Normocytic Anemia Flashcards
Cause of aplastic anemia
Bone marrow failure due to:
- Direct damage (toxic agents, radiation)
- Telomere shortening (Dyskeratosis congenita)
- Immune-mediated destruction (malaria)
- Fanconi’s (congenital)
What is Fanconi’s anemia ?
- X-linked
- fragile chromosomes
- predisposed to developing leukemia/ cancer
What is pure red cell aplasia ?
- severe decrease of ONLY erythroid precursors
- other features of bone marrow are normal
- acquired or congenital
Aplastic anemia: CBC results (HGB, HCT, RBC, Indices, WBC, PLT, RETIC)
HGB decreased
HCT decreased
PLT decreased
WBC decreased
RBC decreased
RETIC decreased
MCV normal or increased
MCH normal
MCHC normal
NOTE: PANCYTOPENIA DUE TO BONE MARROW FAILURE = all CELL LINES DECREASED
Aplastic anemia: BM (M:E, iron stores, characteristic morph)
- M:E; decreased to normal but
PANCYTOPENIA - Iron stores INCREASED
Why is aplastic anemia referred to as a “dry tap” during BM aspirates ?
Bone marrow failure = pancytopenia
What is hemolytic anemia ?
- intra or extravascular
- rate of RBC destruction is GREATER than rate of RBC production
Differentiate intrinsic HA vs extrinsic HA
Intrinsic: defect in RBC (membrane, enzymes, hemoglobinopathies, inherited)
Extrinsic: external agents target normal RBCs (immune-mediated, malaria, toxins, mechanical injury)
What are hemoglobinopathies ?
- qualitative or quantitative
- disorders involving hemoglobin
What are heinz bodies ?
- excess globin chains precipitated into cytoplasm
- viewed by supravital stains
Cause of Sickle Cell Anemia
- a.a. substitution
- glutamic acid (negative charge) at POSITION 6 is replaced with VALINE (neutral charge) = conformation change in Hgb
Why does Hgb S form stacks when it releases oxygen ?
Hgb S is hydrophobic
List 4 causes of polymerized Hgb
- Low oxygen
- Low pH
- Increased 2,3-BPG
- Cell dehydration
Why does Hgb S cause clinical complications ?
- oxidative damage to RBC membranes = adherence to capillary surfaces and RBC aggregation = activate coagulation
- blood becomes more viscous = decreased flow rate
- surrounding tissues do not get oxygen
- IVH and EVH due to distorted shape = splenomegaly = more susceptible to infections
Sickle cell Disease (% of HbA, HbA2, HbF, HbS)
HbA= NONE
HbA2= N or increased
HbF= <20%
HbS= 80%
Sickle cell Trait (% of HbA, HbA2, HbF, HbS)
HbA= >60%
HbA2= N or increased
HbF= <1%
HbS= <40%
Cause of HgC
- glutamic acid at POSITION 6 is replaced by LYSINE in BETA globulin chain
Which Hgb variant forms short and thick crystals under O2 ?
HgC for CRYSTALS
Cause and characteristics of HgE
- lysine is replaced at POSITION 26 with GLUTAMIC ACID in the BETA globin chain = 2+ net charge
- WILL NOT POLYMERIZE
- commonly inherited with other Hemoglobinopathies (Thalassemia, Hb S or HbSE)
Cause of Hgb M
- proximal/ distal histidine is replaced by TYROSINE = methemoglobin
- methemoglobin’s FERRIC IRON = ineffective oxygen transport
NOTE: HgM for METHEMOGLOBIN
Significance of G6PD enzyme
- In Embden-Meyerhof pathway (Hexose monophosphate shunt)
- prevents oxidative damage to RBCs
- reduces NADP to NADPH to breakdown H2O2 = H2O + O2
How does G6PD cause anemia ?
- Without G6PD in Hexose monophosphate shunt, H2O2 cannot be broken down
- H2O2 causes oxidative damage to proteins (ie. HEMOGLOBIN) = HEINZ BODIES are precipitated out globin chains
- increased removal of Heinz bodies by spleen = bite cells + shistocytes
PBS of patient with G6PD Deficiency
- Heinz bodies = precipitated Hgb damaged by H2O2
- Bite cells + Schistocytes = increased removal of Heinz bodies by spleen
How does Pyruvate Kinase Deficiency cause anemia ?
- PK is an enzyme in Embden-Meyerhof pathway required to produce ATP
- inadequate ATP = membrane becomes rigid and less deformable, water and potassium leak, and RBCs are removed prematurely (hemolysis)
Cause of hereditary elliptosis
Defective SPECTRIN and PROTEIN 4.1 GENES
NOTE: a SPECTRUM is shaped like an ELLIPTO
How does Hereditary elliptocytosis cause anemia ?
deformed RBCs become trapped in spleen = EVH HEMOLYSIS