Pyruvate kinase

PK deficiency is the most commonly encountered inherited defect of the Embden-Meyerhof pathway, with heterozygous frequencies that vary from 0.14 % in the US to 6 % in Saudi Arabia. PK deficiency is probably the most common single known cause of hereditary non-spherocytic haemolytic anaemia. It can be inherited in both an autosomal dominant and recessive fashion.
This disorder manifests clinically as a haemolytic anaemia, but symptoms may be less severe than the haematological indices indicate. The clinical severity of this disorder varies widely, ranging from a mildly compensated anaemia to severe anaemia of childhood. Neuro-developmental abnormalities should be interpreted with caution, as severe neonatal hyperbilirubinaemia, sufficient to cause kernicterus, has been described in deficiency of several red cell enzymes, including G6PD and PK. However, most affected individuals do not require treatment. In the most severe cases, death may occur in utero as a result of anaemia, or blood transfusions or splenectomy may be required, but most symptoms are limited to early life and to times of physiological stress or infection.

Haemolytic anaemia in newborns, infants and juveniles, often with history of jaundice, kernicterus and exchange transfusion
Variable presentation of anaemia, from mild to severe, often associated with growth delay or failure to thrive
Cholecystolithiasis (usually after the first decade of life but possibly in childhood)
More obvious symptoms during times of physiological stress including acute illness (particularly viral) and in pregnancy

6.2-14.2 U/g Hb

Special handling: samples received from outside Imperial College Hospital require an FBC and reticulocyte count result with a blood film and a control sample to monitor transport conditions.