It is found in hardworking hyperactive middle-aged “males.

It is also known as Christmas disease. It is due to deficiency of factor IX. It is carried by females and affects males. In case of haemophilia B activated partial thromboplastin time (PTTK) is raised. In a severe case, whole blood clotting time is raised.

But, the bleeding time and prothrombin time tests are normal. Since factor IX is stable in stored blood. The treatment of haemophilia B includes the transfusion of factor IX concentrates, or stored plasma.

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Polycythemia is also known as erythrocytosis. This condition is indicated by raised haemoglobin, PCV and red cell count.

The values are above those normal for age and sex. The polycythemic condition can be classified as:

1. Relative polycythemia

2. Absolute polycythemia

Relative Polycythemia:

It is caused by decrease in plasma (fluid part) of the blood. The number of red cells in the blood is not increased, but the number of cells per unit volume of blood is increased. This is observed in dehydration, due to stress. Polycythemia, which is found in hardworking hyperactive middle-aged “males.

The RBCs are normochromic, normocytic. Morphologically, white cells, red cells and platelets are normal. The haemoglobin, PCV and red cell count is elevated. Bone marrow is normal.

Absolute Polycythemia:

Absolute polycythemia can be further divided as:

i. Primary polycythemia

ii. Secondary polycythemia

Primary Polycythemia:

It is a chronic disease of unknown origin and found most often in patients over 60 year of age. In this case, blood volume is increased, while there is no change in volume of plasma.

Blood pressure is increased with elevated platelet count. RBCs are normocytic normochromic. Occasional nucleated red cells, immature granulocytes and anisocytic RBCs are seen. Increase in red cell count, haemoglobin, PCV is observed. Bone marrow activity is hypercellular.

Secondary Polycythemia:

It is caused by an increased level of erythropoietin due to decreased capacity of haemoglobin molecule to carry oxygen. Haemoglobin in this case may be abnormal. Tumors of liver, brain and pituitary gland or renal carcinoma may be observed. It is often associated with respiratory failure and chronic heart disease.