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Polycythemia vera | Polycythemia | Ayerza disease

POLYCYTHEMIA-
Increase in RBC count is called polycythemia.
> Increase in RBC count occurs in these conditions-
A. Physiological variation
B. Pathological variations

A. Physiological variations
When RBC count increases in physiological conditions it is called physiological polycythemia.
• increase in RBC count in this condition is temporary or marginal.
It occurs in following conditions-
1. Age
RBC count at birth= 8-10 million/cu mm of blood
• in infants and growing childrens RBC count is more than adults.
[RBC] infants > [RBC] adults
* Physiological jaundice
Because, Within 10days after birth RBC counts decrease due to destruction of RBCs.
2. High altitude
Due to hypoxia ( decreased oxygen supply to tissue) RBC count in High altitude resedents, above 10000 feet from sea level( mountains)
 = >7 million/cu mm
• Hypoxia stimulates kidney for secretion of erythropoietin hormone.
• erythropoietin hormone stimulates the bone marrow for production of RBCs.

3. Sex
✓ during reproductive period
[RBC] males > [RBC] females
✓ before puberty or after menopause
[RBC] males = [RBC] females
4. Emotional conditions
RBC counts increases during emotional conditions, because of increase in sympathetic activity.
5. Muscular exercise
Because of hypoxia and contraction of spleen a temporary increase in RBC count seen after exercise.
• RBCs stores in spleen.
•  due to hypoxia sympathetic activity increases that results in secretion of adrenaline hormone from adrenal medulla.
• adrenaline contracts the spleen and RBCs are released into blood.


6. After intake of food or meal
After intake of food oxygen requirements increases for metabolic activities, so there is slight increase in RBC count after taking food.
7. Increase in environmental temperature
If environmental temperature increases , all the activities of body increase, like RBC counts.

B. Pathological variations
Abnormal increase in RBC count is called pathological polycythemia.
RBC count > 7million/cu mm of the blood.
Two types-
1. Primary polycythemia
2. Secondary polycythemia

1. Primary polycythemia
[ Polycythemia vera]
• in this type RBC count is persistently increase above the 14 million/cu mm.
✓ polycythemia vera is always associated with increased WBC count above 24,000/ cu mm.
* Polycythemia vera occurs in myeloproliferative disorders like melignancy of red bone marrow.
2. Secondary polycythemia
This occurs in following disease-
a. Respiratory disorders (emphysema)
b. Chronic CO poisoning (carbon monoxide)
c. Poisoning by chemicals (phosphorus and arsenic)
d. Repeated mild hemorrhages.
e. Congenital heart disease
f. Ayerza disease
(Conditions associated with right ventricular hypertrophy and obstruction of blood flow to lungs)

> All above disease leads to hypoxia, which stimulates the release of erythropoietin.
> Erythropoietin stimulates the bone marrow that results in increased RBC counts.

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