The red cell indices. Yesterday, today, and tomorrow.

The red cell indices of mean corpuscular volume, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration have been standard methods of evaluating anemia since they were developed by Wintrobe in the 1930s. This article discusses the technical variabilities that have rendered the classic red cell indices less useful than was originally claimed for the differential diagnosis of anemia; examines the literature regarding the diagnostic utility of the newer indices; and suggests possible newer indices that may be added to routine hematology analyzers to render the information they generate more clinically useful.