Pathology Handbook

Macroamylase

Synonyms

-

Clinical Indications

Macroamylase is a high molecular weight form of amylase. It circulates as a complex with immunoglobulins, usually IgA (70%) or IgG (30%). Due to its size, renal excretion is impaired causing a persistently raised serum amylase. It is a benign finding which is usually chronic, but may be transient

Macroamylase is found in 1% of patients with an amylase in the reference range, 5% of patients with an elevated amylase and 13% of HIV positive patients with an elevated amylase.

It is important to identify macroamylase in order to avoid unnecessary invasive and expensive tests. A persistently raised total amylase should raise the possibility of macroamylaseamia, especially in an asymptomatic patient with negative imaging.

Request Form 

Request on ICE after discussion with laboratory

Availability

On request if patient has had raised amylase on 2 occasions without clear evidence of pancreatitis.  Discuss with laboratory before requesting.

Specimen

Serum in gold-top vacutainer

Volume

2 ml

Container

Vacutainer gold top

Lab Handling

Aliquot and store at 4C

Causes for Rejection

Unlabelled or incorrectly labelled sample; not meeting specific criteria for analysis

Reference Range

Not normally detected