Macrocytic Anemia

CLINICAL PATHOLOGY DEPARTMENTSCU

Macrocytic Anemia

Normal blood cells

Complete Blood Count (CBC)

Normal red blood cells

Definition

An (without) -emia (blood):

a reduction below normal in hemoglobin or red blood cell number

Symptoms and signs of Anemia

None if mildFatigueBreathlessnessDizzinesPale Skin & mucous membranesJaundice ( if hemolytic)Tachycardia

Differential Diagnosis Using MCV

Macrocytic anemias (MCV = 150 fl): > normal cells

Normocytic (MCV = 80-96 fl): cells are normal in volume

Microcytic anemias (MCV = 50 fl): cells are < normal

Macrocytic anemia

Defined as MCV > 100 femtolitersIdentified by peripheral blood smear or

automated RBC indices Smear is more sensitive in detecting early macrocytic

changes and small numbers of macrocytes Cell morphology can aid in determining etiology of

macrocytosis

Common Causes of Macrocytosis

cause % of casesAlcohol abuse 36%B12 or Folate deficiency 21%Chemotherapy or drugs 11%Hemolysis or bleeding 7%Liver disease 6%Primary bone marrow disorders 5%Hypothyroidism 5%Others 12%

Megaloblastic Anemia

Defective DNA synthesis leads to nuclear/cytoplasmic asynchrony

B12/folate deficiencyMacrocytic anemia with hypersegmented neutrophils

Megaloblastic Anemia

retarded DNA synthesis unimpaired RNA synthesis

BIG cells! immature nucleusmature cytoplasm

How is B12 involved?

B12 (and folate) are required for DNA synthesis.• Slowed DNA synthesis means big, immature nucleus• Cytoplasm (with RNA in it) matures just fine

B12 is also required for conversion of homocysteine to methionine• ↑ homocysteine = atherosclerosis!• ↓ methionine = subacute combined degeneration

Megaloblastic anemia

Megaloblastic anemia

Reticulocyte Count (In the Diagnosis of Anemia)

Useful in determining response and potential of bone marrow.

Reticulocytes are non-nucleated RBCs that still contain RNA.

Visualized by staining with supravital dyes, including new methylene blue or brilliant cresyl blue; RNA is precipitated as dye-protein complex.

Normal range is 0.5-2.0% of all erythrocytes. If bone marrow responding to anemia, should see

increases in retic count. Newborns have higher retic count than adults until

second or third week of life.

Retics Slide

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