MLAB 1315- Hematology Keri Brophy-Martinez Unit 7: Anemia

Anemia Anemia is the inability of the blood to supply the tissue with adequate oxygen for proper metabolic function. Clinically, anemia is defined as a decrease in normal concentration of hemoglobin or erythrocytes. Anemia is not a disease, but an expression of an underlying disorder or disease.

Development of Anemia Anemia occurs if: Erythrocyte loss or destruction exceeds the maximum capacity of bone marrow erythrocyte production Bone marrow erythrocyte production is impaired.

Anemia Two laboratory tests used to measure anemia Hemoglobin Normal values Male: 14-18 g/dl Female: 12-16 g/dl Moderate anemia: 7-10 g/dl Severe anemia: <7 g/dl Hematocrit - the proportion of red cells in whole blood expressed as a percentage (packed red cell volume) Male: 42-52% Female: 37-47%

Causes of anemia Acute blood loss (hemorrhage) Accelerated destruction of RBC’s (immune or non-immune) Nutritional deficiency (iron, folate or B12) Bone marrow replacement (e.g. cancer) Infection Toxicity Hematopoietic stem cell arrest or damage Hereditary or acquired defect

Diagnosis of anemia Clinical history Physical signs such as pallor, fatigue, weakness and shortness of breath Laboratory tests CBC Examination of the blood smear Reticulocyte - measures effective erythropoiesis Bone marrow examination Iron studies - iron, total iron-binding capacity (TIBC), ferritin Vitamin B12 and folate Erythropoietin level

Parameters of the CBC (complete blood count) used to diagnose anemia Hemoglobin Hematocrit Note: the approximate relationship of the hemoglobin to the hematocrit is 1:3. This may vary with the cause of the anemia and the effect on the RBC indices, especially the MCV. RBC indices MCV - mean cell volume Normal: male - 80-94 fl, female - 81-99 fl) Indicates the average size (volume) of the red cells Calculation: Hct x 10 RBC

RBC Indices con’t MCH - mean cell hemoglobin weight Normal: 27-31 pg A measurement of the hemoglobin content in RBC’s Calculation: Hgb x 10 RBC MCHC - mean cell hemoglobin concentration Normal: 32-36 % A measure of the concentration of hemoglobin in the average RBC Calculation: Hgb x 100 Hct

Examination of the RBC’s in the peripheral blood smear Alteration in size of the RBC is called anisocytosis. Alteration in shape of the RBC is called poikilocytosis. An RBC with normal hemoglobin content will appear normochromic (MCHC 32-36). An RBC with decreased hemoglobin content will appear hypochromic (MCHC <32). RBC size is designated as microcytic (small MCV <80), normocytic (normal size MCV 80-100), or macrocytic (large MCV >100).

Classification of anemia by RBC indices Normal size and color: normocytic/normochromic Causes: bone marrow failure, hemolytic anemia, chronic renal failure, leukemia, metastatic malignancy Increased size, normal color: macrocytic/normochromic Causes: Folate or B12 deficiency, liver disease Decreased size, decreased color: microcytic/hypochromic Most common anemia Causes: iron deficiency, sideroblastic anemia, thalassemia, chronic diseases

RBC inclusions are seen on Wright-stained smears in certain anemias RBC inclusions are seen on Wright-stained smears in certain anemias. Discussion to follow.

Reticulocyte Adult normal: 0.5 - 1.5% Useful in determining the response to the anemia and the potential of the bone marrow to manufacture RBC’s. Expressed as a percentage of the RBC’s. When anemia is present, it is helpful to correct the retic using the patient’s hematocrit in order to assess appropriate bone marrow response A supravital stain called New Methylene Blue is used to stain reticulocytes. On a Wright’s stained smear, reticulocytes appear as bluish red cells. The term used for retics on Wright’s stain is polychromasia. Corrected retic% = retic % X Patient hct Normal hct* based on age and sex [*Normal female hct = 42%] [*Normal male hct = 45%]

maturation time in days Reticulocyte Prematurely released retics remain in the blood and take from ½ to 1 ½ days longer to mature. This will cause even the “corrected” retic to be elevated, so a calculation must be performed to correct for this situation to obtain the reticulocyte production index (RPI). A maturation time table is used for this calculation. RPI = corrected retic maturation time in days

Normal Adult Values Red Blood Cells Male: 4.7-6.1 x 106 /µl Female: 4.2-5.4 x 106 /µl Hemoglobin Male: 14-18 g/dl Female: 12-16 g/dl Hematocrit Male: 42-52% Female: 37-47% MCV Male: 80-94 fl Female: 81-99 fl MCH 27-31 pg MCHC 32-36 % Reticulocyte 0.5-1.5% RDW 11.5-14.5%