Blood

A person may develop leukopenia due to the following conditions: autoimmune conditions, such as rheumatoid arthritis, lupus, and Sjögren's disease. cancers, such as Hodgkin lymphoma, leukemia, and myelofibrosis. infection, such as influenza, HIV, and hepatitis.

Polycythemia, or erythrocytosis, means having a high concentration of red blood cells in your blood.

Primary polycythemia is caused by neoplastic disease of the pluripotent cells of the bone marrow, that start to over-produce red blood cells accompanied by elevated white cell and platelet count. 

Secondary polycythemia is caused as a compensatory response to hypoxia with increase in the level of erythropoietin. Hypoxia may be result of leaving at high altitude, chronic heart and lung disease, and smoking. 

Primary polycythemia

Increase in the red blood cell count (due to neoplastic disease of stem cells) → hemoglobin level ↑ | blood volume ↑ | viscosity ↑ | hematocrit ↑ → large ↓ in cardiac output and blood flow (pripary due to viscosity ↑) → such symptoms: 

• hypertension;
• headache;
• dizziness;
• inability to concentrate;
• difficulty with hearing and vision ← due to ↓ cerebral blood flow

Venous stasis^[1] → visual changes of body tissue color:

• plethoric appearance of dusky redness, even cyanosis (lips, fingernails, mucous membrane);

↑ concentration of blood cells → itching, pain in the fingers or toes

hypermetabolism → night sweats, weight loss. 

[1] Venous stasis - condition in which veins have problems moving blood back to the heart

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Secondary polycythemia

Hypoxia (altitude, smoking, lung disease) → release of erythropoietin^[2] by kidney → increase formation of red blood cells in BM → symptoms:

• Fatigue;
• Headache;
• Dizziness;
• Blurred vision;
• Weakness;
• Reduced mental acuity

[2] Erythropoietin - a hormone secreted by the kidneys that increases the rate of production of red blood cells in response to falling levels of oxygen in the tissues

Thrombocytosis is a disorder in which body produces too many platelets (count above 1.000.000/μL)

The most common underlying causes of secondary thrombocytosis include:

• tisue damage due to surgery;
• infection;
• cancer;
• chronic inflammatory conditions: rheumatoid arthritis (inflammation or swelling of one or more joints) and Crohn disease. 

Primary thrombocytosis is caused by abnormalities in thrombopoietin receptor and platelet binding, causing hihger-than-expected levels of free thrombopoietin.