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General Considerations, Clinical And Medical Classifications Of Anemia
Anemia is defined as a reduction of hemoglobin levels below the normal values for the different age and sex groups. The normal values of hemoglobin for different age groups accepted by WHO are as follows:
- Children 6 months to 6 years: 11g/dl and above
- Children 6 years to 14 years: 12g/dl and above
- Adult males: 13g/dl and above
- Adult females (non-pregnant): 12g/dl and above
- Adult female (pregnant): 11g/dl and above.
In full health, there is no racial variation in hemoglobin. In India and Africa, any hemoglobin level below 12g/dl in adult males and 11.5g/dl in adult females should be diagnosed as anemia and investigated. In general, reduction of hemoglobin is associated with a fall in erythrocyte count and packed cell volume (PCV). In anemic subjects, hemoconcentration, as occurring in dehydration, tends to mask the severity of anemia, so also when there is increase in plasma volume as in pregnancy, there is an apparent fall in hemoglobin level even though the total hemoglobin mass remain normal.
Classification: Based on erythrocyte morphology as seen in the stained blood film, anemias may be classified into micrcocytic hypochromic, normocytic normochromic, macrocytic normochromic and macrocytic hypochromic.
Classification of Anemia based on erythrocyte morphology
Microcytic hypochromic anemia
Iron deficiency, thalasemias, hemoglobinopathies and hemolytic anemia
Normocytic normochromic anemia
Macrocytic normochromic anemia
Folate deficiency, vitamin B12 deficiency, hypothyroidism
Classification of anemia based on etiopathologies
Dyshemopioetic (disorders of erythrocyte formation):
1. Nutritional anemias- Anemias due to deficiency of essential nutrients such as folate, vitamin B12, proteins, vitamin C.
3. Sideroblastic anemia due to metabolic blocks in the synthesis of hemoglobin
1. Acute hemorrhage, eg, antepartum and post partum hemorrhage, bleeding esophageal varices, bleeding peptic ulcer, hemetemesis and melena, traumatic or surgical bleeding.
2. Chronic blood loss, eg, due to intestinal parasites such as hookworms, whipworms and E, histolytica, hemorrhoids, excessive menstrual blood loss and repeated pregnancies.
Hemolytic: Anemias developing because of increased destruction of erythrocytes.
Hypoplastic anemia: Anemias developing because of diminished formation of erythrocytes.
Myelophthisic: Anemias developing as a result of replacement of normal erythropoietic tissue by abnormal tissue, eg, acute leukemias, lymphomas, multiple myeloma, malignant secondaries in bone marrow, myelofibrosis and storage diseases.
© 2014 Funom Theophilus Makama