The word "anemia" comes from the Greek term which means missing blood. Anemia is defined as a lower than normal hemoglobin concentration. The lower end of the normal rage is g/L in men and g/L in women. It is primarily important to distinguish pseudo-anemia and/or relative anemia (decreased hemoglobin concentrations as a result of increased plasma volume) from absolute anemia (decreased hemoglobin concentrations with a normal plasma volume). Relative anemia is typically observed during pregnancy (iron deficiency usually exists) and during infusion of large amounts of fluids.


Anemias can both be classified based on their morphological criteria (erythrocyte indices) as well as pathophysiologic criteria.
Classification based on erythrocyte indices
Low MCV + Low MCH 
microcytic + hypochromic
Iron deficiency anemia
Normal MCV  + Normal MCH 
normocytic + normochromic
acute blood loss
Anemia of chronic disorder, anemia of renal disease
 Hemolysis  (partially macrocytic)
Bone marrow infiltration
Increased MCV 
Megaloblastic anemia
Classification based on pathophysiology
1. Increased cell loss or destruction a) Internal or external bleeding
b) Hemolysis (immunologic, hereditary, mechanical)
c) Hypersplenism (combination of hemolysis and sequestration)
2. Decreased and/or
 ineffective production
a) Proliferation and differentiation defects (aplastic anemia, myelodysplastic syndrome, anemia of renal disease)
b) DNA synthesis defect (vitamin B12 deficiency, folic acid deficiency),
c) Hemoglobin synthesis defect ( iron deficiency, thalassemia)
d) Uncertain or various mechanisms (anemia of chronic disorder, leukemia, bone marrow infiltration through tumors and malignant lymphomas)

Clinical picture:
The symptoms are caused by hypoxia due to a decrease in hemoglobin concentration. Cardiac hyperactivity causes palpitations, tachycardia and heart murmurs. Other symptoms range from weakness, fatigue, and exercise intolerance or even dyspnea at rest. A pallor is the result of vasoconstriction which reroutes the blood to the oxygen dependent organs. Cardial hyperactivity causes palpitations, tachycardia and heart murmurs.


Severity of anemia:
The severity of an anemia is relative and depends on one side on the state of health and the comorbidities of the patient and on the other side on the duration of the anemia (adaptation). Acute anemias (e.g. bleeding or hemolysis) cause more severe symptoms than anemias that developed over a longer period of time (e.g. anemia of chronic disorders). In otherwise healthy patients, the following graduation can be expected:

Light anemia (grade 1): Hb >100 g/l Symptoms only in extreme exercise
Medium anemia (grade 2):     Hb 80 – 100 g/l  Mild symptoms in rest
Severe anemia (grade 3): Hb 60 – 80 g/l Severe symptoms in rest
Life threatening anemia (grade 4): Hb <60 g/l  


The various forms of anemia differ quite a bit from each other, particularly in the peripheral blood film. A diagnosis can often be established at this stage. However, this must still be confirmed by specific supplementary tests.