RBC DISORDERS 2 Flashcards
Quantitative vs Qualitative
- Anemia
- blood loss
- decreased production
- increased destruction - Polycythemia
Quantitative
Quan vs Quali
- abnormal in morphology
- abnormal in function
- intracorpuscular/Inherent to red cells
Quali
Reduction, from baseline value of:
– total Red Blood Cells (RBCs)
– circulating Hemoglobin (Hb)
– amount of Hematocrit (Hct)
Anemia
Parameters of Anemia Adult Male RBC: Hematocrit: Hemoglobin:
Adult Female
RBC:
Hematocrit:
Hemoglobin:
Adult Male
RBC: 4.6 – 6.0 x 1012/L
Hematocrit: 40 – 50 % (0.40 – 0.50 L/L)
Hemoglobin: 14.0 – 18.0 g/dL (140 – 180 g/L)
Adult Female
RBC: 4.0 – 5.4 x 1012/L
Hematocrit: 35 – 49 % (0.35 – 0.49 L/L)
Hemoglobin: 12.0 – 15.0 g/dL (120 – 150 g/L)
Result of the compensatory mechanism to Anemia
Erythropoiesis (increased reticulocytes in the peripheral blood
• also known as Minkowski–Chauffard syndrome
• Intrinsic defect in the red blood cell membrane skeleton
• Inherited disorder:
– 75% - an autosomal dominant inheritance pattern
– Compound heterozygosity (inheritance of 2 different defect)
• Highest prevalence in Northern Europe – 1 in 5,000
- autosomanl dominant disorder
- characterized by 1. spherocytes, 2. splenomegaly, 3. familial occurence
HEREDITARY SPHEROCYTOSIS
Clinical manifestations:Hereditary Spherocytosis
- chronic anemia,
- splenomegaly,
- gallstones (bilirubin stones) ,
- aplastic crisis.
Defect in Hereditary Spherocytosis
Deficiency of Beta Spectrin or Ankyrin -> Loss of membrane -> becomes more spherical -> Destruction in Spleen
Laboratory of Hereditary Spherocytosis
- Those of chronic extravascular hemolysis
- Increased pigment catabolism
- Erythroid hyperplasia
- Reticulocytosis
- Direct antiglobulin test (DAT) – negative
- MCV normal; MCHC often increased
- OFT increased
- Red cells arte suspended in a series of tubes containing hypotonic solutions of NaCl varying from 0.9 to 0.0%, incubated at room temperature for 30 minutes, and centrifuged.
- cells with decreased surface/volume ration, have limited capacity to expand in hypotonic solutions, hence undergo lysis.
Osmotic Fragility Tests
- Sterile, defibrinated blood is incubated at 370C for 48 hours.
- Cells undergo series of changes —- become more spherocytic
Autohemolysis Tests
HEREDITARY SPHEROCYTOSIS
Clinical Features:
- Triggered by Acute parvovirus infection. Around 1-2 weeks
- Produced by intercurrent events (ie infectious mononucleosis) -> increased spleenic destruction.
- Aplastic Crises
- Hemolytic Crises
Tx for HEREDITARY SPHEROCYTOSIS
- Supportive
- Splenectomy
- is involved in the Hexose Monophosphate shunt/Pentose Phospate Pathway -> Reduction of oxidized form of glutathione/detoxifies accumulated peroxide.
- Recessive x-linked trait: Males > Females
- Variants that cause most of the clinically significant Hemolytic anemia:
1. G6PD- - 10% of Americal Blacks
2. G6PD Mediterranean – prevalent in the Middle East
• Protective against Plasmodium falciparum
Glucose-6-Phosphate Dehydrogenase
Triggers of hemolysis in GLUCOSE-6-PHOSPHATE DEHYDROGENASE DEFICIENCY
- Infections
- Viral hepatitis, Pneumonias, Typhoid fever - Drugs
- Anti-malarial drugs, Sulfonamides, Nitrofurantoin - Food – Fava beans
GLUCOSE-6-PHOSPHATE DEHYDROGENASE DEFICIENCY
Clinical Features:
Acute Hemolysis
Recovery phase:
Usually starts 2 to 3 days following exposure
- Characteristics
1. Anemia
2. Hemoglubinuria
3. Hemoglobinemia - No features related to chronic hemolysis (splenomegaly and cholelithiasis.
Recovery phase:
- Reticulocytosis
Detects deficiencies in the pentose phosphate pathway:
- Glucose-6-Phosphate
- Dehydrogenase deficiency
- Glutathione reductase
- Glutathione peroxidase
Ascorbate Cyanide Screening Test
Morphology of GLUCOSE-6-PHOSPHATE DEHYDROGENASE DEFICIENCY
- macrophages eat the red blood cells
- due to high level of oxidants -> cross-linking of reactive sulfhydryl groups of hemoglobin -> denatured hemoglobin
- bite cells
- Heinz bodies
• An inherited disease of the red blood cells that is common among blacks
• Affect the proteins inside the red blood cells - HEMOGLOBIN.
• Deoxygenated red blood undergo transformation from normal biconcave disk to sickle - shaped structure.
- sickling phenomenon is due to polymerization of sickle hemoglobin Hb S
-
SICKLE CELL DISEASE
- HB SS (α2βς2) - due to point mutation
- Valine is substituted for glutamic acid at the 6th position of β - globin chain.
Homozygous form
• Red blood cells sickle when O2 saturation is < 40%
Example: Unpressurized aircraft, Deep sea diving
• Does not affect life span of patient.
• Normal blood counts and morphology
• Does not require treatment
Heterozygous form - Hb AS
Major Pathologic Manifestations: Sicle Cell Disease
- Chronic hemolysis
- Microvascular occlusion
- Tissue damage
SICKLE CELL DISEASE Morphology:
- Peripheral blood picture
- Anemia -
- Increased polychromasia -
- Normoblast
- Target cells
- Howell - Jolly and Pappenheimer bodies
- Sickle cells
- Peripheral blood picture
- Anemia - usually normocytic normochromic
- Increased polychromasia - reticulocytosis
- Normoblast may be seen
- Numerous Target cells
- Howell - Jolly and Pappenheimer bodies
- Numerous Sickle cells
SICKLE CELL DISEASE Morphology:
Bone marrow
Bone marrow
- Normoblastic hyperplasia
- Increased Iron storage
Diagnose:
- Cellulose acetate electrophoresis at pH 8.6
- 35 - 45 % Hb S Normal Hb F
- 50 - 65 % Hb A Normal to slightly inc. Hb A2
Hemoglobin Electrophoresis
• Adding Sodium Metabisulfite to blood enhances deoxygenation and sickling of the red blood cell.
• Drawback:
1. Does not distinguish Hb AS from Hb SS and other Hb S syndromes.
2. Positive test may occur with other rare abnormal hemoglobin (Hb C Harlem and Hb I).
3. False negative test may occur if Hb S is less than 10% or there is inadequate deoxygenation.
Sickling Test – Metabisulfite
- Adding Sodium hydrosulfite results to lysis of RBC and reduction of Hb S.
- Polymers of Hb S obstruct light rays and produce opacity.
- Useful for screening
Solubility Test – Dithionate
- Increasing proportion of red blood cells lyse upon exposure to increasing hypo-osmotic saline solution.
- OFT usually decreased
- Not specific
Osmotic Fragility Test
SICKLE CELL DISEASE
Treatment:
- Symtomatic
- Pain Management - Narcotics
ex. Morphine and Hydromorphone
- Reduce number of “crises”
HYDROXYUREA (Charade) Exchange Transfusion - Bone marrow transplant
- the medical term for a deficiency in the number of red blood cells (anemia)
- Heterogenous group of heritable anemias that have in common quantitatively defective synthesis of either α or β chains of the normal hemoglobin A tetramer (α2β2)
- Originally observed in Italian and Greek coast.
- Also seen in the Mediterrenean basin, Middle East, Parts of Pakistan, India, Southeast Asia, Southern Part of USSR, China and Northern Regions of African continent.
- Most frequent in malaria epidemic areas.
THALASSEMIA
Alpha VS Beta Thalassemia
- deletions of alpha-globin gene
- symptoms can begin in fetal life
- complicated inheritance- 4 alpha genes
Alpha
Alpha VS Beta Thallasemia
- nonsense, splice and frameshift mutations in beta globin gene
- symptoms begin in infncy/childhood
- simple AR inheritance; genotype-phenotype correlation
Beta
β-THALASSEMIA
Molecular Pathogenesis:
Extremely heterozygous
- Most commonly by ____ on chromosome 11
- Less commonly ____ of part of the gene
- point mutation
- deletion
β-THALASSEMIA
Molecular Pathogenesis:
Categories
- βo mutations associated with ___ β-globin synthesis
- β+ mutations ___ but detectable βo sythesis
- absent
- reduced
Mechanism of Anemia (β-THALASSEMIA):
- Deficiet Hb A synthesis
- “Underhemoglobinization” microcytic hypochromic red cells with abnormal oxygen
transport capacity
- Diminished survival of red cells and their precursors - Ineffective erythropoiesis
- Extravascular Hemolysis
Manifestation of 1.Heterozygous β- Thalassemia/β- Thalassemia Minor/
Cooley’s Trait (β0/β or β+/β)
- Moderate reduction of Hb A (α2 β2)
- Increased Hb A2 (α2δ2)
Manifestation of Homozygous β -Thalassemia / β -Thalassemia Major/ Cooley’s Anemia (β0 /β0 or β+/ β+)
Normal or moderately increased Hb A2 (α2δ2)
* Increased Hb F (α2γ2)
β – Thalassemia Morhology: Peripheral Blood
- mild anemia with some hypochromia and microcytosis
- poikilocytosis
- basophilic stippling
- target cells
Heterozygous
β – Thalassemia Morhology: Peripheral Blood
- hypochromic and microcytic anemia
- marked anisocytosis and poikilocytosis
- target cells, ovalocytes, siderocytes, nucleated RBCs
- extreme normoblastosis
- cabot rings, howell-jolly bodies
Homozygous
β – Thalassemia Morhology: Bone Marrow
- Normoblastic hyperplasia and increased Iron storage
- Marked normoblastic hyperplasia, Increased Iron storage, Increased sideroblast, Normoblast with inclusions
- Heterozygous
- Homozygous
β – Thalassemia Morhology:
Heterozygous vs Homozygous:
Osmotic Fragility Test
Blood Indices
Increased Indirect Bilirubin
Heterozygous - Decreased OFT
- Increased RBC
- Decreased HCT and Hb
- Low MCH and MCV; N to Low MCHC
Homozygous - Increased OFT
- Severe derangement
Increased Indirect Bilirubin: ALL
β – Thalassemia Treatment:
Symtomatic
- Iron chelation
2. Transfusion therapy
- Reflects the failure of one or more of the four (4) α - gene loci on chromosome 16 to function. Histopathogenesis: - 80 % of cases reflect gene deletion - less commonly by point mutation
- Limited to the tropical and subtropical regions of the world.
- Carriers have been reported to resist infection by Plasmodium falciparum.
Alpha – Thalassemia
Alpha – Thalassemia Syndrome:
- Deletion of one (1) α gene or inactivation by point mutation.
- Hematologic parameters are normal.
- Infants have 1 to 2 % of total Hb is Hb Bart’s.
Silent Carrier State /α+ - Thalassemia or α- - Thalassemia 2 /(αα/α-)
Alpha – Thalassemia Syndrome:
- Deletion of two (2) gene 3 Molecular mechanisms:
a. Deletions - 17 different types
b. Truncation of chromosome 16
c. Removal of the key regulatory region HS 40 - Mild hemolytic anemia
- Infants have Hb Bart’s of no more than 5 %
α - Thalassemia Trait / α –Thalassemia Minor /α 0- Thalassemia or α+ -Thalassemia 1/(αα/– or α-/α-)
Alpha – Thalassemia Syndrome:
- 3 genes deleted
- Moderate hemolytic anemia with hypochromia and microcytosis.
- First year of life with up to 25 % Bart’s Hb
- Adult Hb A predom
Hemoglobin H Disease (α-/– or αα/– cs)
Alpha – Thalassemia Syndrome:
- Complete deletion of 4 genes
- Death in - utero or Hydrops fetalis
Bart’s Hemoglobin
Diagnosis - Alpha - Thalassemia
All forms of Thalassemia show:
- Hypochromic microcytic anemia
- Ineffective erytropoiesis
- Hemolysis
Diagnosis - Alpha - Thalassemia:
Hydrops with Bart’s Hb
- Marked anisocytosis and poikilocytosis
- Marked microcytosis and erythroblastosis
- Absent ABO and Rh incompatibility
- Alkaline Electrophoresis:
Large quantities of Hb Bart’s (γ4)
Some Hb H (β4)
Diagnosis - Alpha - Thalassemia:
Hemoglobin H Disease
- Blood
- Electrophoresis
- Blood: Decreased MCV and MCH
> Hypochromia, target cells and anisopoikilocytosis
> Reticulocytes usually 4 to 5 %
> Hb H precipitates (BCB)
> Heinz bodies
- Electrophoresis:
> Hb H (β4) accounts for 4 to 30 %
> Traces of Hb Bart’s (γ4)
