Cytochrome b5 reductase
Cytochrome b5 reductase is an enzyme in the blood. It controls the amount of iron in your red blood cells, and helps the cells carry the normal amount of oxygen.
People who do not have enough of this enzyme may develop a condition called methemoglobinemia.
References
Means Jr. RT. Approach to the anemias. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 144.
Smith-Whitley K, Kwiatkowski JL. Hemoglobinopathies. In: Kliegman RM, St. Geme JW, Blum NJ, et al, eds. Nelson Textbook of Pediatrics. 22nd ed. Philadelphia, PA: Elsevier; 2025:chap 511.