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Hematology 1 > (M) Week 9: Special test for assessing certain hemoglobin disorders > Flashcards

(M) Week 9: Special test for assessing certain hemoglobin disorders Flashcards

1
Q

screening test to evaluate the presence of Hgb S in the patient’s blood

A

Dithionite solubility test

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2
Q

an unstable hemoglobin where point mutation of a single amino acid occurs in the beta globin chain

A

Hgb S

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3
Q

Hgb S is a genetic defect that causes the substitution of glutamic acid with _________ on the ___ position of amino acid in either one or two beta globin chains of the hemoglobin

A

valine on the 6th position

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4
Q

Hgb S causes the hemoglobin to ___________ within the red cells that changes the appearance of RBCs from disc to __________

A

precipitate
sickle shaped

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5
Q

Shape change to sickle may be triggered by the following factors:

A

hypoxia
acidosis
dehydration

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6
Q

What are the three forms of hemoglobin defect

A

sickle cell anemia = Hgb SS
sickle cell trait = Hgb AS
sickle cell disease = Hgb SC, SG, SD, SE, S-Beta thalassemia

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7
Q

which test principle is this:

The red cells are placed in a solution containing saponin and sodium dithionite reagent.

A

dithionite solutbility test

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8
Q

What is the action of the saponin reagent in the dithionite solubility test?

A

lyses the red cell, liberating the hemoglobin

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9
Q

What is the action of the sodium dithionite reagent if Hgb S is presnet

A

Hgb S is oxidized and forms tactoids / precipitates

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10
Q

Which diseases cause a positive result in the dithionite solubility test

A

Hgb SS / Hgb AS

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10
Q

What is the positive test result for dithionite solubility test

A

precipitates that causes turbidity

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11
Q

Which diseases causes a negative result on the dithionite solubility test?

A

sickle cell diseases

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12
Q

Used as a screening test for Hgb S

A

sickling test / sodium metabisulfite

+ dithionite solubility test

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13
Q

What shape does RBCs turb into when there is a presence of Hgb SS or As after being incubated with sodium metabisulfite

A

holly leaf appearance

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14
Q

a technique used to identify the specific type of hemoglobin present on an individual’s blood

A

Hgb electrophoresis

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15
Q

What blood disorders do Hgb electrophoresis confirm?

A

thalassemia and other hemmoglobinopathy

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16
Q

What are the two types of Hgb electrophoresis

A

cellulose acetate Hgb electrphoresis
citrate Hgb electrophoresis

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17
Q

what is the pH environment of cellulose acetate Hgb electrophoresis

A

8.0

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18
Q

what is the pH environment of citrate Hgb electrophoresis

A

6.0-6.2

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19
Q

What are the Hgb standards used for Hgb electrophoresis

A

Hgb A1
Hgb F
Hgb S
Hgb C

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20
Q

what is the order of migration in cellulose acetate Hgb electrophoresis (fastest to slowest)

A

Hgb A1
Hgb F
Hgb S
Hgb C

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21
Q

to which direction do the Hgb standards in cellulose acetate Hgb electrophoresis migrate to?

A

toward the anode (positive charge)

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22
Q

what is the order of migration in citrate Hgb electrophoresis (fastest to slowest)

A

Hgb C
Hgb S
Hgb F
Hgb A1

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23
Q

to which direction do the Hgb standards in citrate Hgb electrophoresis migrate to?

A

Hgb C and S = anode area (positive)
Hgb F and A1 = cathode area (negative)

24
Q

Where do Hgb D and G migrate when using the cellulose acetate Hgb electrophoresis

A

same point as Hgb S

25
Q

Where do Hgb E, O-Arab, and Hgb A2 migrate using the cellulose acetate medium

A

same point as Hgb C

26
Q

Where do the Bart’s Hgb, Hgb I, and Hgb H migrate to using the cellulose acetate medium?

A

goes to the same area where Hgb A1 but faster

27
Q

where do the Hgb A2, D, G, E, and O-Arab migrate to in the citrate medium?

A

same point as Hgb A1 (cathode)

28
Q

Test to determine the degree of distribution of the red cell containing Hgb F in a given specimen

A

Acid elution test

29
Q

which disorders are characterized to have a high Hgb F level

A

Hereditary persistence of fetal hemoglobin (HPFH)
fetal red cells in maternal circulation

30
Q

which test principle is this:

blood smears are fixed with ethyl alcohol and then incubated in a citric acid solutioni

A

Acid elution test

31
Q

Blood sample for acid elution test can be from either one of the following:

A

finger stick or EDTA sample (less than 6 hrs old)

32
Q

RBC with Hgb F (will/will not) be lysed when subjected to an acid solution

A

will not be

33
Q

What are the stains used for the blood smears in acid elution test?

A

hematoxylin stain
erythrosin B

34
Q

Acid elution test

hematoxylin is used to stain what?

A

WBC nuclei

35
Q

Acid elution test

erythrosin B is used to stain what?

36
Q

how many fields should the medical technologist view in the stained slides for acid elution test?

37
Q

what is the formula for the number of Hgb F / field

A

Hgb F RBC / field - # intact RBC counted / # of field counted

then multipled to 100

38
Q

What is the formula for the % of Hgb F

A

% of RBC with Hgb F = # Hgb F RBC /field divided by the ave # of RBC / field x 100

39
Q

In Hereditary persistent fetal hemoglobin, the amount of Hgb F is even in all red cells which
makes it stained (consistently/ inconsistently)

A

consistently

40
Q

disorders where Hgb f is variable

A

thalassemia
acquired aplastic anemia
sickle cell
other hemoglobinopathies

41
Q

This may resist elution by the acid and may cause confusions and discrepancy in the laboratory report for acid elution test

A

reticulocytes

42
Q

test used to quantify the concentration of Hgb F in a given specimen

A

alkali denaturation test

43
Q

normal levels of Hgb F in newborns

44
Q

normal Hgb F level for 4 month old babies

45
Q

what should be the Hgb concentration for 6-12 month olds

45
Q

what is the Hgb F level in hereditary persistent fetal hemoglobin

46
Q

what is the Hgb f level in sickle cell anemia

A

normal to 20%

47
Q

what is the Hgb F levels in beta thalassemia minor

48
Q

what is the Hgb F levels in beta thalassemia major

49
Q

high or low Hgb F levels are observed in the following:

acquired aplastic anemia
megaloblastic anemia
PNH
myelofibrosis
leukemia
refractory anemia
pregnancy

50
Q

what are the two methods of alkali denaturation test

A

Betke method
Singer method

51
Q

what reagent is used in the Betke method of alkali denaturation test

A

sodium hydroxide

52
Q

what reagent is used in the singer method of alkali denaturation test

A

potassium hydroxide

53
Q

Which test is this the principle of:

red cell hemolysate is incubated with an alkali solution which allows the denaturation of all forms of hemoglobin except Hgb F

A

alkali denaturation test

54
Q

the denatured hemoglobin will be precipitated with what reagent?

A

ammonium sulfate

55
Q

T or F

Hgb F is precipitated in the solution after the addition of ammonium sulfate

A

F (it is left in the solution)

whats eluted is other forms of HGB

56
Q

What is used after the alkali denaturation test to determine the optical density of the filtrate

A

cyanmethemoglobin test

57
Q

what is the formula to calculate the precent concentration of Hgb F

A

%Hgb F = (OD of Hgb F / OD of total Hgb x 10) 100

Hematology 1 (32 decks)

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