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PTD - 168

Test Directory -  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.
Macroaylase 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 

Combined Pathology Blood form (Yellow/Black or Blue for GP's)

Availability

Referred test: Analysed at Biochemsitry, Southend Hospital

Specific Criteria  

See rejection criteria

  Patient Preparation   None required

Turnaround Time

Two days (Monday to Friday)

Specimen

Serum

Volume

2 ml

Container


Yellow top (SST) tube

Paediatric orange top (lithium-heparin)

Causes for Rejection

Unlabelled sample, normal amylase

Reference Range

Present or not present in significant amounts

Interpretation

 

For samples where significant amounts of macroamylase are present an interpretative comment will be added to indicate clinical significance.

Lab. Handling

Processing: Aliquot and store at 4C in separating fridge (CB39).

Referral:  SASOD and send or BPRO and save in separating freezer (CB40) at -20C, saved frozen rack.


Version 1.0 / April 2014                                                                                                          Approved by: Consultant Biochemist