Clinical Information

Erythrocyte (red blood cell: RBC) enzyme deficiencies are inherited causes of hemolytic anemia. Some are very common, such as glucose 6-phosphate dehydrogenase (G6PD) deficiency, and others are very rare, found in only a few families around the world. Most are autosomal in inheritance, but some are sex-linked and located on the X chromosome. Most enzyme deficiencies result in chronic nonspherocytic hemolytic anemia of variable severity; however, some, such as G6PD, can be hematologically normal with episodic acute hemolysis due to a trigger event, such as medications, toxins, or some foods. The RBC enzymopathies do not typically show recurrent pathognomonic changes on the peripheral blood smear other than generic features of hemolytic anemia, although some, such as pyruvate kinase deficiency, can have echinocytes, and pyrimidine 5' nucleotidase (P5NT) deficiency is associated with basophilic stippling. RBC enzyme activity levels are best evaluated as a panel as reticulocytosis can mask some deficient states and comparison to the background enzyme activity is useful.

This is a consultative evaluation of RBC enzyme activity as a potential cause of early RBC destruction.