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Hematology Lab > HgB & Hct > Flashcards

HgB & Hct Flashcards

1
Q

Also known as Respiratory Pigment

A

Hemoglobin

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2
Q

One of the tests used to diagnose and follow the treatments of anemia.

A

Hemoglobin

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3
Q

What is the main component of hemoglobin?

A

Red blood cells (95%)

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4
Q

In what state does iron bind to oxygen?

A

Ferrous state or Fe2+

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5
Q

The portion that determines the type of
hemoglobin

A

Globin

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6
Q

How many subunits does each Hgb have?

A

4 heme & 4 globin

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7
Q

1 heme is capable of carrying how many moles of O2?

A

1 mole

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8
Q

2 alpha chains/2 beta chains

A

Hemoglobin A

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9
Q

2 alpha chains/2 delta chains

A

Hemoglobin A2

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10
Q

2 alpha chains and 2 gamma chains

A

Hemoglobin F (1-2%)

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11
Q

This is coded by Chromosome 16

A

Alpha chain

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12
Q

Gamma, delta, and beta chains are coded by?

A

Chromosome 11

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13
Q

Types of Abnormal Hemoglobin

A

Hemoglobin S
Hemoglobin C
Hemoglobin E
Hemoglobin D
Hemoglobin G
Hemoglobin Lepore

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14
Q

Hemoglobin whose structures have been modified due to drugs or environmental chemicals

A

Hemoglobin variants/ Abnormal Hemoglobin Pigmentation/ Dyshemoglobin

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15
Q

Can cause increased O2 affinity thus decreasing the efficiency of Oxygen to be delivered to the tissues

A

Methemoglobin

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16
Q

Methemoglobin is caused by?

A

oxidants (Nitrite, Primaquine,
dapsone, Benzocaine) or Methemoglobin Reductase deficiency

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17
Q

Methemoglobin can be treated by

A

administration of Ascorbic Acid and Methylene Blue

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18
Q

Sulfhemoglobin is caused by?

A

sulfonamides, phenacetin, nitrites,
phenylhydrazine

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19
Q

Addition of Hydrogen sulfide to the hemoglobin (greenish pigment) causes

A

Sulfhemoglobin

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20
Q

The only irreversible Abnormal hemoglobin pigmentation

A

Sulfhemoglobin

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21
Q

Caused by the combination of heme and carbon monoxide

A

Carboxyhemoglobin

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22
Q

CO has an affinity to hemoglobin of ____ than that of oxygen

A

240x

23
Q

Carboxyhemoglobin can be treated by

A

Oxygen Saturation or
Hyperbaric oxygen therapy

24
Q

This is the reference method approved by the Clinical and Laboratory Standards Institute for Hemoglobin determination.

A

The cyanmethemoglobin (hemoglobincyanide) method

25
Q

Principle of cyanmethemoglobin (hemoglobincyanide) method

A

In the cyanmethemoglobin method, blood is diluted in an alkaline Drabkin solution of potassium ferricyanide, potassium cyanide, sodium bicarbonate, and a surfactant.

26
Q

The absorbance of the cyanmethemoglobin is at _____

A

540 nm

27
Q

The absorbance of the cyanmethemoglobin at 540 nm is
directly proportional to?

A

hemoglobin concentration

28
Q

This cannot be converted to cyanmethemoglobin; it cannot be
measured.

A

Sulfhemoglobin

29
Q

This is the instrument used for Hemoglobin determination

A

Spectrophotometer

30
Q

The reagent used in Hemoglobin determination

A

Detergent-modified Drabkin’s reagent.

31
Q

Components of Drabkin’s reagent

A

Potassium Cyanide
Potassium Ferricyanide
Potassium dihydrogen phosphate or sodium bicarbonate
Non-ionic compound (improves cell lysis)

32
Q

Potassium ferricyanide:

A

hemoglobin → methemoglobin

33
Q

Potassium cyanide:

A

methemoglobin → cyanmethemoglobin

34
Q

The anticoagulant used for Hgb determination

A

EDTA or Heparin

35
Q

These are resistant to hemolysis, causing turbidity

A

Cells containing Hb S and Hb C

36
Q

This hemoglobin takes 1 hour to convert to cyanmethemoglobin and theoretically could cause erroneous results in samples from heavy smokers

A

Carboxyhemoglobin

37
Q

Why do need to be cautious with the hemoglobin reagent?

A

Because it contains cyanide, which is
highly toxic. Acidification of cyanide in the reagent releases highly toxic hydrogen cyanide gas

38
Q

The ratio for reagent to blood in Hgb determination

A

5 ml or 5000 ul of reagent, 20 ul or 0.02 ml of whole blood.

39
Q

Normal Hemoglobin values

A

Male: 14-18 g/dL
Female: 12-15 g/dL
Newborn: 16.5-21.5 g/dL

40
Q

Technical sources of errors for Hgb determination

A

Pipetting errors
Dirty and scratch cuvettes
Deteriorated reagent

41
Q

Biologic sources of errors for Hgb determination

A

Lipemic Sample
Leukocytosis
Hgb S and Hgb C

42
Q

Refers to the volume of packed red blood cells that occupy a given volume of whole blood.

A

Hematocrit

43
Q

Hematocrit is often referred
to as

A

packed cell volume (PCV)

44
Q

It is reported either as a percentage (e.g., 36%) or in liters per liter (0.36 L/L).

A

Hematocrit

45
Q

Anticoagulant used for microhematocrit

A

EDTA or heparin

46
Q

Two methods for hematocrit testing

A

Macrohematocrit (uses wintrobe tube)
Microhematocrit (uses capillary tube)

47
Q

Normal Hematocrit values

A
  • Male 40-54% (0.40-0.54 L/L)
  • Female 35-49% (0.35-0.49 L/L)
  • Newborn 53-65% (0.53-0.65 L/L)
  • Child 30-43% (0.30-0.43 L/L)
48
Q

The instrument used to determine hematocrit

A

microhematocrit reader

49
Q

What are the four layers in a hematocrit tube?

A

Plasma, buffy coat (WBCs & platelets), and RBCs

50
Q

The length of the sealing clay

A

at least 4 mm long

51
Q

When loading the micro hematocrit centrifuge, the clay ends must be facing the _____ from the center, touching
the rubber gasket

A

outside away

52
Q

How many minutes should you centrifuge the capillary tubes?

A

Centrifuge the tubes for 5 minutes between the speed of 10,000 g to 15,000 g

53
Q

Factors that cause a false decrease in hematocrit

A

-Incomplete sealing of tubes
-Hemolysis
-Over Anticoagulated Blood
-Introduction of interstitial fluid from a skin puncture or the improper flushing of an intravenous catheter

54
Q

Factors that cause a false increase in hematocrit

A

-Reading including the buffy coat
-Inadequate centrifugation
-Abnormal RBC Morphology: Macrocytic -Anemia, Spherocytosis, Thalassemia, Hypochromic Anemia, Sickle Cell Anemia
-Fluid loss associated with dehydration

Hematology Lab (4 decks)

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