Diagnostic Approach To Anemia: Archana M Agarwal, M.D
Diagnostic Approach To Anemia: Archana M Agarwal, M.D
Diagnostic Approach To Anemia: Archana M Agarwal, M.D
Anemia
Archana M Agarwal, M.D.
Department of Pathology
University of Utah School of
Medicine
Outlin
e
• Basic hematological parameters
• Discuss types of anemia and their
clinical manifestations
• Talk about the relevant diagnostic tests
Basic hematologic lab
tests
• Complete blood count (CBC)
– Amount of hemoglobin
– Number, size, and shape of red blood cells (RBCs)
– Number of white blood cells (WBCs) and platelets
– +/- automated WBC differential
• Manual differential/manual peripheral smear review
• Abnormalities that fall outside of established parameters
result in manual review
Complete blood count
(CBC)
• Hemoglobin (g/dL) Amount of oxygen carrying protein
• Hematocrit (%) % of blood volume occupied by RBCs
• RBC count (M/uL) # of RBCs
• MCV (fL) mean cell volume
• MCH (pg) mean cell hemoglobin
• MCHC (g/dL) mean cell hemoglobin
c onc entratio
n red cell distribution width
• RDW (%) (K/ # of WBCs
•• WBC
Platelet c ount uL) # of platelets
(K/uL)
Measuring RBC parameters
• Hemoglobin (Hb)
– Measured directly as absorbance of cyanomethemoglobin
• Hematocrit (Hct)
– Measured by centrifugation; ratio of volume of RBCs to volume of whole
blood
– C an also calculate (MC V x RBC )
• MCV
– Measured by mean height of voltage pulses in an impedance counter
– C an also calculate (Hct / RBC)
• M CH = Hb / RBC
• MCHC = Hb / Hct
Definition of anemia
• From Greek meaning “without blood”
• Condition where capacity of blood to transport oxygen to
tissues is reduced
– Decreased hemoglobin, RBC count, and hematocrit
• Anemia is not a disease but a m anifestation of disease
• Treatment depends on discovering underlying cause
Evaluating anemia in the lab
Basic information
• Size of red blood cells: (small/ normal/ big)
• Abnormal cells on microscopic examination
• Status of leukocytes and platelets
• Reticulocyte count (ability of marrow to respond to anemia)
• Evidence of destruction (elevated LDH, indirect bilirubin)
A practical approach to anemia
Size of RBCs
– MCV (Mean Cell
Volume)
Microcytic < 80 fl
Normocytic 80-100 fl
Macrocytic > 100 fl
Differential diagnosis of microcytic anemia
• Macrocytic anemia
• Hypersegmentation of neutrophils
– Myelodysplastic Syndrome
Evaluation of Normocytic Anemia
• PB smear, reticuloc yte c ount
• Screen for liver, endocrine, renal disease
• Iron studies
• Bone marrow biopsy
Hemolytic Anemia
• Inherited hemolytic anemia
• Acquired hemolytic anemia
Hemolytic Anemia
• Inherited hemolytic anemia
– Membrane defects (eg. hereditary spherocytosis)
– Globin defects (eg. Sickle cell anemia)
– Metabolic disorders
• Glucose-6 phosphate deficiency
• Pyrimidine 5’-nucleotidase deficiency (basophilic stippling).
Hereditary Spherocytosis
• Most common hereditary hemolytic anemia
• Spherocytes--microcytic, abnormal osmotic fragility
• May have broad RDW, but normal to low MCV and usually
increased MCHC, depending on the degree of reticulocytosis
• Autosomal dominant inheritance (75%)
• Mutations in various structural membrane proteins
• “Cured” by splenectomy
Hereditary Spherocytosis
Sickle Cell Anemia
Diagnosis of
HS
• Peripheral blood smear- Spherocytes
• Osmotic fragility
– a laboratory test used in the diagnosis of HS, is sensitive but
not specific. The test measures the in vitro lysis of RBCs
suspended in solutions of decreasing osmolarity. Spherocytes
are characterized by membrane loss and less redundancy to
withstand
Osmotic Fragility
Test
100
80
% Hemolysis
60
40
20
0
0.3 0.4 0.5 0.6
NaCl (% of normal
saline)
Normal
HS
Diagnosis Discontinued!
• Flow cytometry
– Greater than 95% sensitive and specific for HS
– Labels patients RBC s with EMA (eosin-5-maleimide)
– EMA binds specifically with band 3 protein
– EMA binding is affected by all sorts of membrane
protein abnormalities, not just band 3 deficiency
Glucose-6-Phosphate Deficiency (G6PD)
• Catalyzes the initial step in the pentose phosphate pathway
• X-linked; more than 300 variants identified
• 130,000,000 probably carry a mutant gene
– Up to 20-30% of Africans
– Up to 35% in Sardinia
– Also seen in Asians
Glucose-6-Phosphate Deficiency (G6PD)
• Two types of hemolytic anemia
– Acute, acquired hemolytic anemia
• Associated with exposure to primaquine, sulfa drugs
– DIC
– Malignant hypertension
– Giant hemangiomas
– March hemoglobinuria
– Drugs (mitomycin-C)
Microangiopathic Hemolytic Anemia
(www.dcss.cs.amedd.army.mil)
Microangiopathic Hemolytic Anemia
• March hemoglobinuria
– Disorder of transient hemoglobinemia or hemoglobinuria
due to forceful contact of body with hard surface
– Reported in
• Prolonged marches
• Competitive running
• Conga drumming
• Karate
• Jack hammer operators
Hemolytic Anemia Associated With
Infection
• Clostridium sepsis: may be severe, overwhelming
– Urgent identification and treatment is necessary
– Lecithinase