pyruvate kinase (PK) deficiency

A glycolytic defect --> congenital non-spherocytic haemolytic anaemia

 

pathophysiology

PK converts phosphoenolpyruvate to pyruvate, creating 50% of red cell's ATP

Red cell longevity is reliant on ATP availability --> shortened life span

Younger cells are more dependent on ATP & so more affected by deficiency

Travel through the splenic capillaries damages affected cells --> removal from circulation by liver and spleen

 

Autosomal recessive

50 cases per 1 million of general population. Increased in Amish and Romani groups

Over 200 known causative mutations

 

clinical features

Highly variable between individuals

- Prenatal hydrops fetalis

- Neonatal hyperbilirubinaemia --> phototherapy and exchange transfusion

- Children can be transfusion-dependent for years, even after splenectomy

- Stabilises in adulthood

 

investigation

Blood film - may be normal or typical of PK (prominent echinocytes, increased after splenectomy

PK Enzyme activity test

PK-LR gene testing

 

treatment

Folic acid

Splenectomy (consider cholecystectomy at time of surgery)

Iron overload management

Pregnancy - increased haemolysis so care required but successful pregnancies are possible

Manage extramedullary haematopoeisis (leg ulcers, spinal cord compression)