What Causes Elevated Amylase?

Patient Presentation
A pediatrician received a “curb-side” telephone consultation from a psychiatrist regarding
a 14-year-old female was admitted for treatment of a mixed anorexia/bulimia eating disorder.
She was medically stable and only complained of some minor upper abdominal pain after eating. She also had normal bowel and bladder habits.
Her laboratory evaluation was generally unremarkable except for hyperamylasemia that was trending downward.
Now it was increasing from 264 U/L two weeks previously to 305 U/L. Fractionation showed 75% was pancreatic, and the psychiatrist wondered what should be done.
The diagnosis of hyperamylasemia was made but the pediatrician wasn’t sure what to recommend.
So he said he would look up an answer and call back.
In searching PUBMED he found an abstract that briefly discussed the normal production, circulation and metabolism of amylase.
The pediatrician thought that maybe she was having some gastritis that was causing bowel irritation or bowel irritation itself that could cause increased reabsorption of the amylase, but recommended to check trypsinogen and lipase as other markers of potential acute pancreatitis and to also check blood urea nitrogen and creatinine to check for renal clearance.
He also recommended if any of these were abnormal to then consult with a gastroenterologist.
The pediatrician later learned that she did have some minor elevation of trypsinogen and lipase with normal renal function tests, but one week later these had normalized and her amylase was now down to 240 U/L. The actual cause continued to be unknown.


The eating disorders bulimia and anorexia can occur together and their general features are listed below.
Patients with anorexia nervosa refuse to maintain their body weight at or above a minimally normal weight for age and height (basically less than 85% of expected).
They have an intense fear of gaining weight or becoming fat, even though they are underweight.
They also have a distorted view of their own body weight or shape and often deny the seriousness of being underweight.
For women who are postmenarchal, amenorrhea often occurs.

Patients with bulimia nervosa have recurrent episodes of binge eating. A binge episode is eating an amount of food that is larger than most people would eat during a similar amount of time or similar circumstances. Patients eat this over a discrete time period (i.e. 2 hours)
During the episodes the patient feels a lack of control over the eating.
Patients have recurrent behaviors to prevent weight gain from the overeating episodes (i.e. fasting, excessive exercise, self-induced vomiting, using laxatives, diuretics, or enemas).
The overeating and inappropriate compensatory behaviors both occur at least twice a week for 3 months when averaged.
Patients have a distorted image of their weight and body shape.

Hyperamylasemia is common in patients with bulimia because recurrent emesis causes increased salivary production of amylase. Fractionated amylase in bulimics usually shows elevated salivary amylase and not elevated pancreatic amylase as in the patient above.

Learning Point
Amylase concentration in the serum is the product of the production and entry into the blood versus the removal from the blood.
Amylase fractionation can be helpful in determining the potential source since most of the amylase comes from the pancreas or salivary glands.
Amylase can also be produced by other organs including the fallopian tube, lung, thyroid and tonsils in addition to malignant neoplasms.
Pancreatic amylase in the gastrointestinal tract tightly binds to the small bowel mucosa and therefore small bowel injury can cause an elevation in serum amylase.
Maltase may also cross-react with amylase in some laboratory assays.

Clearance of serum amylase is renal therefore renal failure is also a cause of hyperamylasemia.
An amylase variation where the molecule is very large (i.e. macroamylasemia) also causes hyperamylasemia due to decreased clearance.

The differential diagnosis of hyperamylasemia includes:

  • Pancreatic – pancreatitis, instrumentation, pseudocyst, trauma, choledocholithiasis, cystic fibrosis, biliary sludge, cancer
  • Salivary – parotitis, calculi, trauma, surgery
  • Bowel – trauma, perforation, infarct, obstruction, peritonitis, appendicitis
  • Liver – hepatitis, cirrhosis
  • Genitourinary – fallopian or ovarian cysts, salpingitis, ruptured ectopic pregnancy
  • Renal – renal failure
  • Other
    • Acidosis – ketoacidosis or non-ketotic acidosis
    • Abdominal aortic aneurism
    • Alcoholism
    • Drugs
    • Eating disorders – anorexia nervosa, bulimia
    • Extracorporal circulation
    • Macroamylasemia
    • Pneumonia
    • Trauma – cerebral, burns

Questions for Further Discussion
1. What are the physiological effects of anorexia or bulimia?
2. What laboratory abnormalities are seen in anorexia or bulimia?
3. How often do eating disorder cause death?
4. How is acute pancreatitis treated?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at the National Guideline Clearinghouse and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for this topic: Eating Disorders and at Pediatric Common Questions, Quick Answers for this topic: Eating Disorders

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

Pieper-Bigelow C, Strocchi A, Levitt MD. Where does serum amylase come from and where does it go? Gastroenterol Clin North Am. 1990 Dec;19(4):793-8.

Bakerman S, Bakerman P, Strausbauch P. Bakerman’s ABC’s of Interpretive Laboratory Data. 4th edit. Interpretive Laboratory Data, Inc. Scottsdale, AZ. 2002;47-49.

Behavenet. Anorexia nervosa.
Available from the Internet at http://www.behavenet.com/capsules/disorders/anorexia.htm (rev. 2008, cited 10/1/08).

Behavenet. Bulimia Nervosa.
Available from the Internet at http://www.behavenet.com/capsules/disorders/bulimia.htm (rev. 2008, cited 10/1/08).

ACGME Competencies Highlighted by Case

  • Patient Care

    2. Essential and accurate information about the patients’ is gathered.
    3. Informed decisions about diagnostic and therapeutic interventions based on patient information and preferences, up-to-date scientific evidence, and clinical judgment is made.
    6. Information technology to support patient care decisions and patient education is used.

    8. Health care services aimed at preventing health problems or maintaining health are provided.
    9. Patient-focused care is provided by working with health care professionals, including those from other disciplines.

  • Medical Knowledge
    10. An investigatory and analytic thinking approach to the clinical situation is demonstrated.
    11. Basic and clinically supportive sciences appropriate to their discipline are known and applied.

  • Practice Based Learning and Improvement
    12. Evidence from scientific studies related to the patients’ health problems is located, appraised and assimilated.
    13. Information about other populations of patients, especially the larger population from which this patient is drawn, is obtained and used.
    15. Information technology to manage information, access on-line medical information and support the healthcare professional’s own education is used.
    16. Learning of students and other health care professionals is facilitated.

  • Professionalism
    20. Respect, compassion, and integrity; a responsiveness to the needs of patients and society that supercedes self-interest; accountability to patients, society, and the profession; and a commitment to excellence and on-going professional development are demonstrated.

  • Systems Based Practice
    23. Differing types of medical practice and delivery systems including methods of controlling health care costs and allocating resources are known.
    24. Cost-effective health care and resource allocation that does not compromise quality of care is practiced.
    26. Partnering with health care managers and health care providers to assess, coordinate, and improve health care and how these activities can affect system performance are known.

    Donna M. D’Alessandro, MD
    Professor of Pediatrics, University of Iowa Children’s Hospital

    November 10, 2008