•Primary polycythemia — Primary polycythemia is caused by a mutation in RBC progenitor cells that results in increased RBC mass.

•Secondary polycythemia — Secondary polycythemia refers to an increase of RBC mass caused by elevated serum EPO. Most often, this is due to an appropriate physiologic response to tissue hypoxia.

When there is severe bleeding regardless of the cause the clotting factors V and V111 , fibrinogen and platelets migrate to the site to form a plug . Most time these clotting factors are fully consumed with subsequent clot formation. As a result of these clot formation plasmin is released. Plasmin is designed to breakdown fibrinogen and prevent clots. As a result of fibrinogen being broken down by plasmin, platelet aggregation is inhibited, fibrin polymerization is inhibited and thrombin is inhibited. This leads to uncontrolled bleeding. So DIC starts with bleeding, consumption of clotting factors, micro clot formation, the release of plasmin and finally the inhibition of platelets, fibrin and thrombin with full blown hemorrhage as the end result.

Impaired Platelet Function.

Impaired function of platelets may be hereditary or acquired.

The two most common inherited disorders of bleeding are ;

1.Von Willebrand disease ( v.WF defect)

2.Hemophilia A ( factor V111 deficiency) and B ( factor IX deficiency)

●

Von Willebrand Disease.

Von Willebrand factor is synthesized by the endothelium and megakaryocytes and is required for the adhesion of platelets to the walls of damaged blood vessels. If platelets cannot adhere to the site of bleeding and create a plug then bleeding will continue.

1.This is a reduction in platelet number below 150,000/micro liter

2.Thrombocytopenia may be due to bone marrow dysfunction from radiation and chemotherapy.

3.Thrombocytopenia may be due to increase pooling of platelets in the spleen

4.Thrombocytopenia may be due to antibodies against platelets that facilitate destruction. These antibodies attack the glycoprotein 11b/111a receptors on the surface of the platelets.

5.Thrombocytopenia may be due to some drugs like aspirin and atorvastatin.

6.Thrombocytopenia may be due to heparin.

Thrombocytopenia may be due to immune thrombocytopenic purpura( ITP). In this condition antibodies bind to platelets and cause excess destruction. This is an autoimmune disease. Itscalled primary ITP. This affect both genders and all ages. The platelet–antibody complex that is formed exposed the platelets to phagocytosis in the spleen.

This condition is caused by uncontrolled platelet aggregation which is responsible for generalized vascular occlusion and organ failure

Bleeding Relating To Platelets May Be Due To:

1. Decrease in platelet production

2. Increase in platelet destruction

3. Impaired platelet function

•Non-Hodgkin lymphomas (NHL) are a group of malignant tumors derived from

•B cell progenitors,

•T cell progenitors,

•mature B cells,

•mature T cells,

•or (rarely) natural killer cells.

•NHL is seen in patients of all ages, races, and socioeconomic status.

1. ALL--most common in children, response best to treatment

2.AML

3. CLL

4. CML