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AMT MLS Exam - Hematology > Hematology - RBC ref ranges & indices > Flashcards

Hematology - RBC ref ranges & indices Flashcards

1
Q

What is the composition of whole blood?

A

RBCs, WBCs, Platelets, and Plasma

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2
Q

After centrifugation of whole blood, what does the buffy coat consist of?

A

WBCs and Platelets

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3
Q

What is the difference between plasma and serum?

A

Plasma - liquid portion of UNCLOTTED blood

Serum - liquid portion of CLOTTED blood

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4
Q

Does serum contain all coagulation proteins?

A

No, it lacks the fibrinogen group

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5
Q

Does plasma contain all coagulation proteins?

A

Yes

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6
Q

Describe the appearance of plasma.

A

hazy and pale yellow

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7
Q

Describe the appearance of serum.

A

clear and straw colored

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8
Q

What is the formula for calculating MCV?

A
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9
Q

What is the reference range for MCV?

A

80-100 fL

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10
Q

What does MCV measure?

A

the average/mean volume of RBCs (and size of RBCs)

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11
Q

What conditions is MCV INCREASED in?

A
  1. megaloblastic anemia
  2. hemolytic anemia with reticulocytosis
  3. liver disease

Note: normal in newborn.

macrocytic anemias

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12
Q

What conditions is MCV DECREASED in?

A
  1. iron deficiency anemia
  2. thalassemia
  3. sideroblastic anemia
  4. lead poisoning

microcytic anemias

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13
Q

Is MCV calculated or directly measured by automation?

A

directly measured by automation

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14
Q

What is the formula for MCH?

A
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15
Q

What is the reference range for MCH?

A

27-31 pg (pictograms)

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16
Q

What does MCH measure?

A

the average weight of hemoglobin in individual RBCs

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17
Q

What conditions is MCH INCREASED in?

A

macrocytic anemias

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18
Q

What conditions is MCH DECREASED in?

A

microcytic anemias

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19
Q

What RBC indices parallel MCV?

A

MCH

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20
Q

What is the formula for calculating MCHC?

A
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21
Q

What is the reference range for MCHC?

A

32-36% or g/dL

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22
Q

What is MCHC a measure of?

A

the average concentration of hemoglobin

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23
Q

What conditions is MCHC INCREASED in?

A
  1. presence of spherocytes
  2. error in RBC or HGB measurement
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24
Q

What conditions is MCHC DECREASED in?

A
  1. iron deficiency
  2. thalassemia

hypochromic RBCs

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25
Q

What is the reference range for RDW?

A

11.5-14.5%

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26
Q

What is RDW determined by?

A

the RBC histogram

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27
Q

What is the RDW increased in proportion to?

A

the degree of anisocytosis (variation in size)

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28
Q

What conditions is a high RDW seen in?

A
  1. post-transfusion
  2. post-treatment (e.g., B12, folic acid, iron therapy)
  3. idiopathic sideroblastic anemia
  4. in presence of 2 concurrent deficiencies (iron and folic acid deficiency)
29
Q

What does the RDW help to identify?

A

anisocytosis

30
Q

What is the normal hematocrit for a male?

A

40-54% (0.40-0.54 L/L)

31
Q

What is the normal hematocrit for a female?

A

35-49% (0.35-0.49 L/L)

32
Q

What id the normal hematocrit for a newborn?

A

48-68% (0.48-0.68 L/L)

33
Q

Is the buffy coat included in the measurement of hematocrit?

A

no

34
Q

What is the calculation for the hematocrit?

A

Hct (%) = (MCV x RBC)/10

35
Q

What is PCV?

A

packed cell volume - another name for hematocrit
-it is the ratio of the volume of RBCs to the volume of whole blood

36
Q

How do the spun hematocrit (manual) and the hematocrit derived from an automated cell counter differ?

A

-the automated hct is derived from the RBC and MCV, therefore it may be lower than the spun hematocrit in which there is always some trapping of plasma within the RBC column
-the difference is negligible unless there is a great deal of poikilocytosis and anisocytosis

37
Q

What is the usual time and speed of centrifugation for a microhematocrit?

A

10,000 RPM for 5 minutes

38
Q

How would a microhematocrit result be affected by centrifugation speeds and times that are lower than 10,000 RPM for 5 minutes?

A

-lower speeds or times leads to inadequate packing of the RBCs and a falsely elevated hematocrit

39
Q

While performing a manual hematocrit, the technologist observes an increased buffy coat. What is the significance of this observation?

A

-the patient has an elevated WBC or extremely elevated platelet count
-the buffy coat should not be included in the measurement of the RBC column or the hematocrit will be falsely elevated

40
Q

While reading a manual hematocrit a technician observes that the plasma is pink. How would this affect the hematocrit?

A

Hemolysis of the RBCs decreases the hematocrit.

41
Q

A phlebotomist had a difficult time obtaining blood from a patient and was only able to fill the EDTA tube 1/4 full. How would this affect the hematocrit?

A

-automated hct - probably not affected

-microhematocrit - falsely decreased because the RBCs would be crenated by the excess anticoagulant

42
Q

How does excess anticoagulant affect platelets?

A

it breaks them up which would cause a false increase in the platelet count

43
Q

How does excess anticoagulant affect WBCs?

A

causes degenerative changes

44
Q

A new phlebotomist had difficulty finding a vein in a patient and the tourniquet was left on for 3 minutes before the blood was obtained. How would this affect the hematocrit?

A

It would be elevated due to hemoconconcentration.

45
Q

Which of the RBC indices is considered the most clinically useful?

A

MCV - it indicates the average size of the RBCs and is useful in the classification of anemias

46
Q

Calculate the MCV, MCH, and MCHC for the following specimen. How should the RBCs appear on the blood smear?

RBC: 3.0 x 10^12/L
HGB: 6 g/dL
HCT: 20%

A

MCV = 67 fL
MCH = 20 pg
MCHC = 30 g/dL

The RBCs would appear microcytic (low MCV) and slightly hypochromic (MCHC).

47
Q

What is the only clinical significance of a high MCHC?

A

hereditary spherocytosis

48
Q

What is MCHC useful as an indicator of?

A

the presence of an interfering factor in the specimen (e.g., hemolysis, cold agglutinins)

49
Q

A patient’s MCHC is reported as 37%. What abnormality should be looked for on the peripheral blood smear?

A

spherocytes

-if spherocytes are not present, one or more the RBC parameters may be incorrect

50
Q

A patient’s MCHC is reported as 30%. What abnormality should be looked for on the peripheral blood smear?

A

hypochromic RBCs

-if hypochromic RBCs are not seen on the smear, one or more of the RBC parameters may be incorrect

51
Q

What abnormality would be expected on the blood film when the MCV is high?

A

macrocytes

52
Q

Explain how a blood sample can have a normal MCV when marked anisocytosis is observed on the blood smear.

A

MCV is an average - it can be normal when there is a combination of macrocytes and microcytes

-the RDW would be INCREASED

53
Q

What abnormality would be expected on the blood film when the MCHC is low?

A

hypochromic RBCs

54
Q

What is the “rule of three”?

A

QC check for RBC parameters of the CBC

55
Q

What should one do if CBC values obtained do not follow the “rule of three”?

A
  1. check for abnormal RBC morphology on the blood smear
  2. check for specimen problem (e.g., lipemia, cold agglutinins)
  3. check for instrument error
56
Q

What is the adult male reference range for hemoglobin?

A

14-18 g/dL (140-180 g/L)

57
Q

What is the adult female reference range for hemoglobin?

A

12-15 g/dL (120-150 g/L)

58
Q

A patient has a hemoglobin of 12.3 g/dL. What is the expected range for the patient’s hematocrit?

A

36.9 +/-3

59
Q

What is the reference range for platelets?

A

150-450 x 10^3/uL (150-450 x 10^9/L)

60
Q

What is the reference range for MPV (mean platelet volume)?

A

6.8-10.2 fL

61
Q

What is the adult reference range for WBC count?

A

4.5-11.5 x 10^3/uL (4.5-11.5 x 10^9/L)

62
Q

What is the adult male reference range for RBC count?

A

4.6-6.0 x 10^6/uL
(4.6-6.0 x 10^12/L)

63
Q

What is the adult female reference range for RBC count?

A

4-5.4 x 10^6/uL
(4-5.4 x 10^12/L)

64
Q

Relative count vs. Absolute count

A

-relative count - the amount of a cell type in relation to other blood components

-absolute count - the actual number of each cell type without respect to other blood components

65
Q

What is relative lymphocytosis?

A

an increase in the % of lymphocytes (often associated with neutropenia)

66
Q

What is relative polycythemia?

A

RBCS appear increased due to decreased plasma volume

67
Q

What is absolute lymphocytosis?

A

a true increase in the number of lymphocytes

68
Q

What is absolute polycythemia?

A

a true increase in red cell mass

AMT MLS Exam - Hematology (6 decks)

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