Macroamylasemia is the presence of serum amylase of a large molecular size, seen in both otherwise healthy individuals, and also in various diseases. Amylase seems to be able to self-polymerize and/or form immune complexes with immunoglobulins.
The normal amylase molecule has a molecular weight of 45 kDa, but in hyperamylasemia the amylase forms a complex with globulin forming a much larger macromolecule ~200 kDa. This is too large to be filtered by the renal tubules resulting in a normal urinary amylase despite the apparently elevated serum amylase.
This condition can be confused with other causes of raised serum amylase (e.g. acute pancreatitis). Macroamylasemia is accompanied by normal serum lipase and urinary amylase levels. Where as in pancreatic disease lipase will usually be elevated as well 2.
Causes of macroamylasemia
- liver disease
- diabetes mellitus
- autoimmune disorders