The chemical and laboratory investigation of hemolysis.

The abnormal breakdown of circulating red blood cells (RBCs), also known as hemolysis, is a significant clinical issue that can present as a primary disorder or arise secondary to another disease process. The evaluation for pathologic hemolysis (and the establishment of a hemolytic disorder) is heavily dependent on assays performed and overseen by the divisions of Hematology, Blood Bank/Transfusion Medicine, Clinical Chemistry, and Immunology in the clinical laboratory. Because of the wide variety of assays used across the spectrum of clinical pathology and potential pitfalls/limitations associated with this testing, the decision of which assay to choose and, perhaps more importantly, how to interpret results, can both be quite challenging. Thus, the aim of this manuscript is to provide a comprehensive review on the laboratory investigation of pathologic forms of hemolysis and hemolytic disorders. This chapter will: (1) introduce basic concepts on the pathophysiology of hemolysis and (2) examine assays available for hemolysis on a laboratory-by-laboratory basis, with a particular emphasis on the strengths, limitations, and clinical interpretations of each of these assays.