Pyruvate kinase deficiency is a genetic blood disorder characterized by low levels of an enzyme called pyruvate kinase, which is used by red blood cells. Without pyruvate kinase, red blood cells break down too easily, resulting in low levels of these cells (hemolytic anemia). The signs and symptoms of the disease may vary greatly from person to person. However, they usually include jaundice, enlargement of the spleen, and mild or severe hemolysis (red cell breakdown), leading to anemia.

In some cases, the problems may first appear while in utero, causing a condition in which abnormal amounts of fluid build up in two or more body areas of the fetus (hydrops fetalis). Newborns may present with prolonged jaundice and anemia. Older children may be pale (due to anemia) and have intermittent episodes of jaundice. Mild cases may escape detection until adulthood. Although the anemia tends to stabilize in adulthood, episodes of anemia may occur with acute infections, stress, and pregnancy. Pyruvate kinase deficiency is caused by a mutation in the PKLR gene and is inherited in an autosomal recessive fashion. Treatment remains supportive rather than curative.

Mild cases require no treatment. People with severe anemia may need blood transfusions. In newborns with dangerous levels of jaundice, a health care provider may recommend an exchange transfusion. Surgical removal of the spleen (splenectomy) may also be necessary to help reduce the destruction of red blood cells. However, this does not help in all cases. With small children, this is delayed as long as possible to allow the immune system to mature. Other treatment is symptomatic and supportive. Someone who had a splenectomy should receive the pneumococcal vaccine at recommended intervals. They also should receive preventive antibiotics until age 5.