Microangiopathic Hemolytic Anemia in Rats with Malignant Hypertension

Unilaterally nephrectomized rats given desoxycorticosterone and salt load developed malignant hypertension with widespread vascular lesions and, coincidentally, a hemolytic anemia. The anemia was characterized by red cell fragmentation, increased erythrocyte osmotic fragility, and evidence of both intravascular and extravascular hemolysis. Thrombocytopenia was not observed. Male rats were more severely affected than female animals. The degree of anemia correlated well with the severity of the vascular lesions, but not with the level of blood urea nitrogen.

Based upon electron microscopic observations of the relationship of red cells to damaged endothelial cells and thrombi, possible mechanisms for the red cell fragmentation are discussed.