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OMS II BECOM Exam 1 > Pathology of red cell disorders - Zaloga > Flashcards

Pathology of red cell disorders - Zaloga Flashcards

1
Q

anemia

A
  • reduction of total circulating red cell mass causing reduced O2 carrying capacity of blood –> hypoxia
  • diagnosed through hematocrit or Hb [] of blood
  • effects: fatigue, SOB, affects the heart, liver, and CNS
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2
Q

red cell indices

A
  • MCV = average volume of a RBC in sample
  • MCH = average content of Hb in a red cell sample
  • MCHC = average [] of Hb in a red cell sample
  • RDW = variation of RBCs in a sample
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3
Q

reticulocytes

A
  • immature RBCs released from the bone marrow

- high count –> marrow is being stimulated

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4
Q

microcytic anemias

A
  • Fe deficiency
  • anemia of chronic disease
  • sideroblastic
  • thalassemias
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5
Q

macrocytic anemias

A
  • vit. B12 or folate deficiency
  • liver disease
  • chemotherapy
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6
Q

Heinz bodies

A
  • unstable Hb in the cytoplasm

- can lead to thalassemias and HbH disease

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7
Q

megaloblastic anemias

A
  • type of macrocytic anemia
  • impairment of DNA synthesis –> ineffective hematopoiesis –> cells don’t divide & appear larger –> pancytopenia
  • Vit. B12 and folate deficiency –> cannot make thymidine
  • premature apoptosis in the marrow –> phagocytosed by Macs
  • large red cells due to RNA synthesis (can still make uridine)
  • immature nucleus but mature cytoplasm**
  • macrocytic RBCs, hypersegmented neutrophils**
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8
Q

normal B12 metabolism

A
  • requires intrinsic factor (made by parietal cells) for duodenum absorption
  • B12 binds to salivary haptocorrin –> pancreatic proteases release B12 in duodenum to bind to IF –> cubulin receptor in ileum for IF/B12 –> transform into transcobalamin II to travel in plasma to liver etc.
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9
Q

megaloblastic anemia - B12 deficiency

A
  • no reduced form of THF4 –> no thymidine
  • folate stuck in N5-methylTHF4 (methyl trap)
  • pathologic changes in nervous system (spinal cord) –> motor and sensory deficits**
  • usually no dietary insufficiency (long stores)**
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10
Q

how can you get B12 deficiency?

A
  • pernicious anemia** –> autoimmune gastritis that impairs intrinsic factor
  • autoreactive T cells against parietal cells** –> trigger autoantibodies
  • increased risk of gastric carcinoma
  • CNS deficits like demyelination of spinal cord –> paresthesia and ataxia
  • need to replace B12
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11
Q

megaloblastic anemia - folic acid deficiency

A
  • modest reserves –> deficiency faster than B12**
  • due to decreased intake or increased requirements –> pregnancy, infancy, age, hemolytic anemia
  • methotrexate can reduce THF4
  • no neurologic symptoms like B12**
  • make neurologic symptoms worse if already B12 deficient** (give B12 1st before folate treatment**)
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12
Q

microcytic anemias

A
  • Fe deficiency most common cause –> due to diet, impaired absorption, increased requirement, blood loss
  • no Fe –> no Hb –> no RBC
  • rule out GI cancer with chronic bleeding
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13
Q

Fe metabolism

A
  • absorbed in duodenum (after being reduced to Fe2+/ferrous by stomach acid)
  • stores increase –> absorption decreases
  • hepcidin (liver protein) regulates Fe transport from duodenum to blood –> inhibits ferroportin1 to prevent transport when Fe stores are full & vice versa**
  • Fe stores low –> hepcidin low**
  • transported by plasma transferrin** –> liver and marrow
  • stored as ferritin in marrow** (hemosiderin in excess) –> liver and mononuclear phagocytes (spleen, marrow)
  • ferritin in blood/tissue; hemosiderin in tissue only
  • used to make Hb of RBCs
  • degraded by Macs 120 days in spleen, liver, marrow
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14
Q

microcytic anemia - Fe deficiency

A
  • cause: impaired absorption, high requirement, blood loss
  • microcytic, hypochromic (less Hb)**
  • deplete Fe stores –> low serum Fe, ferritin, high transferrin
  • Hb and hematocrit are low
  • central pallor enlarged
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15
Q

microcytic anemia - thalassemia syndrome

A
  • causes hemolytic anemia
  • gene deletion and mutation –> unstable Hb –> precipitate causing membrane damage –> anemia, hypoxia, hemolysis
  • HbA (a2b2), HbF (a2, gamma2)
  • unbalanced chains recognized in bone marrow and phagocytosed –> ineffective erythropoiesis
  • microcytic, hypochromic cells
  • target cells and fragmented cells; spleen removes inclusions
  • crew cut appearance on X rays**
  • splenomegaly (due to phagocytosis and extramedullary hematopoiesis)
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16
Q

alpha thalassemia syndrome

A
  • deficient alpha chains (deletions)
  • 4 genes, chromosome 16
  • less severe than beta thalassemia
  • unpaired beta globin chains form precipitates
  • abnormal pairing of beta and gamma chains
  • delete single alpha gene (silent carrier) –> asymptomatic –> slight microcytosis
  • 2 genes (alpha thalassemia trait) –> like beta thal. minor, minimal anemia
  • 3 genes (HbH from beta globin tetramers) –> hypoxia, inclusions, phagocytosis, severe anemia
  • 4 genes (hydrops fettles from gamma globin tetramers; Hb Barts) –> hypoxia, edema, hepatosplenomegaly
17
Q

beta thalassemia syndrome

A
  • deficient beta chains (mutations)
  • 2 gene, chromosome 11
  • B0 (absent beta globin synthesis), B+ (reduced synthesis)
  • unpaired alpha globin chains form precipitates, inclusions –> membrane damage
  • heterozygote (1 mutated gene) –> mild microcytic anemia (b thalassemia minor)
  • 2 mutated genes –> severe ineffective erythropoiesis, erythroid hyperplasia in marrow, extra medullary hematopoiesis, transfusion dependent (b thalassemia major)
  • rare combinations of gene mutations –> moderate anemia (b thalassemia intermedia)
18
Q

anemia of chronic disease

A
  • chronic inflammation –> IL-6 –> increased hepcidin production**
  • chronic anemia bc ferroportin1 is inhibited –> no Fe transport to blood (remains stored in Macs)
  • reduced proliferation of erythroid progenitors and Fe utilization
  • maybe protection to defend against infection
  • increased storage in marrow macrophages, high serum ferritin rules out Fe deficiency
19
Q

normocytic anemias - acute blood loss

A
  • loss of intravascular volume (ex. GI bleed) –> shock
  • interstitial fluid restores volume diluting hematocrit (value decreases)
  • low O2 –> EPo release from kidneys –> stimulate erythroid progenitors
  • leukocytosis due to adrenergic increase in WBCs –> toxic granulations and Dohl bodies
20
Q

hemolytic anemias

A
  • due to extravascular or intravascular hemolysis
  • destruction of red cells due to surface proteins or phagocytosis in macrophages
  • anemia if lifespan is <120 days
  • accumulate Fe and hemosiderin
  • increased EPO and serum bilirubin levels**
  • increased reticulocytes
  • extramedullary hematopoiesis if necessary
21
Q

extravascular hemolysis

A
  • premature red cell destruction by Macs in spleen, marrow, liver
  • treat with splenectomy
  • see anemia, jaundice, splenomegaly
22
Q

intravascular hemolysis

A
  • less common
  • due to mechanical injury (heart valve), complement (antibody mediated), parasites (malaria), and toxins
  • destroy RBCs within vessel
  • anemia, hemoglobinuria, hemoglobinemia, jaundice (no splenomegaly)
  • haptoglobin depleted after it binds Hb then degraded by Macs
23
Q

hemolytic anemia - trauma induced

A
  • normocytic
  • mostly due to cardiac valves prosthesis or microangiopathic hemolytic anemia (MAHA)**
  • MAHA seen with DIC, TTP, HUS, hypertension, SLE, and cancer
  • MAHA causes lesion and fibrous strands –> luminal narrowing –> produce schistocytes**
24
Q

hemolytic anemia - hereditary spherocytosis

A
  • normocytic, autosomal dominant
  • extravascular hemolysis
  • get anemia, splenomegaly, jaundice, bilirubin gallstones
  • defective RBC membrane proteins –> form spherocytes** becoming less deformable –> destroyed by spleen
  • anemia corrected with splenectomy
  • spherocytosis –> produce Howell-Jolley bodies (DNA fragments)**
  • cells swell/burst with osmotic lysis hypotonic solution**
25
Q

hemolytic anemia - sickle cell

A
  • normocytic
  • extravascular hemolysis
  • mutation of beta globin (glutamate –> valine) forming HbS
  • causes RBC distortion, anemia, microvascular obstruction, and ischemic tissue damage
  • heterozygote for HbS (sickle cell trait) –> protection against P. falciparum malaria**
  • pathology: cytosol converted to viscous gel –> needle like fibers in red cell from HbS
  • cells become dehydrated, rigid, non deformable, deoxygenated –> more sickling
  • form target cells, Howell-jolley Bodies, splenomegaly/infarction/autosplenectomy
  • acute chest syndrome**
  • aplastic crisis –> parvovirus B19 infection**
  • susceptible to encapsulated organisms (pneumonia and H. influenza)
26
Q

hemolytic anemia - G6PD deficiency

A
  • normocytic, X linked
  • intravascular hemolysis
  • deficiency in G6PD –> cannot make NADPH for GSH –> oxidative stress to older RBC
  • oxidative stress by: infection, antimalarials, sulfonamides, fava beans –> cross link globin chains and form Heinz bodies** (remnants of precipitated Hb)
  • spleen degrades RBCs that have oxidants –> produce bite cells**
27
Q

hemolytic anemia - hemoglobin C (HbC)

A
  • normocytic
  • extravascular hemolysis
  • B globin mutation (glutamate –> lysine)**
  • sickling due to HbSC is milder than sickle cell disease
  • target cells on histo**
28
Q

hemolytic anemia - Paroxysmal nocturnal hemoglobinuria (PNH)

A
  • normocytic, X linked disease of HSC origin
  • intravascular hemolysis
  • mutations in PIGA gene of GPI anchor proteins**
  • absence of GPI anchor proteins, CD55, and CD59** –> uncontrolled complement activation (C5b-C9)**
  • causes hemolyis, thrombosis, and cytopenias
  • occurs at night due to decrease in blood pH activating complement
  • thrombosis leading cause of death**
29
Q

hemolytic anemia - immune hemolytic anemia (IHA)

A
  • normocytic
  • intravascular hemolysis
  • antibodies bind to RBCs –> premature destruction
  • IgM antibodies agglutinate cells
  • indirect (Coombs) antiglobulin test –> detect antibody in patient’s serum**
  • direct (Coombs) antiglobulin test –> detects antibody attached to patient’s RBC –> agglutination if antibody is on surface
  • in autoimmune hemolytic anemia, there is alloantibody is against blood antigen that is not on RBC –> warm antibody type most common and is usually IgG extravascular hemolysis
30
Q

polycythemia

A
  • abnormally high red cell count that increases Hb levels
  • relative –> decreased volume (dehydration) concentrating the Hb
  • absolute –> increased RBC mass from gene mutation or increased EPO due to lung disease
  • polycythemia vera most common cause of primary polycythemia –> mutations lead to EPO independent growth of progenitor cells

OMS II BECOM Exam 1 (30 decks)

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