Macroenzymes: biochemical characterization, clinical significance, and laboratory detection.

"Macroenzymes" are enzymes in serum that have formed high-molecular-mass complexes, either by self-polymerization or by association with other serum components. Many enzymes in serum that are measured in clinical chemistry laboratories can occur in a macroenzyme form. Macroenzymes are interesting clinically because of their association with several diseases, including autoimmune diseases and liver disease, and are being investigated as possible diagnostic markers. Most importantly, macroenzymes frequently interfere with the interpretation of serum enzyme results, and as a result can cause diagnostic and therapeutic errors. We review the biochemical characterization, clinical significance, and laboratory detection of macroenzymes.