G6pd deficiency
Also called FAVISM
G6PD is an enzyme of hexose monophosphate shunt .It is needed for the synthesis of REDUCED GLUTATHION which protects RBCs membrane and Hb against oxidative damage .
It is X-linked recessive affected mainly males , but can occur in females .
The hemolysis is intravascular .
The RBCs become liable to destruction by O2 radicles .
The defect is either functional ( the enzyme is not functioning ) or quantitative( the quantity of enzyme is not enough ) .
Precipitatng factors for hemolysis :
Usually the patient is normal and there is no hemolysis except in :1- Ingestion of favabeans ( usually fresh ) , leads to liberation of O2 radicles leading to RBCs damage .
2- infections : It leads to increased activity of neutrophils which will try to combat the infection by liberation of O2 radicles causing RBCs damage .
3- Drugs :
** Antimalarial : primaquine , chloroquine .** Analgesics : Aspirin , phenacetin
** Antibiotics : Sulphonamides , nitrofurantoin , ciprofloxacin
** Miiscellaneous : quinidine , vitamin K , dapsone
4- Surgery and stressful conditions .
Clinical features :
The patient is normal but when exposed to the any of the above precipitating factors , there will be sudden and rapidly developing anemia , jaundice , fever and dark urine due to hemoglobinuria .Investigations :
1- Anemia .2- Reticulocytosis .
3- Increased indirect bilirubin .
4- Increased LDH .
5- Blood film : ** Heinz bodies
** bite cells
6- Enzyme assays ( definitive diagnosis ) .
In patients with active hemolysis , the enzyme assay will be normal because there are some RBCs are enzyme deficient and other RBCs are normal , so when hemolysis occurs the only abnormal RBCs are destroyed and the normal will stay , so when we do the enzyme assays we will find normal enzyme assay , so we should wait for one month at least after active hemolysis and then do the test .Also following blood transfusion , the test will be normal .
treatment
1- Avoid precipitating factors .2- For acute attacks :
Rest
Withdrawal of the drugs
Blood transfusion for symptomatic anemia
folic acid