Anamia and its classification

Anemia

Definition:

          Anemia is the condition in which hemoglobin level in blood or red cell count is below the normal range for age and sex causing reduction in oxygen-transporting capacity of blood. 

Classification

A) According to etiology:

1) Blood Loss:

•         Acute: trauma

•         Chronic: lesions of GIT, gynecologic disturbances

2) Increased Destruction (Hemolytic Anemias)

            a) Intrinsic (intracorpuscular) abnormalities

                        i) Hereditary

                        Membrane abnormlities

                         -Membrane skeleton proteins:                         spherocytosis, elliptocytosis

                        -Membrane lipids: abetalipoproteinemia

           Enzyme deficiencies

                         pyruvate kinase, hexokinase, G6PD    deficiencies.

            Disorders of hemoglobin synthesis

                        -Deficient globin synthesis: thalassemia          syndromes

                        -Structurally abnormal globin synthesis          (hemoglobinopathies): sickle cell anemia

ii) Acquired

            Membrane defect: paroxysmal nocturnal hemoglobinuria

b) Extrinsic (extracorpuscular) abnormalities

            i) Antibody mediated

                        transfusion reactions, Rh disease of     newborn, drug-associated

            ii) Mechanical trauma to red cells

                        Microangiopathic hemolytic anemias

            iii) Infections: malaria

3) Impaired Red Cell Production

            a) Disturbance of proliferation and differentiation of stem cells: aplastic anemia, pure red cell aplasia, anemia of renal failure, anemia of endocrine disorders.

            b) Disturbance of proliferation and maturation of erythroblasts

                        i) Defective DNA synthesis:                     megaloblastic anemias

                        ii) Defective hemoglobin synthesis

                                    Deficient heme synthesis: iron                           deficiency

                                    Deficient globin synthesis:                                               thalassemias

                                    Anemia of renal failure

B) According to morphology:

            1) Normocytic normochromic- hemolytic      anemia (MCV, MCHC,MCH-normal)

            2) Microcytic hypochromic anemia-Iron        deficinecy anemia, thalessamia             (MCV,MACHC, MCH-below normal)

            3) Macrocytic anemia-megaloblastic   anemia (MCV-above normal,MCHC-    normal)