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SBL (Skin, Blood, Lymph) Exam 1 and 2 > Chapter 14: Red Blood Cells > Flashcards

Chapter 14: Red Blood Cells Flashcards

1
Q

What are the Mean Cell Volume, Mean Cell Hemoglobin, Mean Cell Hemoglobin Concentration, and Red Cell Distribution Width values?

A

MCV: average volume of red blood cells
- normal = 80-100

MCH: average mass of hemoglobin per RBC
- changes RBCs color

MCHC: average hemoglobin concentration in a given volume of RBCs

RDW: coefficient of variation of red blood cell volume

  • elevation –> reactive phenomenon in anemia
  • have FUNCTIONING marrow
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2
Q

What is hematocrit?

A

ratio of packed RBCs to total blood volume

approximately 3x the hemoglobin concentration

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3
Q

If a male or postmenopausal women is found to be chronically bleeding, what should it be assumed that patient has until proven otherwise?

A

Colon Cancer

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4
Q

What is Hemolytic Anemia and what does it look like morphologically? (3)

A

RBC lifespan less than 120 days, with inc. in EPO and accumulation of hemoglobin degradation products

Morph: inc. normoblast in marrow, reticulocytosis in peripheral blood, hemosiderosis

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5
Q

What is the difference between Extravascular and Intravascular Hematopoiesis?

A

EH: occurs in macrophages of spleen (predisposed by RBC injury)

  • anemia, splenomegaly, jaundice
  • splenectomy is often beneficial

IH: RBC rupture due to mechanical injury, complement, parasites, or toxins

  • hemoglobinuria, hemosiderinuria (NO splenomega)
  • markedly reduced serum haptoglobin (a2 globulin)
  • renal hemosiderosis

haptoglobin normally prevents hemoglobin excretion in urine

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6
Q

Hereditary Spherocytosis:

What is it, how is it inherited, and what is its pathogenesis?

A
  • defects of RBC membrane skeleton causing cells to become spheroid and less deformable
  • 75% autosomal dominant, mostly prevelant in Northern Europe
  • mutations of ankyrin, band 3, band 4.2, and spectrin (RBCs destroyed by spleen in 10-20 days)
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7
Q

Hereditary Spherocytosis:

What does it look like (3) and how is it diagnosed?

A

M: small, dark RBCs w/o central pallor zone, reticulocytosis, and cholelithiasis (pigment stones in 40-50% of pts)

D: history, hematology findings, and labs
- osmotic fragility test, inc. MCHC

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8
Q

Hereditary Spherocytosis:

How does it present clinically (4) and how is it treated?

A

C: variable anemia, splenomegaly, jaundice, gallstones

  • inc. risk of aplastic crisis due to Parovirus B19
  • stops hematopoiesis for a couple of weeks

T: splenectomy (corrects anemia but Howell-jolly bodies remain)
- inc. risk of sepsis (encapsulated bacteria)

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9
Q

G6PD Deficiency:

What are the two types, what are their genetics, and what is happening?

A

G6PD- (African Americans, less severe) and G6PD Mediterranean (more severe, shorter enzyme 1/2 life)

X-linked recessive

  • oxidants cause crosslinking of globin chains causes precipitates (Heinz bodies) which are removed by macrophages, creating “bite cells”

older RBCs more prone to hemolysis; younger RBCs not affected

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10
Q

What causes oxidative stress on G6PD? (FASN)

A

fava beans, antimalarial drugs (quines), sulfonamides, nitrofurantoins

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11
Q

Sickle Cell Anemia:

What mutation is it caused by and what four things are likely to decrease the rate of sickling?

A
  • hereditary hemoglobinopathy via glutamate –> valine mutation in beta-globulin (microvascular obstruction most serious feature)
  • Hb forms RBC polymers when deoxygenated, forming long needlelike fibers

Dec. sickling: inc. HbA, dec. MCHC/hydration, inc. pH, inc. microvascular transit

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12
Q

What are HbSC (Sickle Cell Disease) and Fetal Sickle Cell Anemia?

A

HbSC - compound heterozygotes (HbS and HbC genes) –> milder than sickle cell anemia

  • glutamic acid –> lysine (crystals on smear)
  • causes extravascular hemolysis

Fetal SC - have more HbF (protective), so problems often present at 6 months old
- hydroxyurea enhances HbF expression

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13
Q

What is the process of Sickle Cell Stasis?

A
  • inc. adhesion molecules (inflammation) cause cells to arrest while moving through microvasculature
  • inc. sickling and obstruction lead to hypoxia
  • free hemoglobin binds and inactivates NO = inc. vascular tone and inc. platelet aggregation
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14
Q

Sickle Cell Anemia:

What is Autosplenectomy, Vasoocclusive Crises, Sequestration Crisis, Aplasic Crisis, and what bone problems are seen?

A

AS: chronic erythrostasis causes splenic infact and fibrosis

VC: MOST IMPORTANT COMPLICATION

  • hypoxic injury/infarction episodes cause pain
  • manifests as dactylitis or acute chest syndrome
  • hard to differentiate from Acute Osteomyelitis

SC: massive entrapment of RBCs in kids spleen
- rapid enlargment, hypovolemia, shock

AC: Parovirus B19 infection dec. hematopoiesis

bones: marrow expansion = remodeling
- “Chipmunk” cheeks, prominent cheek bones
- skull changes resembling “crew cut”

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15
Q

Sickle Cell Anemia:

What is Dactylitis and Acute Chest Syndrome?

A
  • manifestations of Vasoocclusive Crisis

D: hand-foot syndrome

  • vasoocclusive infarcts = swollen hands/feet
  • seen in African America infants

ACS: vasooclusive crisis of lungs

  • most common cause of death in adult pts
  • often precipitated by pneumonia
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16
Q

What is the most common cause of death in children with Sickle Cell Anemia?

A

H. influenzae

  • causes septicemia and meningitis
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17
Q

What 4 pathogens are pts with Sickle Cell Anemia more at risk for?

A

S. pneumoniae, H. influenzae, neisseria (encaspsulated)

  • inc. risk of S. Typhi osteomyelitis
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18
Q

How is Sickle Cell Anemia diagnosed, what is its prognosis, and how can it be treated (2)?

A

D: clinical signs/symptoms, lab testing of hemoglobin

  • metabisulfite screen (+)
  • elecrophoresis

P: 90% survive to 20, 50% survive to 50+

T: hydroxyurea (inc. HbF) and HSC transplant

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19
Q

What is the difference between Beta0 and Beta+ in Beta Thalassemia?

What is the pathogenesis of Beta Thalassemia?

A

Beta0 - absent beta globin chain synthesis
- most common mutation is premature STOP codon

Beta+ - reduced but detectable bet globin synthesis
- most common mutation is splicing

P: unpaired alpha chain preceiptates, creating insoluble inclusions = membrane damage = APOPTOSIS of precursors

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20
Q

What are manifestations that occur in severe cases of Beta Thalassemia? (4)

A
  • massive erythroid hyperplasia; extramed. hematoe
    • “crew cut” and “chipmunk” facies
  • severe cachexia, iron overloading causing SECONDARY hemachromatosis
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21
Q

What cell changes are seen on peripheral smear of Beta Thalassemia? (4)

A

anisocytosis (variable size), poikilocytosis (variable shape), target cells (hemoglobin in center), and basophilic stippling

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22
Q

Beta Thalassemia Major:

Who is it most common in (3) and what Hb type is most prominent?

A
  • individuals have transfusion dependent anemia beginning at 6-9 months
  • Mediterranean, Africa, Southeast Asia
  • HbF hemoglobin is predominant
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23
Q

Beta Thalassemia Major:

What are 4 clinical impacts of disease and what are two major treatment options?

A
  • hepatosplenomegaly (hematopoiesis), massive erythroid hyperplasia, possible aplastic crisis

T: chronic transfusions (3rd decade survival)

- predisposed to 2nd hemachromatosis
- HSC transplant may occur
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24
Q

Beta Thalassemia Minor:

What is it, what does it cause (4), and what Hb type is most prominent?

What anemia must be ruled out if you believe your pt. has Beta Thalassemia Minor?

A
  • individuals with heterozygous alleles (MORE COMMON)
  • mild microcytic, hypochromic anemia, basophilic stippling, target cells, and erythroid hyperplasia
  • HbA2 hemoglobin is predominant

confirm diagnosis to rule out IRON DEFICIENCY ANEMIA

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25
Q

Alpha Thalassemia:

What is it, how does it differ from Beta Thalassemia clinically, and what are its 4 types?

A
  • inherited gene deletion causing absent or reduced alpha-globin chains
  • beta and gamma chains are more soluble, meaning less severe hemolysis and ineffective erythropoiesis
    types: Silent Carrier, a-thalassemia trait, Hemoglobin H disease, Hydrops Fetalis
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26
Q

Alpha Thalassemia:

What is the Silent Carrier Type?

A
  • deletion of single gene causing barely detectable reduction in synthesis
  • asymptomatic
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27
Q

Alpha Thalassemia:

What are the two alpha-thalassemia deletions and what disease is it clinically similar to?

A
  • Cis deletion: two genes deleted on 1 chromosome
    • common in Asians, offspring at inc. risk of disease
  • Trans deletion: one gene deleted from both chromo
    • common in African Americans
    • microcytosis w/minimal anemia

clinically similar to B-thalassemia Minor

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28
Q

Alpha Thalassemia:

What is the Hemoglobin H Disease and what disease is it clinically similar to?

A
  • 3 gene deletion common in Asians, creates HbH
  • Beta tetramers form w/inc. oxygen affinity, causing tissue hypoxia disproportionate to lvl of Hb
  • does NOT require transfusions

resembles B-thalassemia Intermedia

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29
Q

Alpha Thalassemia:

What is Hydrops Fetalis and what does it cause?

A
  • deletion of all 4 genes, creates Hemoglobin Barts (gamma globin tetramer w/greatly inc. oxygen affinity)
  • causes Fetal Distress Syndrome beginning 3rd trimester (requires lifelong transfusions)

HSC is curative

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30
Q

Paroxysmal Nocturnal Hemoglobinuria (PNH)

What is it, what 3 proteins is it deficient for, and how does it present clinically (4)?

A
  • acquired PIGA gene (GIP protein) mutation (subject to lyonization since its X-linked, so one mutation will fuck it up)
  • proteins: CD55 (DAF), CD59 (MIRL –> most important), and C8 binding protein

C: shallow nighttime breathing (respiratory acidosis inc. complement), mild anemia (chronic), hemosiduria –> iron deficiency

only hemolytic anemia caused by acquired genetic defect

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31
Q

Paroxysmal Nocturnal Hemoglobinuria (PNH):

What is the leading cause of death, how is it diagnosed, and what are 2 major treatment options?

A
  • Venous Thrombosis of hepatic, portal, or cerebral veins (5-10% develop AML)
  • Flow Cytometry to see GPI deficient RBCs

T: Eculizumab (prevents C5 conversion) or HSC transplant

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32
Q

What are Immunohemolytic Anemias and how are Direct and Indirect Coombs Tests used?

A
  • antibodies bind to RBCs causing their premature anemias

Direct Coomb’s Test - mix pt. RBCs mixed w/abs for human immunoglobins
(+) - if agglutenation occurs (Abs to Abs on RBCs)

Indirect Coomb’s Test - RBCs w/defined Ags are mixed with pt. serum
(+) - if pts. serum has Abs against Ags on RBCs

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33
Q

Warm Antibody Type of Immunohemolytic Anemia:

What is it, how does it work, and what does it lead to?

A
  • most COMMON type of immunohemolytic anemia caused by IgG abs
  • leads to extravascular hemolysis (phagocytes Fc receptor binding) and sequestering of spherocytes in spleen (splenomegaly)
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34
Q

How do Antigenic (2 examples) and Tolerance Breaking Drugs (1 example) cause immunohemolytic anemia?

A

A: agent binds to RBCs after IV infusion

  • hemolysis occurs after 1-2 wks
  • phagocytes eat –> extravascular hemolysis
  • penicillins and cephalosporins

TB: agent stims Abs against RBC antigens, usually Rh antigens
- alpha-methyldopa

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35
Q

Cold Agglutinin Type of Immunohemolytic Anemia:

What is it, what are its two types (A/C), and what does it lead to clinically (4)?

A
  • IgM Abs bind RBCs at low temperatures, usually in extremity vascular beds

Acute: self-limited, appearing after infection (EBV, CMB, flu, HIV)

Chronic: symptomatic (idiopathic or B cell neoplasms)
- more difficult to treat

  • leads to Raynaud’s, cyanosis, pallor; opsonized cells phagocytosed w/minimal complement hemolysis
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36
Q

Immunohemolytic Anemias:

Cold Hemolysin and RBC Trauma (What are they, what are they caused by, and what do they lead to?)

A

CH: IgG auto-Abs bind to P Ag on RBC in peripheral (cold) regions and cause paroxysmal cold hemoglobinuria when they return to central (warm) areas –> complement more effective here

RT: commonly caused by prosthetic cardiac valves and microangiopathic disorders (LUMINAL NARROWING)

  • fibrin/platelets inc shear stress –> injure RBCs
  • schistocytes –> helmet, triangle, burr cells
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37
Q

What is Microangiopathic Hemolytic Anemia most commonly seen with and what other blood disorders (2) is it also commonly seen in?

A

most associated with DIC (disseminated intravascular coagulation)

  • also seen in thrombotic thrombocytopenic purpura (TTP) and hemolytic-uremic syndrome (HUS)
38
Q

Megaloblastic Anemias:

What are they, what does the peripheral blood look like, and what does the bone marrow look like?

A
  • impairment of DNA synthesis leading to abnormally large RBC precursors due to ineffective hematopoiesis
    • usually B12 or folate deficiencies

P: large, oval RBCs (macro-ovalocytes)

  • appear hyperchromic and MCHC not changed
  • hypersegmented neutrophils

M: hypercellular with inc. blast forms

  • giant metamyelocytes/band forms
  • pancytopenia due to ineffective synthesis
39
Q

Pernicious Anemia

What is it and who does it commonly affect?

A
  • autoimmune gastritis impairs Intrinsic Factor required for B12 uptake in gut (autoreactive T cell response; auto-Abs do not cause pathology)
  • median age 60 and especially effects Scandinavians
40
Q

Vitamin B12 Deficiency:

How does the morphology of the GI and CNS change in patients with deficiency? What are 3 common consequences of having the disease?

A

GI: beefy red tongue, fundic gland atrophy, intestinalization (parietal cells –> goblet cells)

CNS: dorsal/lateral spinal tract demyelination = sensory ataxia, lower limb parasthesias

CC: inc. risk of gastric carcinoma, neuro disease (methylmalonic acid build-up), and atherosclerosis/thrombosis (inc. homocysteine)

41
Q

Vitamin B12 Deficiency:

How is it diagnosed (2) and how can it be treated?

A

D: inc. homocysteine and methylmalonic acid (meth. NOT inc. in Folic Acid deficiency), serum Abs to IF (pernicious anemia)

B12 challenge: hematocrit inc. in 5 days after B12 administration (CONFIRMED after seeing response)

T: high dose or parenteral B12/folate administration

42
Q

What are two ways that Folate Deficiency differs from Vitamin B12 Deficiency?

A
  • folate def. has NO neurological problems (CNS problems w/B12 deficiency)
  • methylmalonic acid within NORMAL limits (inc. methylmalonic acid w/B12 deficiency)
43
Q

What tapeworm is a potential cause of B12 deficiency and what is it found in?

A

Diphyllobothrium latum

  • found in fish
44
Q

Anemia of Folate Deficiency:

What are 3 causes of it, where can it normally be acquired, and what are 3 groups it is commonly associated with?

How is it treated?

A

C: dec. intake, inc. requirements, or impaired utilization
- similar pathologic features to B12 deficiencyI

Sources: green veggies/animal organ meat
- absorbed in proximal jejunum

seen in:

  • old, poor, alcoholics
  • people using phenytoin/oral contraceptives
  • methotrexate or other chemo drugs

Treat: folic acid administration

45
Q

What is the most common nutritional disorder in the world and how can it be diagnosed?

A

Iron Deficiency (most commonly due to CHRONIC blood loss in the Western world)

D: Prussian Blue Stain for hemosiderin granules (no stained iron in macrophages = diagnostically significant finding of iron deficiency)
- normally turns blue-black

46
Q

What is Ferritin and Hemosiderin?

A

F: storage form of iron found in liver, spleen, bones, muscles

H: partially degraded protein-shell granules of Ferritin
- most iron stored as hemosiderin in Iron Overload

47
Q

What is hepcidin and why is it important?

A
  • released from liver cells in response to inc. in intra-hepatic iron levels
  • regulates iron absorption in proximal duodenum by binding FERROPORTIN (blocks iron release from enterocyte to plasma and from macrophage storage pools)
  • hepcidin levels are directly related to total body iron stores (enterocytes slough off, allowing the body to excrete iron)
48
Q

Hepcidin and infection (what are two microbes that require iron to survive?)

A
  • hepcidin is structurally related to defensins (anti-bacterial), so iron sequestration enhances ability to fight off certain infections

EX: H. influenza and Yersinia enterocolitica (pseudo-appendicitis)

49
Q

What is iron deficiency in men or postmenopausal women diagnosed as until proven otherwise?

A

GI bleed! –> cancer or occult

think colon cancer

50
Q

Iron Deficiency Anemia:

What is its morphology (3) and what clinical findings does it cause (4)? What syndrome can it lead to?

A

M: microcytic, hypochromic anemia (started normocytic, normochromic) –> enlarged RBC central pallor
- Poikilocytosis (pencil cells)

C: koilonychia (spoon nails), hair loss, atropic changes (tongue and gastric mucosa), Pica

  • can lead to Plummer-Vinson Syndrome (late iron deficiency anemia causing atrophic glottitis and esophageal webbing)
51
Q

Iron Deficiency Anemia:

What are laboratory findings of disease? (4)

A
  1. HCT/Hgb decreased
  2. serum iron low
  3. plasma ferritin low (iron storage form)
    • inversely related to Total Iron Binding Capacity
  4. serum hepcidin is low
52
Q

Anemia of Chronic Disease:

Who is it most commonly seen in, what are 3 things that can cause it, and what is its pathogenesis?

A
  • most common cause of anemia in hospital pts. (microcytic, hypochromic anemia)

C: chronic infections, immune disorders, or neoplasms

P: systemic inflammation (IL-6 inc. hepcidin production)
- low serum iron, dec. TIBC, abundant iron stores

TREAT UNDERLYING CONDITION

53
Q

What is Apastic Anemia? What are its two models of pathogenesis?

A
  • syndrome of primary hematopoietic failure and attendant pancytopenia
  • autoimmune is most common cause and idiopathic causes are seen in 65% of cases

Extrinsic: immune-mediated progenitor suppression

  • Th1 causes IFNy and TNF (SUPPRESSORS)
  • antithymocyte globulin suppress T-cells

Intrinsic: stem cell abnormality

  • antigenically altered via drug/infectious agents
  • Hepatitis D/E?
54
Q

What is Fanconi Anemia and what two telomerase problems are seen in aplastic pts?

A

FA: auto recessive due to defective DNA repair protein complex (see w/congenital anomalies)
- kidney/spleen hypoplasia and thumb abnormality

Telomerase:

  1. Mutations (5-10% of adults)
    • premature HSC exhaustion and marrow aplasia
  2. Short Telomeres (50% of pts)
    • undiscovered defects or excessive SC replication
55
Q

Aplastic Anemia:

Wht does it look like, what does it cause clinically, and how is it treated?

A
  • hypocellular bone marrow (fat, fibrous stroma); do “dry-tap” on marrow since biopsy necessary for diagnosis
  • mucocutaneous bacterial infection, abnormal bleeding, systemic hemosiderosis (mutiple transfusions) –> PANCYTOPENIA

T: bone marrow transplant (5 year survival in 75%+) or immunosuppresion in older pts

56
Q

What is Pure Red Cell Aplasia?

A
  • primary marrow disorder that ONLY suppresses RBC progenitors (THYMOMA and Parovirus B19 associated)

PB19 –> infects RBC precursors and can lead to aplastic crisis in pts w/hemolytic anemias (HIV inc. infection)

T: with thymoma resection (50% have improvement) or immunosuppression if NO thymoma

57
Q

What is Myelophthisic Anemia?

What is it most commonly caused by?

A
  • space occupying lesions replace normal marrow elements
  • causes Leukoerythroblastosis (abnormal blast/immature cell release), “Teardrop RBCs” from having to escape fibrotic marrow

caused by: metastatic breast/lung/prostate cancer

58
Q

Chronic Renal Failure leading to anemia and treatment

A
  • anemia is proportional to uremia severity (kidneys produce less EPO causing inadequate RBC production)

T: recombinant EPO +/- Iron therapy

hepatocellular liver disease can also cause anemia due to toxins/infections/cirrhosis

59
Q

Polycythemia:

What is the difference between Relative and Absolute (P/S) versions?

A
  • abnormally high RBC count (usually w/inc. Hb lvls)

Relative: inc. hemoconc. due to dec. plasma vol.

  • usually from dehydration
  • Gaisbock Syndrome: stress version (HTN/anxious)

Absolute: inc. in total red cell mass

  • Primary: instrinsic abnormality in RBC precursors
  • Secondary: RBC precursors respond to inc. EPO

Renal Cell carcinomas are known to secrete erythropoietin

60
Q

What is Polycythemia Vera?

A
  • most common cause of primary polycythemia
  • myeloproliferative disorder associated w/mutations leading to EPO-independent RBC progenitor growth

HIF-1a - hypoxia-inducing factor; stimulates EPO gene transcription

61
Q

What is the difference between Prothrombin and Partial Thromboplastin Time?

A

PT: assesses EXTRINSIC coagulation pathway

  • plasma clot after thromboplastin/Ca addition
  • prolonged due to Factor VII deficiency
  • measured in pts taking WARFARIN (coumadin)

PTT: assesses INTRINSIC coagulation pathway

  • plasma clot - kaolin, cephalin, Ca addition
  • prolonged due to Factor VIII, IX, XI, XII defic.
  • measured in pts taking heparin

do PTT testing if you thing HEMOPHILIA

62
Q

Vessel Wall Abnormalities:

What do they lead to, what infections (3) are potential causes of them, and what does lab testing reveal about them?

A
  • relatively common, causing petechiae and purpura w/o serious bleeding
  • infections of meningococcemia (can be catastrophic), rickettsioses, and Neisseria can lead to it

Labs: platelet count normal, PT/PTT are normal

63
Q

What is Henoch-Schonlein Purpura? What are 4 classic symptoms of it?

A
  • systemic hypersensitivity due to immune complex deposition (IgA), usually in the glomerular mesangial region
  • causes purpuric rash, colicky abdominal pain, polyarthralgia, and acute glomerulonephritis

deposition of immune complexes within vascular walls

64
Q

Hereditary Hemorrhagic Telangiectasia (WOR Syndrome):

What is it and what is it caused by, how does it present, and how is it treated?

A
  • dilated, tortuous, thin-walled vessels due to TGF-B signaling dysregulation (AutoDominant inheritance of CD105 gene endoglin)
  • causes bleeding under mucous membranes of NOSE (recurrent EPISTAXIS most common symptom), tongue, mouth, eyes, GI tract (Vermillion border of lip and on tongue)

T: mostly benign, surgery/photoablation in select pts

65
Q

What is Thrombocytopenia and what are its 4 major categories?

A
  • platelet count BELOW 100,000 (counts of 20,000-50,000 can exacerbate posttraumatic hemorrhage)

Categories:

  1. Dec. Production - marrow output suppressed
  2. Dec. Survival - inc. consumption/activation
    • mechanical injury, DIC/thrombotic microangiopathy
  3. Sequestration
  4. Dilution - see in prolonged storage for transfusion
66
Q

Chronic Immune Thrombocytopenic Purpura (ITP):

What is it, who does it commonly affect, and what lab values does it produce (3)?

A
  • primary/secondary auto-Abs (IgG) destroying platelets (secondary associated with SLE, HIV, CLL)
  • no splenomegaly noted even though platelets are removed there
  • seen in women < 40 yo, and is 3x more likely in F’s

Labs: normal PT/PTT, low platelet counts with large ones seen on smear, inc. megakaryocytes

67
Q

Chronic Immune Thrombocytopenic Purpura (ITP):

How is it diagnosed, how does it present clinically, and how can it be treated (3)?

A

D: diagnosis of exclusion due to no reliable Ab tests

C: bleeding into skin/mucousal surfaces

  • epistaxis, easy bruising, gum bleeding
  • no splenomegaly or lymphadenopathy (B cell neos)

T: splenectomy (normalizes platelet count, IVIG or Rituximab, TPO mimetics to stimulate production

68
Q

Acute Immune Thrombocytopenic Purpura (ITP):

What is it and who does it commonly affect? How is it treated?

A
  • childhood disease appearing 1-2 wks after self-limited viral infection
  • auto-Abs to platelets develop but are self-limited with resolution in 6 months
  • 20% of pts can persist to a chronic form resembling CHRONIC ITP
69
Q

What are 3 common drugs that cause Drug-induced Thrombocytopenia and how do they cause the disease?

A

quinine, quinidine (malarial drugs), and vancomycin

  • bind platelet glycoproteins and create antigenic determinants that are recognized by Abs
  • Abs bind to them, allowing for macrophage ingestion and platelet removal
70
Q

What is Type II Heparin-induced Thrombocytopenia (HIT)?

A
  • Abs form to Heparin-Platelet Factor 4 complexes (occurs 5-14 days after therapy begins)
  • causes DVT that can become pulmonary embolisms (setting of thrombocytopenia) and can clot large arteries leading to limb loss

DISCONTINUE THERAPY and find another anti-clotting drug

71
Q

What is one of the most common hematological manifestations of HIV infection and how does it infect?

A

THROMBOCYTOPENIA

  • through CD4 receptors and CXCR4 coreceptors on megakaryocytes
72
Q

What are two common examples of Thrombotic Microangiopathies?

How can they be separated from DIC?

A
  1. Thrombotic Thrombocytopenic Purpura
  2. Hemolytic Uremic Syndromes
  • both examples have NORMAL PT/PTT times because mode of action is DIRECT platelet activation
  • DIC would follow coagulation cascade and has abnormal PT/PTT times
73
Q

Thrombotic Thrombocytopenic Purpura (TTP):

What is it, who does it commonly affect, and what is its classic pentad of symptoms?

What do labs show and how can it be treated?

A
  • hyaline thrombi occlude capillaries of organs (dec. ADAMSTs13 - normally degrades vWF either by auto-Abs or hereditary mutation)
  • commonly affects females

Pentad: fever, mental changes, renal failure, thrombocytopenia, and microangiopathic hemolytic anemia

Labs: PT/PTT normal in early disease, late suggest DIC
Treatment: plasma exchange/plasmapheresis
- untreated = 100% MORTALITY

74
Q

Hemolytic Uremic Syndrome:

Why is the difference between its Typical and Atypical form?

How can it be differentiated from TTP?

A

Typical: drug/infection endothelial damage

  • children/elderly w/E. coli dysentery (uncooked beef)
  • Shiga-like toxin leads to bloody diarrhea
  • irreversible renal damage, supportive treatment

Atypical: acquired/inherited Factor H (CD46) or I defect

  • normally prevent excess Alt. Complement pathway activation
  • immunosuppresion for pts. with auto-Abs

different from TTP due to LACK of NEUROLOGICAL changes

75
Q

Bernard-Soulier Syndrome:

What is it and what will it not aggregate to?

A
  • defective platelet adhesion to subendothelial matrix due to deficiency of complex Ib-IX (receptor for vWF)
  • severe bleeding tendencies and giant platelets on smear

no aggregation - ADP, collagen, epinephrine, thrombin
- ABSENT aggregation to RISTOCETIN

76
Q

Glanzmann Thrombasthenia:

What is it and what will it not aggregate to?

A
  • defective platelet aggregation due to auto recessive dysfunction of IIb/IIIa (binds fibrinogen for platelet agg)
  • severe bleeding tendencies, normal platelets

no aggregation - ADP, collagen, epinephrine, thrombin
- WILL aggregate to RISTOCETIN

77
Q

How does Aspirin and other NSAIDS affect platelets?

A
  • aspirin is a potent, irreversible inhibitor of COX, which is required for synthesis of TxA2 and PGs (platelet activators)
  • acquired defect in platelet aggregation
78
Q

What disease is hemarthrosis after minor stress a sign of?

A

Hemophilia A or B, but not vWF related

i.e. coagulation factor deficiencies

79
Q

Vitamin K Deficiency:

What is it, what causes it (3), and what does it lead to clinically?

How is it treated?

A
  • vitamin K activated by epoxide reductase (liver); leads to impaired synthesis of Factors II, VII, IX, X, Protein C (“1972 and C)
  • Warfarin impairs vitamin K; also due to chronic antibiotics (mess up GI bacteria), severe liver disease

C: prolonged PT –> bleeding and hemorrhage

T: replacement of deficiency (12-18 hr correction)

80
Q

How do Clotting Factor abnormalities clinically manifest? (3)

A
  • large ecchamoses/hematomas after injury, or prolonged bleeding after laceration/surgery
  • can bleed into GI/GU tracts or weight-bearing joints (Hemarthrosis)
81
Q

Von Willebrand Disease:

What is it and how does it look on labs?

A
  • most common inherited bleeding disorder of humans; usually unnoticed till surgery or dental procedure
  • autosomal DOMINANT disorder

Labs: factor VIII is reduced (plasma protein lvl low), prolonged PTT time (Hemophilia A and B also have prolonged PTT, so need to differentiate)

82
Q

Von Willebrand Disease:

What is the difference between Type 1, Type 3, and Type 2?

A

T1: AD quantitative defect; most common subtype (70%) w/mild-moderate deficiency

  • PTT may be prolonged
  • point mutation

T3: AR quantitative defect; very low levels with SEVERE CLINICAL manifestations

  • Factor VIII stability affected, PTT may be prolonged
  • frameshift/deletion of BOTH alleles
  • hemarthrosis may be seen

T2: AD qualitative with normal protein expression

  • missense mutation = defective multimer assembly
  • 25% of cases have mild-moderate bleeding
83
Q

Hemophilia A:

What is it, how does it present clinically, and how can it be treated?

A
  • Factor VIII deficiency (most common hereditary disease associated with life-threatening bleeding)
  • x-linked recessive trait; X chromosome inversion is most severe form, leading to NO synthesis of F VIII

C: no petechiae, tendency to bleed at particular sites (joints, muscles, CNS); prolonged PTT, normal PT

T: recombinant factor VIII infusions (replace what is missing) and prophylaxis before surgery

84
Q

Hemophilia B (Christmas Disease):

What is it, how is it diagnosed, and what is its treatment?

A

Factor IX deficiency that is X-linked recessive (clinically identical to Hemophilia A)

D: assay of factor levels, prolonged PTT, normal PT

T: recombinant Factor IX (replace what is missing)

85
Q

Disseminated Intravascular Coagulation:

What is it, what are 3 common signs of it, and how is it caused?

A
  • acute, subacute, or chronic thrombo-hemorrhagic disease due to excessive activation of coagulation and thrombi formation in microvasculature
    signs: tissue hypoxia, infaction, hemorrhage

triggered by the release of tissue factor or procoagulants, or widespread injury to the endothelial cells

caused by: sepsis, major trauma, certain cancers (33% of pts), or obstetric complications (50% of pts)

86
Q

Disseminated Intravascular Coagulation:

What is the difference between Acute and Chronic presentation, what are common clinical complications, and what is the treatment?

A

Acute: obstetric complications/trauma: bleeding diasthes
Chronic: carinomatosis w/thrombotic complications

C: microangiopathic hemolytic anemia, respiratory (cyanosis, dyspnea, failure), neuro signs

T: remove or treat underlying cause quickly since DIC is well-established as a DEATH SENTENCE

87
Q

Transfusion Complications:

Febrile non-hemolytic and Allergic Reactions

A

FNH: fever/chills +/- dyspnea (6 hrs after transfusion)
- inflammation from donor leukocytes

Allergic: most common in pts. w/IgA deficiency

  • life-threatening in pts. who have been sensitized
  • mild, most pts. respond to antihistamines
  • IgG recognizes IgA in blood
88
Q

Transfusion Complications:

Acute vs Delayed Hemolytic Reactions

A

Acute: due to preformed IgM Abs against donor RBCs

  • ABO compatibility (fix complement)
  • rapid onset (fever/chills/shaking)
  • (+) direct Coomb’s test

Delayed: due to IgG Abs against RBC Ags (sensitized)

  • Abs to Rh, Kell, Kidd activate compliment
  • Abs can also opsonize = spherocytosis
  • (+) direct Coomb’s, dec. haptoglobin, inc. LDH
89
Q

Transfusion Complications due to Infection

A
  • bacterial infections due to skin contamination at time of donation
  • more likely with platelet transfusion since they must be stored at ROOM temperature
  • frequent donors or IV drug users who get past screening = LAB ERROR
90
Q

Transfusion-related Acute Lung Injury (TRALI)

A
  • activated neutrophils in lung microvasculature (more frequent in pts with lung disease)
  • transfused Abs attack neutrophils, leading to rapid/diffuse respiratory failure and diffuse bilateral pulmonary infiltrates
  • treatment is support since it is unresponsive to diuretics
91
Q

TRALI “2 Hit” hypothesis

A

First hit: priming event that leads to sequestration and sensitization of neutrophils in microvasculature of the lung

Second hit: primed neutrophils are activated by factor present in transfused blood product

most common Abs are those that bind MHC proteins, especially MHC1

SBL (Skin, Blood, Lymph) Exam 1 and 2 (22 decks)

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