Polycythemia (also known as polycythaemia or polyglobulia) is a disease state in which the proportion of blood volume that is occupied by red blood cells increases. Blood volume proportions can be measured as hematocrit.It can be due to an increase in the number of red blood cells (absolute polycythemia) or to a decrease in the volume of plasma (relative polycythemia).lood volume proportions can be measured as hematocrit. It can be due to an increase in the number of red blood cells (absolute polycythemia) or to a decrease in the volume of plasma (relative polycythemia).
1 Some 20% of adolescents with major depression develop bipolar disorder within five years of the onset of depression. ( 2 Birmaher, B., Childhood and Adolescent Depression: A Review of the Past 10 Years.. 3  Part I, 1995).
Age. Bipolar disorder usually first occurs between the ages of 15 - 30 years, with an average age of onset at 25 years. However, bipolar disorder can affect people of all ages, including children. Bipolar disorder that occurs late in life often accompanies medical and neurological problems (particularly cerebrovascular disease, such as stroke). It is less likely to be associated with a family history of the disorder than earlier-onset bipolar disorder.