Exam 3 Material Flashcards
Identify three areas of red cell metabolism that are crucial for normal erythrocyte survival and function.
- RBC membrane
- Hemoglobin structure and function
- RBC metabolic pathways
Discuss the two major proteins of the red cell membrane, glycophorin and spectrin, according to:
a. Integral versus peripheral protein
b. Major functions for each
a. Integral protein: extends through the lipid bilayer and is permanently attached to the cell membrane
Peripheral protein: does not extend though the lipid bilayer, has temporary connections to the cell membrane, forms membrane cytoskeleton
b. Glycophorin: accounts for most of the membrane’s sialic acid – giving RBCs its negative charge
Spectrin: strengthens membrane (shape and stability), preserves deformability (pliability)
State the mechanism for producing each of the following types of poikilocytosis that are caused by structural membrane defects:
Acanthocytes
Bite cells
Spherocytes
Target cells:
Acanthocytes: an absence of low density lipoproteins (LDLs) leading to malabsorption of fats within the body (i.e. abetalipoproteinemia – acanthocytes)
Bite cells: a decrease in spectrin leading to less deformability – when attempting to pass thorough the spleen, it is very “slow” – the RE may try to phagocyte these cells leaving a portion of the RBC membrane removed
Spherocytes: a decrease in spectrin leading to less deformability – when attempting to pass thorough the spleen, it is very “slow” – the RE may try to phagocyte these cells leaving a reduce surface to volume ratio
Target cells: accumulation of cholesterol in RBC membrane leading to an increased surface area and decreased intracellular hemoglobin
State the protein carrier that delivers iron to the RBC membrane for hemoglobin synthesis.
Transferrin
List the two major tissues in the body where heme synthesis occurs.
- Erythroid marrow
- Liver
Diagram the sequence leading to heme synthesis … beginning with succinyl coenzyme A + glycine and ending with heme.
Succinyl coenzyme A + glycine to ALA to Porphobilinogen to Uroporphyrinogen to Coproporphyrinogen to Protoporphyrinogen IX to Protoporphyrin IX + Fe = Heme
Describe the chemical structure of heme.
Porphyrin is made up of four (4) five-member rings bound by methane bridges – the arrangement of the nitrogen atoms allows it to chelate metal atoms (i.e. iron)
Explain the reason why a patient with lead poisoning presents with “ringed sideroblasts”.
Lead damages one or more of the enzymes involved in heme synthesis – it blocks the incorporation of iron into the molecule leading to iron buildup in the mitochondria causing the “ringed sideroblasts”
Explain the reason why a freshly voided urine from a patient with a porphyria may not be red.
Porphyrin becomes oxidized from porphyrinogen, which is colorless – it oxidizes with exposure to air or acids – this process can take time
List three hemoglobins that are found exclusively in the embryo.
- Gower 1: Zeta2 – Epislon2
- Gower 2: Alpha2 – Epislon2
- Portland: Zeta2 – Gamma2 or Zeta2 - Alpha2
State the globin chain composition and percentages for each of the three normal adult hemoglobins.
- Hemoglobin A: Alpha2 – Beta2 (>95%)
- Hemoglobin A2: Alpha2 – Delta2 (1.5-3.0%)
- Hemoglobin F: Alpha2 – Gamma2 (~ 2%)
Characterize the oxygen affinity of the relaxed (R) form and the tense (T) form of the hemoglobin molecule.
Relaxed form (R): when hemoglobin has an affinity and readily binds to oxygen via ALL of the iron molecules (oxyhemoglobin – arterial blood)
Tense form (T): when hemoglobin has a lower affinity and readily unloads the oxygen via ALL of the iron molecules – binding of 2,3 DPG occurs (deoxyhemoglobin – venous blood)
Explain the relationship between pO2 of the surrounding medium and the percent of oxygen saturation of hemoglobin as depicted by an oxygen dissociation curve, including the effects of the following:
Hemoglobin’s affinity for oxygen based on its location and condition(s) in/of the body
pH: in the tissues – is decreased due to uptake of CO2, etc.
in the lungs – is increased due to expulsion of CO2
2,3 DPG levels: in the tissues – increased (O2 being squeezed out)
in the lungs – decreased (relaxed form of Hgb)
Temperature: in the tissues – increased (i.e. fever)
in the lungs – decreased
Differentiate “shift-to-the right” and “shift-to-the left” in relation to the hemoglobin-oxygen dissociation curve.
“Shift-to-the right:” favors the release of oxygen; therefore, lowering the affinity of hemoglobin for oxygen
“Shift-to-the left:” favors the uptake of oxygen; therefore increasing the affinity of hemoglobin for oxygen
List three abnormal hemoglobins that are unable to transport or deliver oxygen.
- Carboxyhemoglobin
- Methemoglobin
- Sulhemoglobin
State the main source of ATP production in the mature RBC.
Anaerobic breakdown of glucose
Name the metabolic pathway that generates most of the red cell’s ATP.
Embden-Meyerhof
State the major function for each of the following red cell metabolic pathways:
Embden-Meyerhof Pathway
Hexose Monophosphate Shunt
Methemoglobin Reductase Pathway
Leubering-Rapaport Shunt
Embden-Meyerhof Pathway
90% of the energy needed for the RBC is generated via this pathway – it produces two (2) molecules of ATP, the majority of glucose production and utilization
Hexose Monophosphate Shunt
5-10% glucose utilization (aerobically), protects against hydrogen peroxide which denatures hemoglobin (inherited defect: G-6-PD deficiency)
Methemoglobin Reductase Pathway
Maintains iron in the ferrous (2+) state
Leubering-Rapaport Shunt
Synthesis of 2,3 DPG – profound effect on hemoglobin’s affinity for oxygen, its stores can serve for additional ATP generation
State the changes in the red cell leading to its demise at 120 days.
As enzymes decrease, RBCs lose production of energy and deformability and no longer transverse through the microvasculature
Compare and contrast the steps involved in the extravascular versus intravascular breakdown of senescent RBCs.
Extravascular:
- RES cells phagocyte RBCs
- Iron is transported back to BM via transferrin
- Globin is return to AA pool
- Protophorphyrin ring dissembled – biliverdin converted to bilirubin
- Bilrubin is coupled to albumin and transported to liver
- Bilirubin converted to urobilinogen and excretedIntravascular:
- RBCs break in the lumen of vessel
- Haptoglobin picks up the free Hgb
- Hapto-Hgb complex goes to the liver for further metabolism – follows the same process as extravascular
State the characteristic level (decreased, normal, or increased) of haptoglobin in the presence of intravascular hemolysis.
Decreased – during intravascular hemolysis, destruction of RBCs are occurring within the blood vessel leaving haptoglobin to the vessel to pick-up the free hemoglobin – it would lower the plasma haptoglobin levels that would lead to hemoglobinemia or hemoglobinuria
State the protein carrier for the following:
Bilirubin
Hemoglobin
Iron
Bilirubin: albumin
Hemoglobin: haptoglobin
Iron: transferrin
List two general causes for anemia.
• Increased loss of RBCs (hemorrhage or hemolysis)
• Decreased production of RBCs (in the BM)
Describe six (general) clinical symptoms of anemia.
• Pallor
• Lightheadedness
• Muscle weakness
• Vertigo
• General lethargy
• Dyspnea (shortness of breath)
• Tachycardia (increased heart rate)
Describe the characteristic results you would find in the workup of an anemic patient with regard to the following laboratory tests:
Cell profile
RBC indices (microcytic-hypochromic anemia)
RBC indices (macrocytic anemia)
RBC indices (normocytic-normochromic anemia)
Reticulocyte count (aplastic anemia)
Reticulocyte count (extracorpuscular hemolytic anemia)
Cell profile: decreased RBC count and/or decreased hemoglobin
RBC indices (microcytic-hypochromic anemia): MCV< 80 fL, MCHC< 32 g/dL
RBC indices (macrocytic anemia): MCV> 100 fL
RBC indices (normocytic-normochromic anemia): MCV 80-100 fL, MCHC 32-36 g/dL
Reticulocyte count (aplastic anemia): decreased retic count
Reticulocyte count (extracorpuscular hemolytic anemia): increased retic count
Describe the characteristic RBC morphology you would find with regard to the following diseases/anemias:
Extracorpuscular hemolytic anemia
Hereditary spherocytosis
Liver disease
Pernicious anemia
Sickle cell anemia
Thalassemia
Hemoglobinopathy
Extracorpuscular hemolytic anemia: schistocytes and spherocytes
Hereditary spherocytosis: spherocytes
Liver disease: round macrocytes, targets, stomatocytes, spur cells
Pernicious anemia: oval macrocytes and teardrops
Sickle cell anemia: sickle cells
Thalassemia: M/H w/marked morphology and basophilic stippling
Hemoglobinopathy: “targets plus…” – sickle cells, C crystals, SC crystals
List the anemias found under the following “morphologic classification of anemias” categories:
Microcytic-hypochromic (list four)
Macrocytic (list two)
Normocytic-normochromic (list three)
Microcytic-hypochromic (list four)
• Iron Deficiency Anemia
• Anemia of Chronic Inflammation (Disease)
• Sideroblastic Anemia
• Thalassemias
Macrocytic (list two)
• Non-megaloblastic Anemia
• Megaloblastic Anemia
Normocytic-normochromic (list three)
• Aplastic Anemia
• Hemoglobinpathies
• Hemolytic Anemias (other than hemoglobinopathies)
State three criteria for accepting a CBC profile.
• H & H in balance
• MCHC < 37
• Make sure results make sense!!
State the primary function of iron in the body.
Oxygen transport
State the six iron compartments of the body (from largest to smallest).
• Hemoglobin
• Storage
• Myoglobin
• Labile Pool
• Tissue Iron Department
• Transport Compartment
List four factors that influence iron absorption.
• Amount and type of iron accessible from food
• Functional state of GI mucosa and pancreas
• Current iron stores
• Erythropoietic needs
List three conditions that result in an increased need for iron.
• Growth periods
• Blood loss
• Diversion of iron to the fetus
Name the anatomic site at which iron is absorbed most efficiently.
Duodenum
State the function of transferrin.
Iron transport protein
Name the organelle that contains iron in the erythrocyte precursors.
Mitochondria
Describe what is being measured for each of the following laboratory determinations:
Serum iron:
TIBC:
Serum ferritin:
BM macrophage iron:
BM sideroblasts:
ZPP:
Serum iron: amount of iron (bound to transferrin) in the serum/plasma
TIBC: amount of iron that transferrin can bind
Serum ferritin: the amount of iron located in the body’s storage
BM macrophage iron: iron held by the RE cells in the erythroblastic island that is used to supply the developing RBC precursors in the BM
BM sideroblasts: nRBCs in the BM that contain iron
ZPP: insufficient iron availability to developing nRBCs – erythrocyte protoporphyrin accumulates in the cell
State the relationship between serum ferritin levels and bone marrow iron stores in a healthy individual.
In a healthy person, serum ferritin is equivalent to the body’s storage of iron, in BM
Describe the peripheral smear RBC morphology that would prompt the ordering of iron studies.
Hypochromia, Microcytes, Aniso, some poik, variable
Discuss, in detail, iron deficiency anemia, including:
Causes (infants vs. adults)
Clinical signs and symptoms
RBC count and/or HGB:
PLT count:
RBC morphology
MCV:
MCHC:
RDW:
Reticulocyte count:
Treatment:
Infants: milk anemia – being fed cow’s milk can make it more difficult to absorb iron
Adults: poor diet, GI bleeds, malabsorption, mental blood loss, pregnancy
Pallor, fatigue, lethargy, SOB – Koilonychia (an abnormal thinness and concavity of the fingernails), heart murmur, peculiar cravings
RBC count and/or HGB: decreased
PLT count: increased
RBC morphology: Hypochromia, Microcytes, Aniso, some poik, variable
MCV: decreased
MCHC: decreased
RDW: increased
Reticulocyte count: increased
Treatment: treat underlying cause, supplemental iron
Discuss the mechanism (pathology) for developing a hypochromic-microcytic anemia for each of the following conditions:
Iron deficiency anemia
Anemia of chronic inflammation (disease)
Sideroblastic anemia
Malabsorption, decreased dietary intake, and increase loss of iron leads to:
Decreased iron – decreased Hgb – hypochromia – extra cell divisions – microcytosis
BM macrophages fail to give up iron to the RBC precursors; therefore RBCs develop iron deficient
An accumulation of iron in the mitochondria of nRBCs that “gets trapped” – porphyria
Discuss the mechanism (pathology) for developing a hypochromic-microcytic anemia for each of the following conditions:
Iron deficiency anemia
Anemia of chronic inflammation (disease)
Sideroblastic anemia
Malabsorption, decreased dietary intake, and increase loss of iron leads to:
Decreased iron – decreased Hgb – hypochromia – extra cell divisions – microcytosis
BM macrophages fail to give up iron to the RBC precursors; therefore RBCs develop iron deficient
An accumulation of iron in the mitochondria of nRBCs that “gets trapped” – porphyria
Differentiate iron deficiency anemia, anemia of chronic inflammation (disease), and sideroblastic anemia according to the following iron studies:
Serum iron
Iron deficiency anemia: decreased
Anemia of chronic inflammation (disease): decreased
Sideroblastic anemia: increased
TIBC
Iron deficiency anemia: increased
Anemia of chronic inflammation (disease): decreased
Sideroblastic anemia: decreased
Ferritin levels
Iron deficiency anemia: decreased
Anemia of chronic inflammation (disease): increased
Sideroblastic anemia: increased
BM macrophage iron
Iron deficiency anemia: decreased
Anemia of chronic inflammation (disease): increased
Sideroblastic anemia: increased
BM sideroblasts
Iron deficiency anemia: decreased
Anemia of chronic inflammation (disease): decreased
Sideroblastic anemia: increased
Serum iron
Iron deficiency anemia: decreased
Anemia of chronic inflammation (disease): decreased
Sideroblastic anemia: increased
TIBC
Iron deficiency anemia: increased
Anemia of chronic inflammation (disease): decreased
Sideroblastic anemia: decreased
Ferritin levels
Iron deficiency anemia: decreased
Anemia of chronic inflammation (disease): increased
Sideroblastic anemia: increased
BM macrophage iron
Iron deficiency anemia: decreased
Anemia of chronic inflammation (disease): increased
Sideroblastic anemia: increased
BM sideroblasts
Iron deficiency anemia: decreased
Anemia of chronic inflammation (disease): decreased
Sideroblastic anemia: increased
State the reason why long-term iron therapy should not be given to a patient with anemia of chronic inflammation (disease).
The amount of iron isn’t the issue – it’s the release of iron made available to the cells
Discuss the reason for the presence of “ringed sideroblasts” upon bone marrow iron exam of a patient with lead poisoning.
Excess iron-laden in the mitochondria form a ring around the nucleus
State the characteristic RBC histogram appearance one would expect to see in a patient with sideroblastic anemia, especially a hereditary form.
Two (2) peaks due to the presence of two RBC populations
Discuss hereditary hemochromatosis according to complications and treatment.
Iron overload – major concern is location of iron deposits – occurring in certain organs of the body can initiate a fibrotic response
State the hemoglobin molecule defect found in a thalassemia.
Defect in the rate of synthesis of one or more of the globin chains
Describe the suspected reasoning for the (same) geographic distribution pattern that coincide with the incidence of malaria and the heterozygous state(s) of the thalassemia syndromes.
Being heterozygous is advantageous against malaria – having one altered Hgb gene makes infections with Malaria less likely, but sickle cell and thalassemias can occur within the same individual
State the globin chain composition and percentages of the three normal adult hemoglobins.
• Hemoglobin A: Alpha2 – Beta2 (>95%)
• Hemoglobin A2: Alpha2 – Delta2 (1.5-3.0%)
• Hemoglobin F: Alpha2 – Gamma2 (~ 2%)
Describe what is meant by the following nomenclatures as they pertain to the production of globin chains:
β0 thalassemia:
β+ thalassemia:
α0 thalassemia:
β0 thalassemia: beta chains ARE NOT being formed
β+ thalassemia: decreased production of beta chains
α0 thalassemia: alpha chains ARE NOT being formed
List the four genetic possibilities that may occur with an alpha thalassemia.
• No alpha chain production
• One alpha chain functioning – 3 deleted
• Two alpha chain functioning – 2 deleted
• Three alpha chain functioning – 1 deleted
Discuss, in detail, Beta Thalassemia Major, including:
Pathology
Ethnic distribution
Clinical features and course of disease
CBC results
RBC morphology
Retic count
BM exam
Hemoglobin electrophoretic pattern
Treatment
Pathology
Reduced and/or absent beta chain production – alpha chain synthesis occurs at a normal rate creating an imbalance and leading to precipitation of excess alpha chains resulting in Heinz bodies
Ethnic distribution
Mediterranean area and SE Asia
Clinical features and course of disease
• Onset in early childhood
• Severe hemolytic anemia
• “too many RBCs for Hgb”
• Shorten life span
CBC results
“Too many RBCs for the Hgb”
RBC morphology
Mk’d aniso, poly, hypo, and micro
Mk’d poik w/ targets, schistos, spheres, tears
Inclusions
nRBCs
Retic count
Increased
BM exam
Marked erythroid hyperplasia (a lot of immature RBCs)
Increase in iron stores
Hemoglobin electrophoretic pattern
40-60% F
Increased A2
Decreased A (or absent)
F > A2 – has an greater affinity for oxygen so we observe an increase F before A2
A2/C, S, F, A (shortest to longest distance)
Treatment
Regular transfusions
Iron chelation therapy
Splenectomy
Diet restrictions
Vitamin B & Folate supplementation
Discuss the two mechanisms responsible for the early RBC destruction (hemolysis) as seen in Beta Thalassemia Major.
• Cells in the BM w/ Heinz bodies leads to ineffective erythropoiesis
• Cells in the circulation w/ Heinz bodies leads to intravascular hemolysis
Discuss the reason(s) why patients with Beta Thalassemia Major have the following findings: “hair-on-end” appearance on skull x-rays and Mongoloid appearance to face
Due to an increase in hematopoiesis that has caused an expansion of the BM
State the results of the following chemistry tests as expected during any hemolytic process… including Beta Thalassemia Major:
Plasma haptoglobin: decreased
Serum bilirubin: increased
Serum ferritin: increased
Serum iron: increased
Discuss, in detail, Beta Thalassemia Minor, including:
Pathology
Ethnic origin:
Clinical features and course of disease:
CBC results:
RBC morphology:
Retic count:
BM exam:
Hemoglobin electrophoretic pattern
Treatment:
Pathology: reduced rate of beta chain production
Ethnic origin: Mediterranean area, SE Asia, Black population of North America and West Africa
Clinical features and course of disease: mild, asymptomatic hemolytic anemia, slight splenomegaly, normal life span
CBC results: “Too many RBCs for the Hgb”
RBC morphology: Slt.-Mod for all morphology relative to Major (aniso, poly, hypo, and micro – poik w/ targets, schistos, spheres, tears – inclusions and nRBCs
Retic count: slightly increased
BM exam:
Mild – mod. erythroid hyperplasia (a lot of immature RBCs)
Increase in iron stores
Hemoglobin electrophoretic pattern
Hgb A predominates – increase in A2 (greater than %5) – increase in F (1-5%)
Treatment: Not usually required
Compare and contrast Beta Thalassemia Minor with Iron Deficiency Anemia according to the following parameters:
RBC count:
Beta Thalassemia Minor:
Iron Deficiency Anemia:
Hemoglobin value
Beta Thalassemia Minor:
Iron Deficiency Anemia:
Hgb A2 level
Beta Thalassemia Minor
Iron Deficiency Anemia
ZPP
Beta Thalassemia Minor:
Iron Deficiency Anemia:
RBC count:
Beta Thalassemia Minor: increased
Iron Deficiency Anemia: decreased
Hemoglobin value
Beta Thalassemia Minor: >10 g/dL
Iron Deficiency Anemia: <10 g/dL
Hgb A2 level
Beta Thalassemia Minor: >5%
Iron Deficiency Anemia: normal
ZPP
Beta Thalassemia Minor: normal
Iron Deficiency Anemia: increased
Discuss Hydrops Fetalis Syndrome according to:
Pathology of the hemoglobin molecule:
Globin chain makeup:
Ethnic distribution:
Compatibility with life:
Pathology of the hemoglobin molecule: no alpha chain production
Globin chain makeup: Bart’s = gamma4
Ethnic distribution: SE Asia & Filipino population
Compatibility with life: Death in utero/shortly after delivery
Discuss Hemoglobin H disease according to:
Pathology of the hemoglobin molecule
Globin chain makeup:
Unusual characteristic of Heinz bodies:
Pathology of the hemoglobin molecule: one functioning alpha chain
Globin chain makeup: Hgb H = beta4
Unusual characteristic of Heinz bodies: RBCs so full of Heinz bodies – “raspberry” appearance
Discuss Hemoglobin Lepore according to:
Pathology of the hemoglobin molecule:
Hemoglobins being produced in homozygous state:
Pathology of the hemoglobin molecule: fused delta and beta chain
Hemoglobins being produced in homozygous state: produces ~80% Hgb F and make a Lepore with the fused delta and beta chains ~20%
Describe the condition known as Hereditary Persistence of Hemoglobin F (HPFH).
Persistence of fetal hemoglobin in adult life
Homozygous state (rare) – 100% Hemoglobin F
Heterozygous – A > Hgb F (15-30%)
Discuss the Kleihauer-Betke stain according to:
Principle:
Normal values:
Staining pattern with HPFH:
Staining pattern with hemoglobinopathies (other than HPFH):
Appearance of hemoglobin A (adult) cells on smear:
Appearance of hemoglobin F (fetal) cells on smear:
Principle: assess the distribution of Hgb F in the RBC
Normal values: adults < 0.01%,
Staining pattern with HPFH: consistently dark pink
Staining pattern with hemoglobinopathies (other than HPFH): “speckled”
Appearance of hemoglobin A (adult) cells on smear: “Ghost cells”
Appearance of hemoglobin F (fetal) cells on smear: Dark pink
Describe Heinz bodies with regard to:
Three supravital stain used to detect them:
Appearance on Wright stain:
Composition in: homozygous beta thalassemia:
homozygous alpha0 thalassemia:
hemoglobin H disease:
Three supravital stain used to detect them: crystal violet, new methylene blue, brilliant cresyl blue
Appearance on Wright stain: CAN NOT SEE
Composition in: homozygous beta thalassemia: precipitated Hgb – all alpha globins
homozygous alpha0 thalassemia: precipitated Hgb – all gamma globins
hemoglobin H disease: precipitated Hgb – all beta globins
