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 on ICE after discussion with laboratory
On request if patient has had raised amylase on 2 occasions
without clear evidence of pancreatitis. Discuss with
laboratory before requesting.
Serum in gold-top vacutainer
Aliquot and store at 4C
Causes for Rejection
Unlabelled or incorrectly labelled sample; not meeting specific
criteria for analysis
Not normally detected