Abstract
A macroenzyme -- an enzyme bound to an immunoglobulin or otherwise complexed into a high-molecular-weight form -- clears
from plasma more slowly than the native enzyme, producing a persistently elevated result with no underlying tissue pathology, and
is a recognised but under-considered cause of an isolated, otherwise unexplained enzyme elevation. We describe two cases, one of
macroamylasaemia and one of macro-creatine kinase, both referred after extensive negative investigation for the organ pathology
their elevated enzyme would usually suggest, and both confirmed by polyethylene glycol precipitation testing. We use the two
cases to set out a practical, low-cost diagnostic pathway a laboratory can apply before a patient is referred for invasive
investigation of an isolated enzyme elevation that has already resisted explanation.
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