Red Blood Cell Disorders Flashcards
Define anemia
Reduction in circulating red blood cell mass
What symptom does anemia present like?
Hypoxia
Is anemia of pregnancy actually anemia?
No, just increased plasma volume
Symptoms of hypoxia/anemia include? (4)
- Weakness/fatigue/dyspnea
- Pale conjunctiva and skin
- Headache and lightheadedness
- Angina
What measurements are used to determine RBC mass?
- RBC count
- Hemoglobin
- Hematocrit
How is anemia defined in terms of Hb?
Males: Less than 13.5
Females: Less than 12.5
How is anemia defined in terms of MCV?
Microcytic: Less than 80
Normocytic: 80-100
Macrocytic >100
Anemias due to red cell production decrease are due to what? (2)
- Hematopoietic cell damage
2. Deficiency of factors for heme synthesis of DNA synthesis
Anemias due to increased red cell loss are due to what? (2)
- External blood loss
2. Red cell destruction
What is acute posthemorrhagic anemia?
What are clinical symptoms similar to
Following acute blood loss, there may be no decrease in any RBC mass markers but an increase in platelet count.
Hypovolemia
What are the four microcytic anemias?
- Iron deficiency
- Anemia of chronic disease
- Sideroblastic anemia
- Thalassemias
Microcytic anemia has what MCV?
Less than 80
Microcytic anemias are simply the result of what?
Decreased production of hemoglobin
Why does the microcytosis occur in microcytic anemias?
Extra cellular divisions to make smaller cells with same hemoglobin concentration as normal RBC’s.
Hemoglobin is made of what?
Heme and globin
Heme is made of what?
Iron and protoporphyrin
A decrease in what substances will result in a microcytic anemia? (3)
- Globin
- Iron
- Protoporphyrin
What is the most common type of anemia?
Why?
Iron-deficiency anemia
Most common nutritional deficiency in the world.
Absorption of iron occurs where?
Duodenum
What are the two forms iron is absorbed in?
Which is absorbed more readily?
What are the transporters for each
- Heme form (from meat): Absorbed quicker
- Non heme form (from vegetables)
- Heme: Heme transporter
- Non-heme: DMT-1
What is the key regulatory step of iron absorption?
Will iron be transferred from enterocyte into the blood via ferroportin
What is the function of transferrin?
Transports iron in the blood and delivers it to the liver and bone macrophages for storage.
Stored intracellular iron is bound by what?
Purpose of this?
Ferritin
Prevent free radical formation
What is serum iron?
Measurement of iron in the blood
What is TIBC?
Total-iron binding capacity which is a measure of transferrin in blood
What is % saturation?
What is normal
Percentage of transferrin molecules that are bound by iron
33%
What is serum ferritin?
Measure of iron stored in macrophages and liver
Iron deficiency is usually caused by what two paths?
- Dietary lack of iron
2. Blood loss
Most common causes of blood loss leading lack of iron? 3
- Menorrhagia
- Peptic ulcer disease in males
- Bleeding GI lesions
What two types of GI lesions are seen causing iron deficiency?
What population demographic specifically?
- Colon polyps/carcinoma in the Western world
- Hookworms in developing world
Elderly
What populations see menorrhagia and peptic ulcer disease?
- Menorrhagia: Females between 20 and 50
2. Peptic ulcer: Males between 20 and 50
Dietary deficiency is seen in what 3 manifestations?
- Infants: Human milk has very low iron
- Children: Poor diet or grow quickly
- Pregnant mothers: Need more iron for baby and herself
What effect does gastrectomy have on iron absorption?
Stomach acid normally maintains iron in Fe2+ state which absorbs fast. Without stomach acid, iron is in Fe3+ state in GI tract.
What are the four stages of iron deficiency?
- Storage iron depleted: Low ferritin and high TIBC
- Serum iron depleted: Low serum iron & percent saturated
- Normocytic anemia: Make fewer normal RBC’s
- Microcytic anemia: Make smaller and fewer RBC’s
What are the clinical features of iron deficiency? 6
- Anemia
- Koilonychia
- Pica
- Pallor
- Fatigue
- Dyspnea on exertion
What is Plummer Vinson syndrome? 3
How does it present?
- Severe iron deficiency anemia
- Atrophic glossitis
- Esophageal web
- Anemia
- Dysphagia
- Beefy-red tongue
Lab findings of Iron-deficiency anemia?
- Appearance of RBC’s
- RDW
- Ferritin
- TIBC
- Serum Iron
- Percent saturated
- Free erythrocyte protoporphyrin (FEP)
- Hb
- Hematocrit
- RBC count
- Small hypochromic RBC’s
- Increased (some normo and some micro)
- Decreased
- Increased
- Decreased
- Decreased
- Increased
- Decreased
- Decreased
- Decreased
What is most sensitive diagnostic of iron-deficient anemia?
What is one negative?
Serum ferritin
Serum ferritin elevates in pro-inflammatory states
Where is iron in terms of chronology of heme synthesis?
Last step
How to differ between Iron-deficiency and anemia of chronic disease?
Anemia of chronic disease has a low TIBC compared to ID-A.
How to differ between Beta-thalassemia minor and ID-A?
Increased Hb A2 in Beta-thalaseemia minor
Treatment of ID-A?
Supplemental iron (Ferrous sulfate)
Anemia of chronic disease is secondary to what types of diseases? 2
- Chronic inflammation (arthritis, infection)
2. Cancer
Anemia of chronic disease is most common in what population of patients?
Hospitalized patients
Chronic inflammation results in production of what?
Specifically?
Production of acute-phase reactants
Hepcidin
What is the function of hepcidin?
Hepcidin sequesters iron in storage sites by limiting iron transfer from macrophages to erythroid precursors AND suppressing EPO production.
How does A-CD appear at first?
Then what does it become?
- Normochromic and normocytic
2. Hypochromic and microcytic
What are the lab findings in A-CD?
- Ferritin
- TIBC
- Serum iron
- % saturation
- FEP
- Increased
- Decreased
- Decreased serum iron
- Decreased
- Increased
Treatment of A-CD? (2)
- EPO for cancer patients
2. Auto-immune disease treatment for chronic inflammed patients
Sideroblastic anemia is due to what?
Defective protoporphyrin synthesis
What is the first reaction in heme synthesis?
What is the co-factor?
Aminolevulinic acid synthetase (ALAS) converts succinyl CoA to aminolevulinic acid (ALA)
Vitamin B12
What is the second reaction of heme synthesis?
Aminolevulinic acid dehydratase (ALAD) converts ALA to porphobilinogen
What is the final reaction of heme synthesis?
Where is this located?
Ferrochelatase attaches protoporphyrin to iron to make heme
Mitochondria
What is the rate limiting step of heme synthesis?
First reaction to make ALA
If proto-porphyrin is deficient what happens to iron?
How does this appear?
Remains trapped in mitochondria
These iron-laden mitochondria form a ring around nucleus in erythroid precursors that are called ringed sideroblasts
What is the congenital cause of sideroblastic anemia?
X-linked defect in ALAS enzyme
What are the three acquired causes of sideroblastic anemia?
Explain each
- Alcoholism: Mitochondrial poison
- Lead poisoning (Inhibits ALAD and ferrochelatase)
- B6 deficiency: Required cofactor for ALAS and is decreased when treated with isoniazid
Lab findings in sideroblastic anemia?
- Ferritin
- TIBC
- Serum iron
- % saturated
- Cell appearance
- Increased ferritin
- Decreased TIBC
- Increased serum iron
- Increased % saturated
- Ringed sideroblasts
Treatment for sideroblastic anemia?
Pyridoxine
Thalassemia is an anemia due to what?
Decreased synthesis of globin chains of hemoglobin
Why is there a decrease in globin chain synthesis in thalassemia?
Mutations in the genes for certain globin chains
Mutated carriers of thalassemia have protection against what?
Plasmodium falciparum malaria
Alpha thalassemia is due to what mutation?
Deletion in alpha-globin gene
How many alpha thalassemia genes are normally present?
4, 2 on each chromosome
One gene deletion of alpha-globin results in what?
Asymptomatic
Two genes deleted of alpha-globin results in what?
Mild anemia with elevated RBC count.
A cis-deletion of alpha-globin genes has an increased risk of what?
Severe thalassemia in offspring
Cis deletion of alpha globin is seen in what population?
Asians
Trans deletion of alpha globin gene is seen in what population?
Africans
Three alpha globin genes deleted results in what?
Severe anemia.
What type of hemoglobin dominates in 3 alpha gene deletions?
Tetramers of Beta chains (Hemoglobin H)
Hemoglobin H has what effect?
Damages RBC membranes
Four genes deleted usually results in what?
Death of fetus (hydrops fetalis)
What hemoglobin dominates in 4 alpha gene deletions?
Tetramers of gamma chains (Hemoglobin Barts)
Beta thalassemia is due to what mutation?
Point mutation in promoter or splicing sites.
What population usually has Beta thalassemia? 2
- Africans
2. Mediterranean descent
What are the locations of alpha and beta globin genes?
- Alpha = Chromosome 16
2. Beta = Chromosome 11
What is Beta thalassemia minor?
1 normal Beta gene
1 mutated Beta gene
How does beta-thalassemia minor present? 6
- Asymptomatic
- Increased RBC count
- Hypochromic microcytic anemia
- Increased in hemoglobin A2 and HbF
- Decrease in hemoglobin A
- Target cells
What is beta thalassemia major?
Homozygous mutated Beta globin genes
When do symptoms of beta-thalassemia present?
Several months after birth when HbF begins to decrease.
What forms in Beta thalassemia major?
What does this result in? (2)
Alpha tetramers
Ineffective erythropoiesis Extravascular hemolysis (spleen removes RBC's)
How does the bone marrow respond to beta thalassemia major?
What does this result in? (3)
Massive erythroid hyperplasia
- Hematopoiesis into skull (crewcut x-ray) and facial bones (chipmunk facies)
- Hepatosplenomegaly
- Risk of aplastic crisis with parvovirus B19
Chronic transfusions in Beta-thalassemia majorsometimes lead to what?
Secondary hemochromatosis (Extra iron in blood)
How does a smear in beta-thalassemia major appear?
Microcytic hypochromic RBC’s with target cells and nucleated red blood cells
How do hemoglobin concentrations change in beta-thalassemia major?
Elevated HbA2 and HbF
little or no HbA