reference Range

The reference range for amylase is as follows:

  • Serum test: Normal is 40-140 U/L
  • Urine Test: Normal is 24-400 U/L
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Interpretation

Conditions associated with high amylase levels are as follows:[1]

  • Intestinal obstruction
  • Pancreatic duct obstruction
  • Cancer
  • Gallbladder attacks
  • Mesenteric thrombosis
  • Postoperative abdominal surgery
  • Macroamylasemia
  • Tubal pregnancy

Conditions associated with low amylase levels are as follows:

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Collection and Panels

The 2 tests for amylase are serum and urine. For both tests, patient should not drink alcohol for 24 hours before the test.

For the blood test, patients should not eat or drink anything except water for 2 hours before the test.

For the urine test, patients should drink enough fluids during the 24-hour test to avoid dehydration. In this test, patients should check with their physician about any medications being taken. Timed urine specimens can be obtained for urinary amylase and normalized to creatinine content.

Methods

Blood is collected into a vacuum tube via venipuncture. For urine, a patient urinates into a small container and then transfers the sample to a lab-provided larger container with a small amount of preservative. Plasma samples that have been anticoagulated with citrate or oxalate should be avoided because amylase is a calcium-containing enzyme and false low levels can be obtained with such specimens.

Notes regarding these methods are as follows:

  • Keep container refrigerated.
  • Do not touch inside of container or drop any foreign matter into it.

Panels

Related tests are as follows:

  • Lipase test
  • Urinalysis
  • Urine creatinine/clearance
  • Isoamylase fractionation
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Background

Description

Amylases are enzymes that catalyze the hydrolysis of amylopectin, amylose, glycogen, and their hydrolyzed products into simple and easily digestible sugars. Amylase is an enzyme produced in the pancreas and by the salivary glands that converts starches, glycogens, and related polysaccharides into simple and easily digested sugar. It is also present in molds, bacteria, yeasts, and plants.

An image depicting an amylase molecule can be seen below.

Amylase molecule from human saliva. The calcium io Amylase molecule from human saliva. The calcium ion is visible and is colored tan; the chloride ion is colored green.

Alpha amylase is of salivary or pancreatic origin and referred to as S-type or P-type amylase, respectively. Pancreatic amylase is secreted by acinar cells of the pancreas and is tissue specific and more temperature labile than salivary amylase. Salivary amylase is synthesized by parotid, sweat, and lactating mammary glands.[2, 3, 4, 5]

On agarose gel, the mobility of the less anionic isoenzyme corresponds to pancreatic amylase, while the more anionic band is salivary amylase. Macroamylasemia is a condition of persistently elevated serum amylase activity with no apparent pancreatic disorder due to the formation of a large amylase-globulin complex, which is not excreted.[6]

Indications/Applications

Most elevations in serum amylase are due to increased rates of amylase entry into the blood stream, decreased rates of clearance or both. The test is primarily used, in conjunction with a lipase test, to help diagnose and monitor acute pancreatitis and other pancreatic disorders. Serum amylase increases in 6-48 hrs of onset of acute pancreatitis but not in proportion to the severity of the disease and activity returns to normal in 3-5 days. Urine amylase increases in proportion to serum amylase and remains elevated for several days after serum amylase has been normalized. The ratio of amylase urinary clearance to creatinine clearance can be used in the diagnosis of acute and relapsing pancreatitis.

Serum amylase levels can also be elevated in pancreatic cancers, although a bit too late to be diagnostically useful; however, the results can assist in monitoring treatment of pancreatic cancers. Other conditions in which determination of serum amylase is useful is to determine the effects of the removal of gallstones, and swelling and inflammation of the salivary/parotid glands.

Indications for testing are as follows:[7]

  • Severe abdominal pain
  • Fever
  • Loss of appetite
  • Nausea
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Contributor Information and Disclosures
Author

Sridevi Devaraj, PhD, DABCC, FACB Medical Director of Clinical Chemistry and POCT, Texas Children's Hospital; Professor of Pathology and Immunology, Baylor College of Medicine; Associate Director of Translation, Texas Children's Microbiome Center

Disclosure: Nothing to disclose.

Chief Editor

Eric B Staros, MD Associate Professor of Pathology, St Louis University School of Medicine; Director of Clinical Laboratories, Director of Cytopathology, Department of Pathology, St Louis University Hospital

Eric B Staros, MD is a member of the following medical societies: American Medical Association, American Society for Clinical Pathology, College of American Pathologists, Association for Molecular Pathology

Disclosure: Nothing to disclose.

References
  1. WebMD.com.

  2. Koh D, Ng V, Naing L. Alpha amylase as a salivary biomarker of acute stress of venepuncture from periodic medical examinations. Front Public Health. 2014. 2:121. [Medline]. [Full Text].

  3. Noorani H, Joshi HV, Shivaprakash P. Salivary Alpha Amylase as a Noninvasive Biomarker for Dental Fear and Its Correlation with Behavior of Children during Dental Treatment. Int J Clin Pediatr Dent. 2014 Jan. 7(1):19-23. [Medline]. [Full Text].

  4. Geron E, Schejter ED, Shilo BZ. Assessing the secretory capacity of pancreatic acinar cells. J Vis Exp. 2014 Aug 28. [Medline].

  5. Filaire E, Massart A, Hua J, Le Scanff C. Dietary Intake, Eating Behaviors, and Diurnal Patterns of Salivary Cortisol and Alpha-Amylase Secretion Among Professional Young Adult Female Tennis Players. Int J Sport Nutr Exerc Metab. 2014 Sep 8. [Medline].

  6. Fischbach FT, Dunning MB III, eds. Manual of Laboratory and Diagnostic Tests. 8th ed. Philadelphia: Lippincott Williams and Wilkins; 2009.

  7. Henry JB. Clinical Diagnosis and Management by Laboratory Methods.

  8. aids.org.

  9. Kjaergaard AD, Bojesen SE, Nordestgaard BG, Johansen JS. YKL-40 and Alcoholic Liver and Pancreas Damage and Disease in 86 258 Individuals from the General Population: Cohort and Mendelian Randomization Studies. Clin Chem. 2014 Sep 15. [Medline].

  10. www.globalrph.com.

  11. www.medterms.com.

 
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Amylase molecule from human saliva. The calcium ion is visible and is colored tan; the chloride ion is colored green.
 
 
 
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