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Amylase, Total; AMY

Pseudonyms: Alpha Amylase

General information

Collection Container:

Blood

Adults - serum (with gel separator, 4.9mL Starstedt brown top).

Paediatrics - lithium heparin plasma (1.2mL Starstedt orange top tube).

Type and volume of sample: The tubes should be thoroughly mixed before transport to the lab. The test may be added to a profile without provision of a separate specimen provided a full tube has been received.

Urine

A 24h sample should be collected (plain bottle)

Laboratory information

Method Principle: Defined oligosaccharides such as 4,6‑ethylidene‑(G7)‑p‑nitrophenyl‑(G1)‑α,D‑maltoheptaoside (ethylidene‑G7PNP)a) are cleaved under the catalytic action of α‑amylases. The G2PNP, G3PNP and G4PNP fragments so formed are completely hydrolyzed to p‑nitrophenol andglucose by α‑glucosidase.The color intensity of the p‑nitrophenol formed is directly proportional to theα‑amylase activity. It is determined by measuring the increase inabsorbance.

Biological reference ranges:

Blood (all ages): 28-100 IU/L

Urine: Compare with serum levels in demonstrating the presence of macroamylase when urine levels are very low in the presence of raised serum amylase.

Note: The normal distribution in adults is skewed with normal individuals occasionally demonstrating values up to 200 IU/L. This most often occurs in patients of African, Afro-Caribbean or Asian heritage and has been termed 'ethnic hyperamylasaemia'.

Turnaround times: Results available within 1 hour (urgent - for paeds, please phone lab in advance of sampling) or 4 hours (routine).

Clinical information

Amylase has five main isoenzymes but only the pancreatic and salivary isoforms have relevance except in very rare circumstances. In health, [total amylase] in plasma is typically made up of 1/3 pancreatic and 2/3 salivary isoforms.

Pathophysiological elevations are associated with acute pancreatitis, acute-on-chronic pancreatitis, pancreatic pseudocyst, post-ERCP pancreatitis, post cardiopulmonary bypass surgery, acute cholecystitis, renal disease, perforated viscera, Sjogren's syndrome, parotitis and ovarian or lung malignancies. Elevations above 10 times the upper limit of the reference interval are strongly suggestive of acute pancreatitis. Levels of 3 to 10 times the upper limit of the reference interval may be due to pancreatitis in patients with a compatible clinical picture but other non-pancreatic causes must be excluded.

Levels may be strongly elevated in patients undergoing radiotherapy.

Numerous drugs are associated with drug-induced pancreatitis and elevations in plasma amylase activity. Most commonly associated are didanosine, asparaginase, azathioprine, valproic acid, pentavalent antimonials, pentamidine, mercaptopurine, mesalamine, estrogen preparations, opiates, tetracycline, cytarabine, steroids, trimethoprim/sulfamethoxazole, sulfasalazine, furosemide, and sulindac. There are many other drugs where a weaker association is described.

Factors known to significantly affect the results:

  • African, Asian, West Indian or Indian Subcontinent heritage may give rise to values in health up to 2 x ULRR (described in Lancet 1982: Apr 10;1(8276):856).
  • The presence of a macroamylase (enzyme bound to immunoglobulin) may result in a non‐pathological increase in total amylase activity.  If this is suspected, macroamylase can be analysed by a referral lab.
  • Grossly lipaemic samples are unsuitable for analysis

 

(Last reviewed 25th June 2017)


Amylase, Total; AMY
Pseudonyms: Alpha Amylase
General Information:
Collection Container
Blood
Adults - serum (with gel separator, 4.9mL Starstedt brown top).
Paediatrics - lithium heparin plasma (1.2mL Starstedt orange top tube).
Type and volume of sample
The tubes should be thoroughly mixed before transport to the lab. The test may be added to a profile without provision of a separate specimen provided a full tube has been received.
Urine
A 24h sample should be collected (plain bottle)
Specimen transport/Special Precautions. N/A
Laboratory Information:
Method Principle.
Defined oligosaccharides such as 4,6‑ethylidene‑(G7)‑p‑nitrophenyl‑(G1)‑α,D‑maltoheptaoside (ethylidene‑G7PNP)a) are cleavedunder the catalytic action of α‑amylases. The G2PNP, G3PNP and G4PNPfragments so formed are completely hydrolyzed to p‑nitrophenol andglucose by α‑glucosidase.
The color intensity of the p‑nitrophenol formed is directly proportional to theα‑amylase activity. It is determined by measuring the increase inabsorbance.
Biological reference Ranges