1. Sequesters iron in storage sites which limits iron transfer and limits iron use 2. Suppresses EPO production

Red Blood Cell Disorders Flashcards by Miguel Santos

Definition of anemia

Decrease in Red Blood Cell Mass

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Microcytic, Normocytic, and Macrocytic Anemia MCV cutoff

Normo = 80 - 100

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Microcytic anemias have increased/decreased Hgb production

decreased. - maintains “concentration” of hgb by decreasing cell size

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Mechanism of anemia of chronic disease

Iron is stored in macrophage, not available for heme synthesis, leading to decreased Hgb and microcytic anemia

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Heme is composed of

Iron + Protoporphyrrin

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Low protoporphyrin leads to which anemia

Sideroblastic anemia

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4 Microcytic Anemias

IDA
Chronic Disease
Sideroblastic anemia
Thalassemia

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Most common type of anemia

IDA

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Iron absorption occurs in which part

Duodenum

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How is iron absorbed?

Iron absorbed
Ferroportin takes iron from enterocyte to blood
Transferrin transports iron and delivers to liver and bone marow
Iron is stored as ferritin bound in macrophage

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Measurements of iron status and function

Serum iron - iron in blood
TIBC - number of transferrin molecules present in blood
% Sat - number of bound Transferrin
Serum Ferritin

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Red cell morphology in early vs late iron deficiency

Early - Normocytic

Late - microcytic, hypochromic anemia

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3 clinical features of iron deficiency

Anemia
Koilonychia
Pica

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Iron deficiency anemia associated with esophageal web and atrophic glossitis, and presents with anemia, dysphagia, and beefy-red tongue

Plummer-Vinson syndrome

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Most common anemia in hospitalized patients

Anemia of chronic disease

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Acute phase reactant increased in anemia of chronic disease which sequesters iron

Hepcidin

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Effects of hepcidin

Sequesters iron in storage sites which limits iron transfer and limits iron use
Suppresses EPO production

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Logic behind hepcidin

Iron is used by bacteria - it is a protective mechanism for infection

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Protoporphyrin is produced from which part of Krebs Cycle?

Succinyl CoA

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Iron-laded mitochondria around nucleus of erythroid precursors seen in sideroblastic anemia

Ringed sideroblasts

No porphyrin so iron accumulates in mitochondria

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Prussian blue stain identifies which substance in the microscope?

Iron

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Rate limiting step in porphyrin synthesis, which is most common cause of congenital sideroblastic anemia

ALAS

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Acquired causes of sideroblastic anemia

Alcoholism
Lead poisoning
Vitamin B6 deficiency

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Decreased synthesis of globin chains of hemoglobin

Thalassemia

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Carriers of thalassemia are protected against which infection

Plasmodium falciparum

3 normal types of HgB

HbF (Fetal Hgb)(A2Y2) HbA (A2B2) HbA2 (A2d2)

How many alpha alleles (hgb) are present and in what chromosome are they located?

4 alleles | Chromosome 16

Number of gene deletions in alpha thalassemia and effect

1 gene - asymptomatic 2 genes - mild anemia, slightly increased RBC (cis deletion - risk of severe thalassemia in offspring) 3 genes - Hemoglobin H disease (beta chain tetramers damage RBC) (severe anemia) 4 genes - Hydrops fetalis (gamma chain tetramers, Hb Barts)

Number of beta genes and in what chromosome

2 beta genes | Chromosome 11

Alpha vs Beta thalassemia in terms of genetics

Alpha - deletions | Beta - mutations

Red blood cell with a stained area in the center, found in beta thalassemia

Target cell

What is increased in beta thalassemia minor

HbA2 HbA needs beta chain so this is very low/none

What is massive erythroid hyperplasia

Hematopoeisis occuring in skull and facial bones as a result of increased EPO

X ray finding in massive erythroid hyperplasia

Crew cut appearance Chipmunk like face

In megaloblastic anemia - why is there less cell divisions

Less DNA precursors

Function of Vitamin B 12 in DNA precursor synthesis

Takes methyl group from tetrahydrofolate so that it can participate in DNA synthesis, and transfers methyl to homocysteine to convert it to methionine

Macrocytic anemia causes not caused by B12 and folate

Alcoholism Liver Disease 5-FU use

Folate is absorbed in

Jejunum

Vitamin B 12 is absorbed in

Vit B 12 binds to intrinsic factor and absorbed in ileum

Autoimmune destruction of parietal cells in stomach, leading to intrinsic factor deficiency

Pernicious anemia

Parasite associated with vitamin B12 deficiency

Diphyllobothrium latum

Homocysteine and methylmalonic acid levels in Folate and B12 deficiency

homocysteine - both high | methylmalonic acid - normal in folate, high in B12

Major causes of normocytic anemia

Peripheral destruction | Underproduction

Reticulocyte morphology

larger cells with bluish cytoplasm - residual RNA

How to differentiate normocytic anemia etiology based on retic count

> 3% = peripheral destruction (hemolytic anemia) | <3% = marrow problem, underproduction

Extravascular hemolysis involves destruction by>

Reticuloendothelial system (spleen, macrophages)

Unconjugated bilirubin from hemolysis comes from ____ and is transported bound to ____

Protoporphyrrin albumin

What molecule binds hemoglobin which escaped from RBC in intravascular hemolysis

Haptoglobin it takes it to spleen

Pathophysio of hemosiderinuria

Hemoglobin is absorbed in renal tubular cells, then iron accumulates, and the cells are sloughedo off in urine

RBC defect where cytoskeleton is not tethered to the cell membrane due to defect in tethering proteins ankyrin, spectrin, and band 3.1

Hereditary Spherocytosis

Cause of anemia in hereditary spherocytosis

Cells more easily consumed by spleen due to shape, more hemolysis

CBC parameters increased in hereditary spherocytosis

Increased RDW, MCHC

Increased risk of aplastic crisis with which infection in erythroblasts

Parvovirus B19

Diagnostic Test for hereditary spherocytosis

Osmotic fragility test - cell is round, so when water comes in, it bursts easity

Treatment for Hereditary Spherocytosis

Splenectomy

Peripheral blood smear feature of Hereditary Spherocytosis post splenectomy

Howell-Jolly bodies - DNA fragments unremoved by missing spleen

Type of mutation in Sickle Cell Anemia

Autosomal Recessive

Amino acid change in sickle cell anemia

Glutamic acid to Valine

Primary hemoglobin present in sickle cell anemia

HbS - which aggregate into needle like structure when polymerized

Factors which increase/protect against sickling

Increase - hypoxemia, Dehydration, Acidosis | Decrease - HbF (why it doesnt present until 6mo), Hydroxyurea

Effect of repeated sickling

RBC damage - hemolysis, irreversible sickling leading to vasoocclusion

Common presenting sign of sickle cell disease in infants | above 6 months

Dactylitis

Sickle Cell trait patients do not have sickle cells, except in which organ

Renal Medulla

Laboratory test for Sickle Cell Disease and Trait

Metabisulfite screen: any amount of HbS will cause cell to sickle Hemoglobin Electrophoresis: confirms presence and amount of HbS

In Hemoglobin C, what is the protein change in hemoglobin?

Glutamic Acid to Lysine (Ly-C-ine)

Peripheral blood smear feature of Hemoglobin C

Hemoglobin C crystal

Acquired defect in myeloid stem cell leading to absent GPI making it susceptible to complement

Paroxysmal Nocturnal Hemoglobinuria

Why does intravascular hemolysis occur at night in PNH

Mild respiratory acidosis from shallow breathing at night activates complement

Laboratory test for PNH

Screen - sucrose test Confirmatory - acidified serum test, flow cytometry

Main cause of death in PNH

Thrombosis from destroyed platelet fragments

G6PD deficiency is what type of mutation

X linked

Pathophysio of G6PD

Reduced half life of G6PD. G6PD is enzyme in reaction which produces NADPH, which is required to convert used glutathione back. Low NADPH makes patient susceptible to oxidative stress

Examples of oxidative stress in G6PD deficiency

Infections, drugs (primaquine, sulfa drugs, dapsone), fava beans

Precipitated hemoglobin presents as ____ (morphology), and the cells where this Hgb is removed are called ______

Heinz bodies Bite Cells

Antibody mediated IgG or IgM destruction of RBC

Immune hemolytic anemia

IgG mediated hemolytic anemia leads to (morphology)

Spherocytes

Red Blood Cell Disorders Flashcards

(76 cards)