MCQ 31 All of the following are the causes of relative Polycythemia except:

A.Dehydration
B.Dengue hemorrhagic fever
3.Gaisbock syndrome
D.High altitude

The correct answer is D.High altitude


Note: Polycythemia is defined as an increase in Hb,PCV and red cell count.Often this term is reserved for Plycythemia Vera.


Polycythemia classified as i)Absolute Polycyhemia and ii)Relative Polycythemia.


Absolute Polycythemia:There is increase in the Red cell mass.It is of two types:
a)Primary Polycythemia which is also known as Polycythemia Vera,is a myeloprolifeative disorder.
b)Secondary Polycythemia occurs due to hypoxia or due to increased production of Erythropoietin(EPO).


Relative Polycythemia: It occurs due to decrease in the plasma volume but the red cell volume is normal.


The causes of Primary,Secondary and Relative Polycythemia given below:
Primary:

• Polycythaemia vera
• Mutations in erythropoietin
• receptor
• High-oxygen-affinity
• haemoglobins

Secondary(Due to an appropriate increase in erythropoietin):

• High altitude
• Lung disease
• Cardiovascular disease
• (right-to-left shunt)
• Heavy smoking
• Increased affinity of
• haemoglobin, e.g.
• familial polycythaemia

Secondary (Due to an inappropriate increase in erythropoietin):

• Renal disease–renal cell
• carcinoma, Wilms’ tumour
• Hepatocellular carcinoma
• Adrenal tumours
• Cerebellar haemangioblastoma
• Massive uterine fibroma

Relative:

• Stress or spurious
• polycythaemia
• Dehydration
• Burns
• Gaisböck’s syndrome