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).
Depression in a child or adolescent is usually in the form of a major depressive disorder, in which multiple, significant symptoms of depression persist nearly every day for at least two weeks. Major depressive disorder affects about two percent of children and about five percent of adolescents.t can develop in response to a stressful situation or it may develop on its own. Many children have symptoms of a milder depression, known as dysthymic disorder, that last for at least one year and impair their functioning at home and at school.