Anemia. Definition Is defined as a reduction in one or more of major RBC measurements. Anemia: Is defined as a reduction in one or more of major RBC measurements.

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  • Anemia

  • DefinitionAnemia: Is defined as a reduction in one or more of major RBC measurements.Hemoglobin (Hb).Hematocrit (HCT).Red blood cells count (RBCs)Anemia is not a disease by itself but is one of the major signs of disease.May be the first manifestation of a systemic disease,along with other nonspecific complaints such as fever,weight loss,anorexia.

  • Hb Concentration: measures the major oxygen carrying pigment in whole blood and is expressed as grams of Hb per dL of whole blood.Normal range: M 14-16 gm/dL F 12-14 gm/dL

    Hematocrit (HCT) Is the percent of a volume of whole blood occupied by intact RBCs. Values are expressed as a percentage. Normal range: M 41-51%. F 37-47%.

  • RBCs Count: Is the number of RBCs contained in a unit of whole blood.Values are expressed as millions of cells per uL of whole blood. Normal range: M 4,5-6,5 millions/uL F 3,8-5,8 millions/uL

  • Special considerationsVolume status.Living at high altitude.Smoking and air pollution.African-Americanslower values.Populations with a high incidence of chronic diseases.Athletes.The elderly:should not have a lower normal range for fear of missing a serious underlying disorder.

  • ERYTHROPOESISErythropoesis takes place in adults within the BM under the influence of the stromal framework, a number of cytokines, and the eryrhroid specific growth factor, erythropoietin(EPO).EPO is a true endocrine hormone produced in the kidney.

  • ERYTHROPOESISThe rate of RBC production equals the rate of RBC destruction.Approximately 1% of RBCs is removed from the circulation daily.The rate of RBC production can be increased markedly (5-7 folds).

  • CLINICAL CONSEQUENCES OF ANEMIAThe symptoms caused by anemia depend on both the degree of anemia and the rate at which the anemia developed.

    Symptoms of anemia can result from two factors:1.Decreased O2 delivery to tissues.2.Hypovolemia (acute bl.loss).

  • COMPENSATORY MECHANISMSSigns and symptoms depend also on the compensatory mechanisms.1.Extraction of O2 by the tissues can increase from 25% to 60%.2.Cardiac compensation: stroke volume and heart rate (cardiac output).

  • Symptoms and SignsSymptoms:Dyspnea: on exersion/at rest.Fatigue/tiredness, palpitations, angina, headache.Dizziness

    Signs:Tachycardia, Pallor, Hypotension, decreased capillary refilling.

  • CAUSES OF ANEMIA1. Kinetic approach.2. Morphologic approach.

  • KINETIC APPROACHAnemia can be caused by one or more of 3 independent mechanisms.1.Decreased RBC production.2.Increased RBC destruction.3.RBC loss.

  • Decreased RBC PRODUCTIONIf less than 1% of the circulating RBCs isreplaced by the BM. 1- Lack of nutrients such as iron,B12,or folate. 2- Primary involvement of the BM such as aplastic anemia,PRCA,MDS,or tumor infiltration. 3- Low levels of trophic hormones,such as EPO in CRF,thyroid hormones,and androgens.

  • INCREASED RBC DESTRUCTIONA RBC life span below 100 days is the operational definition of hemolysis.Anemia will ensue when the BM is unable to keep up with the need to replace more than 5% of the RBC mass daily. 1-Inherited hemolytic anemias: hereditary spherocytosis,SCD,and thalassemia major. 2-Aquired hemolytic anemias: AIHA,TTP.

  • RBCs LOSSBlood loss is the most common cause of anemiaForms of bleeding: 1-Obvious bleeding: trauma,melena, hematemesis,or menometrorrhagia. 2-Occult bleeding: a slowly bleeding colonic polyp or carcinoma. 3-Iatrogenic bleeding: Excessive bl. donations,or repeated venesction

  • MORPHOLOGIC APPROACHAccording to RBCs sizeMean Corpuscular (Cell) Volume (MCV).

    RBC size (MCV) is 80-96 femtoliters(fL).Microcyte Microcytic anemiaMacrocyte Macrocytic anemiaNormocyte Normocytic anemia.

  • MICROCYTIC ANEMIASAre associated with a MCV below 80 fL. 1-Iron Deficiency Anemia (IDA) 2- Anemia of Chronic Disease (ACD) 3-Thalassemias.

  • IRON DEFICIENCY ANEMIA (IDA)Important discriminating features are: 1-Low serum ferritin concentration. 2-Increased total iron binding capacity (TIBC). 3-Low serum iron concentration. 4-High RDW.

    It is mandatory to determine the cause of iron deficiency.

  • ANEMIA OF CHRONIC DISEASE (ACD)The hallmarks of this condition are: 1-Low serum iron. 2-Low TIBC. 3-Normal to increased serum ferritin concentration.The causes are usually related to the presence of chr.infection (TB), inflamation (RA), or malignancy.

  • MICROCYTIC ANEMIASAre associated with a MCV below 80 fL. 1-Iron Deficiency Anemia (IDA) 2- Anemia of Chronic Disease (ACD) 3-Thalassemias.

  • NORMOCYTIC ANEMIASBy definition the MCV is normal. Anemia of chronic disease (ACD). Myelodysplastic syndrome (MDS)

  • MACROCYTIC ANEMIASAre characterized by an MCV above 100 fL. Vit.B12 def. Folate def. MDS. Hypothyroidism


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