Differences in Distribution of Erythropoietic and Reticuloendothelial Marrow in Hematologic Disease

Although reticuloendothelial cells are an invariable component of normal marrow, the distribution of phagocytic acitivity may or may not correspond to the distribution of erythropoietic activity in the presence of disease affecting the marrow. A direct comparison of the distributions of reticuloendothelial marrow (using Tc^99m-sulfur colloid) and erythropoietic marrow (using Fe⁵²) in patients receiving treatment for various diseases affecting the bone marrow has been made. In the presence of hematologic disease, the correlation between the distributions of these two marrow functions has varied from identical to totally dissimilar.

Unless one is studying normal subjects, knows a priori that marrow composition is normal, or is specifically studying the reticuloendothelial component of the marrow, one must be cautious in equating marrow distributions obtained with colloidal material with erythropoietic marrow distribution.