Anemia Flashcards
1
Q
Hemoglobin Structure
A
Tetramer composed of two unlike pairs of globin polypeptide chains (one pair of alpha-globin and one pair of non-alpha globin)
2
Q
Oxygen in its Ferrous vs Ferric form
A
Ferrous = Fe+2 (reduced) BIND O2
Ferric = Fe+3 (oxidized) CAN’T bind O2
Iron is reduced from ferric to ferrous by Cytochrome Reductase
3
Q
Allostery of Hemoglobin
A
When O2 binds to hemoglobin at one site, hemoglobin changes in configuration, which alters the binding affinity of additional O2
4
Q
Taut form of Hemoglobin
A
Deoxygenated form, under conditions where oxygen concentration is low (none of the 4 binding sites are occupied). T-configuration is present due to inter- and intra-salt bonds, H-bonding, and hydrophobic interactions
5
Q
Relaxed form of Hemoglobin
A
Oxygenated form. As oxygen becomes more available, 1 oxygen binds, configuration changes and other sites have higher binding affinity. Breaking of salt bonds lead to R-conformation
6
Q
Neumonic for %oxygen saturation with various pO2
A
mmHg/%
30-60, 60-90, 40-75 (100-98)
7
Q
How does pH affect the hemoglobin dissociation curve?
A
Low pH = decreased O2 affinity = shift to right
High pH = increased O2 affinity = shift to left
Known as BOHR EFFECT
8
Q
How does CO2 concentration affect the hemoglobin dissociation curve
A
CO2 + H20»_space; carbonic acid»_space; bicarbonate and H+
This leads to a lower pH, initiating Bohr Effect. O2 will be unloaded in tissues with high metabolism (more CO2=more acidic=less O2 affinity)
9
Q
How does Temperature affect the hemoglobin dissociation curve?
A
Higher Temp = Lower O2 affinity
10
Q
How does 2,3-BPG concentration affect the hemoglobin dissociation curve?
A
Increase in BPG = Lower O2 affinity
BPG is the product of anaerobic glycolytic pathway
11
Q
Hemoglobin vs Myoglobin
A
Myoglobin is a MONOMER and cannot undergo allosteric regulation. Has very high O2 affinity at very low O2 concentrations. Good for STORAGE
12
Q
What are conditions that would create a Right-shift on hemoglobin dissociation curve?
A
Functional abnormal hemoglobin variants
Increase in BPG: High altitude, Pulmonary hypoxemia, Severe anemia, Congestive heart failure, Hepatic cirrhosis
13
Q
What conditions would create a Left-shift on hemoglobin dissociation curve?
A
Functionally abnormal hemoglobin variants
CO poisoning
Decrease in BPG: Septic shock, Severe acidosis, Blood transfusion of stored blood, BPG-mutase deficiency
14
Q
Alpha-like globin chains
A
4 gene copies on chromosome 16
15
Q
Beta-like globin chians
A
2 gene copies on chromosome 11
16
Q
Fetal Hemoglobin
A
Have distinct hemoglobin with high O2 affinity:
At 4-14 weeks gestation: Gower I, Gower II, Portland
At 8 weeks gestation: Fetal hemoglobin. Binds BPG poorly, putting the hemoglobin in a permanent relaxed state. Also increase in Bohr Effect
17
Q
Hemoglobin at birth
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65-95% HbF and 20% HbA
18
Q
Hemoglobin after age 5
A
96-97% HbA
2% HbA2
1% HbF
19
Q
HbA2
A
Functions much like HbA, has the same Bohr effect, same response to Bohr effect. Is more heat stable and has slightly higher O2 affinity
20
Q
Hemoglobin Variants
A
More than 500 identified, ~200 are clinically significant
Most common HbS, HbC, HbE. Can lead to unstable hemoglobins or with altered O2 affinity
21
Q
High Affinity Hemoglobin
A
Hemoglobin Chesapeake: single point mutation. Erythrocytosis because O2 delivery is reduced
22
Q
Low Affinity Hemoglobin
A
Presents with cyanosis and mild anemia
23
Q
Unstable Hemoglobin
A
Spontaneously denature, may or may not bind O2
Ex: Hemoglobin Zurich (single point mutation, increases O2 binding). Also Hemoglobin Koln (mutation in Beta-chein, increase O2 affinity. Mild anemia, reticulocytosis, splenomegaly). Finally, Hemoglobin Poole (mutation in gamma chain, infants with hemolytic anemia that resolves in a few months)
24
Q
Methemoglobinemia
A
Fe+3 (ferric) cannot carry oxygen. The curve shifts to the left and p50 drops. Can be acquired (drugs and chemicals) or genetic (homozygous, think of the inbred blue-skinned family in KY). No treatment is needed for genetic, only cosmetic. For acquired, the higher the methoglobin level the more severe the symptoms (above 70% not compatible with life.
25
CO poisoning
240x more affinity to hemoglobin than O2. Normally have 3% CO, smokers have 10-15%. Causes curve to shift left. Leads to headache, malaise, nausea, dizziness., coma, MI. NOT cyanotic, instead is "cherry red"
26
Basic definition of Anemia, and the measurements to define it
Insufficient red cell mass to adequately deliver oxygen to peripheral tissues. Measure Hemoglobin concentration, Hematocrit, RBC count. Values will differ based on age, gender and geography
27
Reticulocyte Count
Is the percentage of reticulocytes with 1,000 RBC are counted. An increase in RBC destruction (or loss of blood) will raise the Reticulocyte count
28
Know the chart of Anemia by heart, OK?
OK!
29
Symptoms of Anemia
Shortness of breath, fatigue, rapid heart rate, dizziness, pain with exercise, pallor
30
Where do you find iron in the body?
Most iron is in hemoglobin, but about 25% is stored in Ferritin and Hemosiderin
31
Fe solubility
More soluble at low pH.
| In aqueous solutions, forms insoluble hydroxides unless bound to protein (ie Heme)
32
Iron Absorption
Occurs in DUODENUM. Gastric pH maintains solubility until it reaches the duodenum. Enters duodenum as FERRIC ion and is concerted to FERROUS ion by surface reductase. Absorption controlled by intraluminal and extraluminal factors
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Intraluminal factors for Iron Absorption
```
Gastric factors (low pH, gastroferrin), Presence of proteins and AA, Vitamin C, Amount of iron ingested.
Phytates and oxalates DECREASE absorption
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34
Extraluminal factors for Iron Absorption
Increased erythropoietic activity will increase Fe absorption
35
Iron Cycle, Transport
Transferrin. Binds 2 mole Fe+3. High binding affinity. Binds specific receptors
36
Iron Cycle, Storage
Ferritin. Intracellular storage protein. Multimeric structure. Center contains ferric salts/protein molecules and up to 4500 atoms of Fe with are biologically available
37
Iron Cycle
Allows iron to be re-used, limiting the amount needed from diet. Absorbed through mucosal cell and binds to Transferrin. Goes to bone marrow, enters through clatherin-coated pits. Endosome become acidfied, releasing iron. Iron become incorporated to hemoglobin, RBC circulates for 120 days. RBC removed my macrophages in spleen, macrophages sequester iron in Ferritin iron stores. Iron stores can be released and rebound to Transferrin
38
Hepcidin
A 25aa peptide in liver produced in response to high iron intake and for inflammation/infection. Production reduced by anemia or hypoxia. LOW hepcidin=INCREASED iron absorption. Negative regulator of iron absorption. Can be implication for iron resistant iron deficiency anemia
39
Characteristics of Iron Deficiency
Decrease Hgb synthesis, Decrease cell proliferation. Anemia. Mild defect in muscular performance or neuropsych dysfunction. Ridges on nails. Dysphagia. Gastritis. Immune dysfunction.
40
Diagnosing Iron Deficiency
Decrease in O2 carrying capacity. Decrease reticulocyte production. Microcytosis (Decrease MCV). Hypochromia (Decrease MCHC). Wide range of cell size (Increase RDW). Low serum Fe, Low Ferritin. High Total Iron Binding Capacity
41
Ddx for Iron Deficiency
Anemia of chronic inflammation/infection
Anemia of chronic disease
Thalassemia
Sideroblastic anemias
42
Iron Overload
From high iron diet, high iron absorption, or repeat transfusions. Can cause organ damage (cardiac arrhythmia, cardiac failure, liver dysfunction/failure, diabetes). Treatment through iron chelators or therapeutic phlebotomy
43
Features of Anemia due to chronic infection/inflammation
Tumor Necrosis Factor decreases iron availability from stores and decreases EPO production. INF-beta inhibits erythropoiesis. Patient may have fever, arthritis, fatigue. Other symptoms present consistant with infection. Labs show mild-mod anemia. Normal ferritin stores, but DECREASE in serum Fe, TBIC, EPO for Hct, and retic count.
44
Features of Anemia due to Lead Intoxicaiton
Lead inhibits synthesis of protoporphyrin and enzyme that ligates iron to porphyrin ring. Patient may experience personality changes, irritability, headache, weakness, wt loss, abd pain, vomiting. Labs show mild-mod anemia, decrease retic count, basophilic stippling, concurrent iron deficiency, increase zinc protoporphyrin. Chelation therapy to relive lead toxicity
45
Features of Anemia due to Renal disease/failure
EPO cannot be produced. You wouldn't see anemia until kidney fnx is less that 40%, then you would wee mild-severe anemia. Normochromic/Normocytic. Decreased retic count, EPO and RBC production. Patient exhibits fatigue, pallor, low exercise tolerance, dyspnea, tachypnea. Treat with EPO, treat co-morbid conditions
46
Features of Anemia due to Thyroid problems
Hyper or hypo thyroid activity. Weight gain or loss, systemic nail, skin and hair changes. Labs show decreased retic count. HyPOthyroid: mild anemia, normochromic/normocytic. May be macro- or microcytic.
HyPERthyroid: normocytic, may be microcytic. Treatment with hormone replacement therapy
47
Features of Anemia due to Adrenal problems
Nausea, vomiting, dehydration, weakness, circulatory collapse. Labs show mild anemia, cells are normocytic. Treat with hormone replacement therapy
48
When do you use Transfusion in Anemia
Only transfuse when severity of anemia has resulted in severe cardiovascular decomposition
49
When do you use EPO to treat Anemia?
When there is an absolute deficiency or a decrease of this cytokine out of proportion to the hematocrit level and for which a response has been documented
50
Features of Sideroblastic Anemia
Impaired production of protoporphyrin or incorporation of iron. Iron accumulates in mitochondria. Inherited or acquired. Variabled anemia, hypochromia and microcytosis
51
Protoporphyrin
A derivative of hemoglobin. Formed from heme by deletion of an atom of iron
52
Microcytic
RBC are small
53
Macrocytic
RBC are large
54
Normocytic
RBC are of normal size
55
Features of Low Affinity Hemoglobin Disease
Decreased affinity for oxygen. Shift of oxyhemoglobin dissociation. Patients have mild anemia.
56
Features of Protein Calorie Malnutrition Anemia
Variable anemia, usually normochromic and normocytic. Be concerned about other vitamin deficiencies
57
Importance of Folic Acid and Vitamin B12
Critical to support proliferation and maturation of all cells especially hematopoietic cells. Synthesis of methionine from homocysteine.
58
Deficiencies of Folic Acid and Vit B12
Deficiency leads to increase in cell size, arrest in S phase and then destruction, Results in ineffective erythropoiesis. MEGALOBLASTIC ANEMIA. Also associated with neutropenia and/or thrombocytopenia. Folic acid deficiency is rapid (alcohol, poor nutrition) while B12 deficiency develops slowly (due to malabsorption)
59
Where are Folate and Vit B12 Absorbed?
Folic Acid- JEJUNUM
| B12- ILEUM
60
Sources and Storage of Folate
Found widespread in food. Breastmild sufficient for infants. Once absorbed, is hydrolyzed, reduced and methylated before distribution to tissues or liver for storage. Undergoes enterohepatic circulation
61
Sources and Storage of Vit B12
Comes from food, originally synthesized by bacteria and algae and works its way up the food chain through eggs and meat (NO plants). Once ingested, released by stomach acid. Instrinsic Factor (gastric parietal cells) is the protein carrier. B12 is stored in liver.
62
Findings in Peripheral Blood and Bone Marrow in a patient with B12 or Folate deficiency
Erythroid hyperplasia present. Macrocytosis, Hypersegmented nuclei or neutrophils, neutropenia, thrombocytopenia, Increase in Bilirubin. Increase in MCV. Low retic count
63
Causes of Vit B12 Deficiency
Autoimmune disease, IF deficiency (cannot absorb), malabsorption due to pancreatic insufficiency, bacterial overgrowth, parasites, or AIDS.
64
Diagnosis of Vit B12 Deficiency
Patient can exhibit sensory losses, ataxia, spasticity, cognitive or emotional change. Positive Babinski refelx. METHYLMALONIC ACID will be increased in B12 deficiency ONLY. Also do Schilling Test
65
Causes of Folate Deficiency
Inadequate dietary intake, malabsorption, errors in folate metabolism, increased folate demands (pregnancy, psoriais), alcohol consumption.
66
Diagnosis of Folate Deficiency
Serum cobalamin levels and serum red cell folate levels. Levels of plasma homocysteine.
67
Hemolysis
Decrease in red cell survival or increase in RBC turnover beyond standard norms. Two kinds: Intravascular and Extravascular
68
Intravascular Hemolysis
Turnover within the vascular space:
| Release hemoglobin into circulation >> dissociates into alpha/beta dimer >> binds to hemoglobin >> removed by liver
69
Extravascular Hemolysis
Most common, occurs in spleen. Ingestion and clearance by macrophages. Red cell ingested by macrophage >> heme separate from globin, iron removed and stored in ferritin and porphyrin ring converted to bilirubin which is released from cells. Bilirubin converted to urobilinogen (cycles between gut and liver or is excreted in urine)
70
What are the major hereditary and acquired causes of Hemolytic Anemia
Spherocytosis, G6PD deficiency, Pyruvate kinase deficiency, Autoimmune,
71
Hereditary Spherocytosis
Anemia, Jaundice, Splenomegaly. Responsive to removal of spleen (no spleen, no entrapment of cells!). Loss of membrane leads to microspherocyte. Defects in Spectrin, Ankyrin or Band 3.
72
Glucose-5-Phosphate Dehydrogenase (G6PD) Deficiency
X-linked Recessive. Inability to restore reduced glutathione. Under oxidative stress, denauted globin attaches to membrane (Heinz Bodies). RBC is less flexible, gets trapped in spleen. May have selective resistance to malaria!
73
Laboratory Features for Spheocytosis
Variation in Hct, Hgb. Increase in Retic count. Decrease in MCV. Increased osmotic fragility
74
Laboratory Features of G6PD Deficiency
Microspherocytes, Heinz Bodies, Blister or Bite Cells
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Autoimmune Hemolytic Anemia
Antibodies to universal RBC antigens can cause hemolyss. Can cause either intravascular or extravascular hemolysis.
Acute of chronic onset of anemia, jaundice, dark urine.
76
Warm Antibodies of Autoimmune Hemolytic Anemia
IgG binds the red cell with high affinity and have no complement activating capacity inciting the splenic macrophage to anti-body mediated phagocytosis through compliment receptors
77
Cold Antibodies of Autoimmune Hemolytic Anemia
IgG or IgM triansiently bind red cell membrane in cooler areas of the body. As they move back to central circulation they avidly activate complement and create holes in plasma membrane. When cells move centrally, antibody dissociates and complement is left to destroy the cell (intravascular hemolysis)
78
Laboratory findings of Autoimmune Hemolytic Anemia
Mild to sever decrease in Hgb. Increase in retics and bilirubin. Presence of DAT. May have spherocytes, bite cells or teardrop cells.
79
Osmotic Fragility Test
Used to diagnose Hemolytic Anemia. Measure the in vitro lysis of RBC suspended in solutions. Normal RBCs well in hypotonic solutions while Spherocytes lyse in solutions of higher osmolarity than normal RBCs
80
Sickle-Cell Disease
Autosomal recessive disorder of hemoglobin in which both Beta-globin genes are mutated, with AT LEAST ONE allele demonstrating the sickle-cell mutation (Beta6 Glu>>Val)
81
Sickle-Cell Trait
One gene has the sickle-cell mutation while the other is normal. Reduces morbidity and mortality of malaria. Also increases fertility because reduces malaria fever, saving the little spermies. Rare splenic infarc in white males at high altitude
82
Findings on CBC and Peripheral Blood Smear in patients with Sickle Cell Disease
Sickle cells,schistocytes (broken cells), Polychromasia, poikilocytosis, Howell-Jolly Bodies, Target Cells,
83
Polychromasia
Blue colored retics present in peripheral blood smear
84
Poikilocytosis
Shape of RBC varies in blood smear
85
Describe the major variants to Sickle-Cell Disease
Look at Chart in Notes!!
86
What is the process by which HgS causes sickling?
When oxygenated, RBC has normal shape. When deoxygenated, the sickle hemoglobin polymerizes into 14-hellical fibers which distort the shape. When reoxygenated, goes back to normal. After several rounds, the sickle-shaped is permanent, and is destroyed. Other hemoglobins interfere with the polymerization and lessons the sickling. Even without the sickling, cells with HgS are extra sticky and adhere to cells in microvasculature, leading to occlusion. The more sticky the cells, the more sick the person
87
Effects of SSD on Spleen
Chronic occlusion of spleen causes autoinfarction (often by age 5). Can also impair immune system, requiring prophylactic penicillin
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Effects of SSD on CNS
10% of children with SSD have large vessel stroke. Adults are more likely for hemorrhages
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Effects of SSD on Lungs
Damage to vessels increase pressure on pulmonary arteries. Puts strain on R. side of heart (30-40% of patients). Most common cause of death in adults with SSD
90
Effects of SSD on Kidney
Tubules damaged by chronic vaso-occlusion resulting in inability to concentrate urine to avoid dehydration
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Effects of SSD on Retina
Retinal vessel damage leading to retinal detachment and blindness
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Effects of SSD on Femoral/Humoral heads
Avascular necrosis leading to chronic pain
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Effects of SSD on Skin
Ulcers due to microvascular ischemia
94
Sickle-Cell Crisis
Under conditions of hypoxia, dehydration, inflammation, infection or other stresses. Sudden vaso-occlusion leads to pain crisis. Examples: Hand-foot swelling, Acute chest syndrome, Priapism (RBC trapped in penis), Bone infarction. Common cause of crisis in children is Parvovirus B19 aka Fifths Disease
95
Therapies for patients with SSD
Folic Acid for developmental delays
Penicillin for sepsis, spleen death
Bone Marrow Translplant- curative, but only 20% have donor
Hydroxyurea Therapy- oral chemotherapy induces HbF, which interferes with polymerization, improves anemia and reduces acute pain
Transfusion- reverses life-threatening processes, but can lead to iron overload
96
Two most severe Sickle-Cell Diseases
Sickle Cell Anemia (S + S)
| Sickle/B0-Thalassemia (S + B0)- No A is made
97
Two intermediate Sickle-Cell Diseases
Sickle /Hemoglobin C (S + C)
| Sickle/ B+ Thalassemia (S + B+) Some A is made
98
In addition to adhesion, what other Pathophysiological Mechanisms are at play in SSD?
Direct damage to endothelium- upregulation of adhesion molecules, exuberant repair mechanisms, and apoptosis.
Elevations of WBC, WBC adhesion to endothelium.
Retention of adhesion molecules on damage RBC membranes, especially reticulocytes
Sickle cells only live for 20 days
99
Thalassemia
Underproduction of a hemoglobin chain due to a variety of mutations that result in poor or absent function of globin gene. Imbalance of chains lead to free excess chains binding to RBC membrane, membrane oxidative injury, increased membrane rigidity, decreased membrane stability
100
Alpha Thalassemia
Alpha-globin is under produced due to an absence of 1+/4 genes that control production on chromosome 16
101
Beta Thalassemia
Beta-globin is under produced most often due to a point mutation which results in a dysfunctional gene on chromosome 11
102
Explain the genetics of Thalassemia major, intermedia, and minor
B-Thal Major (Cooleys)- 2 severely abnormal genes
B-Thal Intermedia- 2 mild-moderately abnormal genes
B-Thal Minor- 1 normal, 1 abnormal gene
103
HbEE disease
EBeta-Thalassemia. 2 Hb E genes. Mild anemia, Low MCV. Never needs transplant
104
Manifestations of Thalassemias
Underproduction of normal hemoglobin. Small RBS (Low MCV). Low Mean Hemoglobin Concentraion. Uniform RBCs (normal RDW). Compensatory increase in RBC- normal or high RBC number. Sombrero-shaped RBCs
105
Barts Thalassemia
- - / - a Moderate to severe Anemia
106
Clinical Manifestations of Thalassemias
Fragile RBC has a short half-life and is destroyed in marrow, so anemia may be present. Expanded bone marrow and extramedullary hematopoiesis (tries to make up for inadequate RBCs), Increased iron absorption, Delayed growth and development, Endocrinopathies, Pulmonary HTN
107
Geographic distribution of (- a / - a) Thalassemia
Africa
108
Geographic distribution of ( - -/ a a) Thalassemia
SE Asia (more Hydrops fetalis)
109
Treatments for Thalassemia
Transfusion (extreme), Increase HgF by Hydroxyurea, Bone marrow transplant
