Anemia

Definition

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

• Hemoglobin (Hb).Hemoglobin (Hb).• Hematocrit (HCT).Hematocrit (HCT).• Red blood cells count (RBCs)Red blood cells count (RBCs)

Anemia is not a disease by itself but is one of the Anemia is not a disease by itself but is one of the major signs of disease.major signs of disease.

May be the first manifestation of a systemic May be the first manifestation of a systemic disease,along with other nonspecific complaints disease,along with other nonspecific complaints such as fever,weight loss,anorexia.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 considerations

• Volume status.Volume status.• Living at high altitude.Living at high altitude.• Smoking and air pollution.Smoking and air pollution.• African-Americans—lower values.African-Americans—lower values.• Populations with a high incidence of chronic Populations with a high incidence of chronic

diseases.diseases.• Athletes.Athletes.• The elderly:should not have a lower normal The elderly:should not have a lower normal

range for fear of missing a serious range for fear of missing a serious underlying disorder. underlying disorder.

ERYTHROPOESIS

Erythropoesis 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.

ERYTHROPOESIS

• The rate of RBC production equals the The rate of RBC production equals the

rate of RBC destruction.rate of RBC destruction.• Approximately 1% of RBCs is removedApproximately 1% of RBCs is removed

from the circulation daily.from the circulation daily.• The rate of RBC production can be The rate of RBC production can be

increased markedly (5-7 folds). increased markedly (5-7 folds).

CLINICAL CONSEQUENCES OF ANEMIA

• The 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 MECHANISMS

Signs 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 Signs

• Symptoms:

Dyspnea: on exersion/at rest.

Fatigue/tiredness, palpitations, angina, headache.

Dizziness

• Signs:

Tachycardia, Pallor, Hypotension, decreased capillary refilling.

CAUSES OF ANEMIA

1. Kinetic approach.

2. Morphologic approach.

KINETIC APPROACH

Anemia can be caused by one or more of 3 independent mechanisms.

1.Decreased RBC production.

2.Increased RBC destruction.

3.RBC loss.

Decreased RBC PRODUCTION

If 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 DESTRUCTION

• A 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 LOSS

• Blood loss is the most common cause of anemia

• Forms 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 APPROACH

According to RBCs’ sizeAccording to RBCs’ size

Mean Corpuscular (Cell) Volume (MCV).Mean Corpuscular (Cell) Volume (MCV).

RBC size (MCV) is 80-96 femtoliters(fL).RBC size (MCV) is 80-96 femtoliters(fL).

Microcyte Microcyte Microcytic anemiaMicrocytic anemia

Macrocyte Macrocytic anemiaMacrocyte Macrocytic anemia

Normocyte Normocytic anemia.Normocyte Normocytic anemia.

MICROCYTIC ANEMIAS

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

• It is mandatory to determine the cause of It is mandatory to determine the cause of iron deficiency.iron deficiency.

ANEMIA OF CHRONIC DISEASE ANEMIA OF CHRONIC DISEASE (ACD)(ACD)

• The hallmarks of this condition are:The hallmarks of this condition are: 1-Low serum iron.1-Low serum iron. 2-Low TIBC.2-Low TIBC. 3-Normal to increased serum ferritin3-Normal to increased serum ferritin concentration.concentration.• The causes are usually related to the The causes are usually related to the presence of chr.infection (TB),presence of chr.infection (TB), inflamation (RA), or malignancy.inflamation (RA), or malignancy.

MICROCYTIC ANEMIAS

• Are associated with a MCV below 80 fL.

1-Iron Deficiency Anemia (IDA)

2- Anemia of Chronic Disease (ACD)

3-Thalassemias.

NORMOCYTIC ANEMIAS

By definition the MCV is normal.

Anemia of chronic disease (ACD).

Myelodysplastic syndrome (MDS)

MACROCYTIC ANEMIASMACROCYTIC ANEMIAS

Are characterized by an MCV above 100 fL.Are characterized by an MCV above 100 fL.

Vit.B12 def.Vit.B12 def.

Folate def.Folate def.

MDS.MDS.

HypothyroidismHypothyroidism