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Hematology > Thalassemia > Flashcards

Thalassemia Flashcards

1
Q

1 Hemoglobin consists of

A

4 Fe2+
4 Porphyrin
4 globin chains

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2
Q

globin chain production

A

Required 4 chains of AA
- 2 homologous chains

Alpha = chromosome 16
- alpha (Hgb A1,A2, F, Gower2)
- (hgb Gower 1, portland)

Beta = chromosome 11
- beta (hgb A1)
- delta = hgb A2
- gamma (hgb F, porland
- epsilon (hgb Gower 1 and 2)
-

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3
Q

Hemoglobin F

A

a2y2

60-90% in fetus

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4
Q

Hemoglobin A1

A

a2b2
95-97%
Adult

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5
Q

Hemoglobin A2

A

a2d2

2-3%

Adult

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6
Q

hemoglobin electrophoresis

A

problem: some hgb chains will migrate to the same site.

Combat this by running different types of agar held at different pHs

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7
Q

Cellulose acetate

A

pH: 8.6

Loaded at cathode

Alkaline pH gives hemoglobin a negative charge which travels from (-) cathode to (+) anode

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8
Q

Citrate agar

A

pH: 6.0

Load in center

Hgb chains will travel in either direction depending on its type

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9
Q

Isoelectric focusing

A
  • uses a pH gradient across polychrylamide gel
    1. seperated based on isoelectric point
    2. expensive and slow
    3. creates distinguishable bands
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10
Q

high performance liquid chromatogrpahy

A

pushes sample in solvent (mobile phase) at high pressure through a column of stationary phase material that allows us to seperate and identify compounds

  • expansive and small sample size
  • fully automated and quantitaitve
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11
Q

Kleihauer Betke-Stain / KB stain

A

fetal hgb can be quantified by an acid-elution stain.

acidic pH (3.3) is applied to an air-dried, alcohol fixed blood smear
- hgb A is eluted off
- hgb F is resistant

smear is further treated and stained with eosin or erythrosine
- normal adult red cells - ghost cells (mom)
- hgb F cells - stained baby

Fetal hgb cells can be quantitated to determine fetal trauma in pregant mom or hereditary persistance of hgb f

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12
Q

gower 1
gower 2
portland

A

embryo (z2e2)
embryo (a2e2)
embryo (z2 y2)

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13
Q

hemolytic anemia

A

resulting from the shortened survival of RBCs

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14
Q

RBC destruction lab findings

A

Decreased
- RBC count, hgb, hct
- haptoglobin
- hemopexin

increased
- total bilirubin
- methemal bumin
- hemoglobinemia
- hemoglobinuria
- LDH

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15
Q

RBC count

A

Bone marrow erythroid hyperplasia
(m:e shifting towards E)

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16
Q

osmotic fragility

A

determines RBC hemolysis resitance by placing blood in different concentrations of hypotonic saline

in hypotonic saline… RBC will take in water and swell, until
- reach equilibrium
- cell leaks/ruptures (lyses)

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17
Q

Thalassemia

A
  • Hemolytic anemia
  • hemoglobinopathy
  • microcytic, hypochromic anemia
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18
Q

thalassemia definition

A

group of disorders that result in decreased production of globin chains in hgb resulting in microcytic, hypochromic anemia

defect in alpha or beta chain

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19
Q

thalassa is greek for

A

“sea” or “sea in the blood”

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20
Q

1st discovered by Thomas cooley and Pearl Lee

A
  • first named “cooleys anemia” found in a population of mediterrabeab children

now termed Beta Thalassemia Major

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21
Q

haplotype

A

group of genes inherited together from a single parent

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22
Q

Chain 0

A

gene results in complete absence of globin chain.

ex: a0 or b0

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23
Q

Chain +

A

gene results in reduced production of globin chain

a+ or B+

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24
Q

type of thalassemia is going to named after the chain most affected

A

alpha thalassemia involved missing/mutated alpha genes

same with beta ^

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25
Q

Thalassemia pathophysiology

A
  1. abnormal gene causes failure to produce functional mRNA for specific globin chain
  2. any specific globin chain produced are structurally normal, but decreased (or absent)
  3. decerase amount of normal hgb(A1)
  4. rate of synthesis between a/b are not equal
  5. imbalance of 2 types of homologous chains
26
Q

Alpha (a) thalassemia

A

excess beta and gamma globin chains build up

  • Hemoglobin Bart’s = 4 gamma chains
  • Hemolgobin H = 4 beta chains

tetramers are useless and precipitate in older cells

shorten life span by hemolysis

27
Q

hemoglobin bart’s

A

4 gamma chains

28
Q

hemoglobin H

A

4 beta chains

29
Q

Beta B thalassemia

A

excess alpha build up

forms pairs of a2

pairs precipitate in RBC precursors

causes apoptosies in RBC precursors in BM

results in ineffective erythropoiesis

30
Q

Beta thalassemia info

A
  • high frequency in mediterranean area
  • doesn’t present until switch is complete from gamma chain syntehsis -> beta chain syntehsis
    1. usually after birth
    2. clinically seen during 1st year of life

body compensates by increase gamma and delta chains to form hgb F and hgb 2

31
Q

B thalassemia - B+

A

gene produces a reduced amount of beta chains

32
Q

Type 1 B+

A

10% of normal beta production
- least amount of globin chains of the three types

33
Q

Type 2 B+

A

50% of normal beta production

34
Q

type 3 B+

A

have a greater amount of beta production and very mild symptoms

35
Q

Normal conditions (B thalassemia)

A

Genetic haplotype: BB

No anemia

36
Q

B Thalassemia Minor

A

haplotype: BB0, BB+

Also called Beta thalassemia trait

37
Q

B thalassemia intermedia

A

B+B+

Less severe B+ types

38
Q

B thalassemia Major

A

B0 B0
B+ B+
B0 B+

Most severe

39
Q

B Thalassemia Minor

A

BB0 or BB+

  • mild increase in Hgb F and Hgb A2
  • mild microcytic, hypochromic anemia; although RBC count may be normal/increased

Usually asymptomatic, but may see symtpoms if under stress (ex: pregnancy)

40
Q

B thalassemia intermedia

A

B+ B+, with less severe types

  • not transfusion dependen t
  • bridge between minor and major in terms of severity
  • varible anemia symptoms
    1. jaundice
    2. splenomegaly
    3. long surviving thalassemia symptoms
  • treatment: supportive therapy with occasional transfusion
41
Q

B thalassemia major

A

B0 B0, B+B+, B+B0
(homo and heterozygous compounds)

Usually begins presentation during first year of life
- gamma chain - beta switching

symptoms: failure to thrive, pallor, anemia, enlarged spleen jaundice and irritability

42
Q

B thalassemia major pathophysiology

A

Bone changes (skull, long bones, hand)

Liver and spleen enlarge - hepatosplenomegaly

43
Q

B thalassemia major - bone changes

A

Hand Bone

Mongoloid faces
- overgrown “moon face” with prominent cheekbones, wide-spaced eyes, sunken nose, flot bones, face rounded.

Skull
- radiating striations giving typical “hair on end” appearance

44
Q

B thalassemia major - untreated

A

Children will have numerous complications
- *massive hepatosplenomegaly - due to extramedullary erytropiesis *
- recurren tinfection
- spontanous fractures
- leg ulcers
- dental problems

Usually dies in early childhood or short after birth

45
Q

B thalassemia major - treatment

A

Lifelong recurrent blood transfusion

splenectomy (after 5 yrs old)

Future options: BM/ stem cell transplant

46
Q

B thalassemia major - treatment options

A

Mutliple transfusions + increased iron absorption (ineffective erythropoiesis) = iron overload

Transfusion treatment plans should include iron chelation therapy

47
Q

B thalassemia major Lab findings

CBC
Hemoglobin electrophoresis

A

CBC
- low hgb (2-3 g/dl)
- low MCV, MCH, MCHC
- Increased RDW

Electrophoresis
- mostly Hgb F and Hgb A2

48
Q

B thalassemia major - peripheral smear

A

Microcytic (4+), hypochromic (4+)

Anisocytosis and Poikilocytosis

Target cells

Schistocytes / fragments

Basophilic Stippling

Accelerated (ineffecive) erythropoiesis
- polychromasia
- lots of nRBCs
- Howell jolly bodies

49
Q

Alpha thalassemia info

A
  • asian populations
  • manifest in utero or immediately at birth
  • during fetal life
    1. gamma chain build up

-After birth
1. beta chain buildup

Tetramers of excess chains form:
- Hgb Barts = 4gamma chains
- Hgb H = 4 beta chains

50
Q

Alpha thalassemia haplotypes

A

2 alpha (a) genes (a1a2) are present on chromosome 16

51
Q

a0 thalassemia = a thalassemia 1(–)

A

complete absence of any alpha chains

borth alpha genes on chromosome 16 are nonfunctioning

52
Q

a+ thalassemia = alpha thalassemia 2 (-a)

A
  • reduction in output of alpha chains
  • one gene is functonal and other is nonfunctional
53
Q

normal conditions

A

aa

(aa/aa)

54
Q

silent carrier of alpha thalassemia

A

aa+

(aa/a-)

55
Q

alpha thalassemia minor

A

aa0 (aa/–)
a+a+ (-a/-a)

56
Q

Hemolgobin H disease

A

a0a+

(–/-a)

57
Q

Hemoglobin Bart’s hydrops fetalis syndrome

A

a0a0

(–/–)

58
Q

silent carrier of alpha thalassemia

A

aa+ (aa/a-)

small amount of hgb bart’s at birth, but disappears during development
- eventually leads to normal hgb electrophoresis

asymptomatic

most of you will see borderline low MCV (78-80 fL)

59
Q

A thalassemia minor

A

aa0 (aa/–) or a+a+ (-a/-a)

  • hgb Bart present at birth 5-15% but disappears during development and foes not go on to produce hgb H
    1. eventually had normal hgb electrophoresis

Mild microcytic, hypochromic anemia

60
Q

Hemoglobin H disease

A

a0 a+ (–/-a)
- variable degree of microcytic, hypochromic anemia and splenomegaly or bone related changes.

5-40% Hgb H (4 beta chains)
remaining is Hgb A1 and A2
Small amounts of Hgb Barts (4 gamma chains)

RBC gives “golf ball apperance” with supervital stain

61
Q

Hemoglobin Bart’s Hydrops Fetalis Syndrome

A

a0a0 (–/–)

lethal disease - usually stillbirth or spontaneous abortion.

no alpha chains produces
only Hgb present after embryonic phase is :
Hgb Barts - 4 gamma chains

Length of gestation is dependent on Hgb Portland and Hgb Gower I production since Hgb Bart cannot deliver oxygen

62
Q

Thalassemia general lab findings

A

CBC
- Low Hgb
- Low MCV
- Low MCH
- Low MCHC

Iron Studies
- N/ High serum iron
- high serum ferritin
- normal TIBC
- normal to high tranaferrin Sat%

Peripheral Smear:
- microcytic, hypochromia
- Reticulocytosis
- Poikilocytosis - elliptocytes, target cells, fragments.

Osmotic fragility
- decreased. due to higher surface to volume ratio

Hematology (36 decks)

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