MODULE 4 UNIT 1 Flashcards
Measurement of the Hematocrit may be done by the process of centrifugation with (?), or as the product of the mean corpuscular volume (MCV) multiplied by the RBC count (HCT% = [RBC × MCV] ÷ 10) indirectly in automated instruments.
macromethods or micromethods
In some instances, swelling of erythrocytes between (?) may raise Hematocrit and MCV when blood is kept at room temperature.
6 and 24 hours
However, for (?) cell counts and RBC indices are stable.
24 hours at 4° C
The number of inversions required to achieve (?) of a specimen depends on the dimensions of the container.
homogeneity
Standard 10–14 × 75-mm tubes, containing 5 mL of blood and an air bubble that constitutes at least (?) of the tube volume, require at least eight inversions.
20%
The (?) agrees closely with the Hematocrit obtained from a skin puncture; both are greater than the total body Hematocrit.
venous Hematocrit
The hematocrit is often referred to as the (?) , it is the volume of packed red blood cells that occupies a given volume of whole blood.
packed cell volume (PCV)
The manner of reporting the hematocrit is either as a (?).
percentage or in liters per liter
A thick-walled 11.5cm glass tube (?) is used for both ESR and Hematocrit determination with a uniform 3mm internal bore and a flattened bottom but is no longer used.
Wintrobe
Speed of Centrifugation in Macromethod:
2000 - 2300g for 30 minutes
Double Oxalate
Wintrobe and Landsberg
Sodium Oxalate
Van Allen
Haden
Sanford-Magath
Heparin
Bray
A (?) will be filled by a capillary punctured free-flowing blood or a wellmixed venous sample.
microhematocrit tube
Speed of Centrifugation in Micromethod:
10,000 - 15,000 for 5 minutes
Capillary tube in Micromethod:
Heparinized Capillary tube
Length in Micromethod:
7-7.5cm/ 70-75mm
Bore in Micromethod:
1mm/1.2mm
• at least (?) of the capillary tube should be filled.
5 cm
• The empty end of the capillary tube is sealed with (?).
modeling clay
• The filled tube is placed in the (?) of the microhematocrit centrifuge head with the sealed end away from the center.
radial grooves
Take note that additional (?) should be done if the Hematocrit exceeds 50%. This is to ensure less or minimal plasma trapping.
5 minutes centrifugation
: amount of plasma that still remains in RBC portion after the microhematocrit has been spun.
Trapped plasma
(?) is observed in patients with macrocytic anemias, Spherocytosis, Thalassemia, Hypochromic anemia and Sickle cell anemia.
Increase trapped plasma
accounts for about (?) of the red cell column in normal blood (about 0.014 in a Hematocrit of 0.47), slightly more in macrocytic anemia, spherocytosis, and hypochromic anemia (Dacie, 1991).
1%–3%
Greater amounts of trapped plasma are noted in the (?) of patients with sickle cell anemia; these may vary depending on the degree of sickling and consequent rigidity of the cells.
Hematocrits
In using the (?) as a reference method for calibrating automated instruments, correction for trapped plasma is recommended
microhematocrit
(?) is performed by centrifugation. Inspection of the specimen after spinning may furnish valuable information. The relative heights of the red cell column, buffy coat, and plasma column should be noted.
Hematocrit determination
The (?) is the red-gray layer between the red cells and the plasma; This is the layer that includes platelets and leukocytes.
buffy coat
An increase in (?) is suspected in orange or green color of the plasma, and pink or red suggests hemoglobinemia
bilirubin
Poor technique in collecting the blood specimen is the most frequent cause of (?).
hemolysis
Delayed specimen and/or are not obtained within an hour or two after a fat-rich meal, a cloudy plasma may point to nephrosis or certain abnormal hyperglobulinemia, especially (?).
cryoglobulinemia
Typical reference/normal values:
➢ At birth: (?)
0.45-0.60
Typical reference/normal values:
➢ for adult males are (?)
0.41–0.51
Typical reference/normal values:
➢ females: (?)
0.36–0.45
A value below an individual’s normal value or below the reference interval for age and sex indicates (1), and a higher value, (2).
- anemia
- polycythemia
The Hematocrit reflects the (?) and not the total red cell mass.
• Slight decrease is noted among individual with (?) of age and above.
50 years
• (?) is decrease among individual with Anemia
Hematocrit/ Packed Red Cell Volume
• Increase level of Hematocrit/Packed Red Cell Volume is noted among individual with (?)
Polycythemia
Hematocrit is low in hydremia of (?), but the total number of circulating red cells is not reduced.
pregnancy
(?) may also be normal or even high in shock accompanied by hemoconcentration, although the total red cell mass may be decreased considerably owing to blood loss.
HCT
• after loss of blood or immediately following transfusion maybe (?) as an estimate of anemia.
unreliable
3 Sources of Error:
Centrifugation
Sample
Other Errors
Adequate duration and speed of (?) are essential for a correct Hematocrit.
centrifugation
The red cells must be (?) so that additional centrifugation does not further reduce the packed cell volume.
packed
In the course of centrifugation, small proportions of the (?) are trapped between the red cells.
leukocytes, platelets, and plasma
The (?) resulting from the former is, as a rule, quite insignificant.
error
The (?) is larger in high Hematocrits than in low Hematocrits.
amount of trapped plasma
(?) can cause the same order of changes in Hematocrit and cell concentrations as they do in nonfilterable soluble constituents.
Posture, muscular activity, and prolonged tourniquet-stasis
However, excessive or inadequate concentration of (?) may cause erroneous interpretation of result.
anticoagulant
Technical errors include failure to mix the blood adequately before sampling, improper reading of the levels of cells and plasma, and inclusion of the buffy coat as part of the (?).
erythrocyte volume
With good technique, the precision of the Hematocrit, expressed as (?), is ±1%.
±2 CV (coefficient of variation)
With low Hematocrit values, the (?) is greater because of reading error.
CV
Hematocrit can be done by applying the “(?)”
rule of three
This rule applies only to samples that have normocytic normochromic red blood cells.
Rule of Three
The value of the hematocrit should be (?) the value of the hemoglobin plus or minus 3: HGB X 3 = HCT +/- 3 (0.03 L/L).
three times
It should become habit for the analyst to multiply the hemoglobin by (?) mentally for every sample; a value discrepant with this rule may indicate abnormal red blood cells, or it may be the first indication of error.
3
HGB= 11 g/dL
HCT= 36% (0.36 L/L)
According to the rule of three, HGB (11) X 3 = HCT (33)
The acceptable range for the hematocrit would be (?) These values followed the rule of three.
33% to 36%.
Case 2:
HGB= 8 g/dL
HCT= 32%
According to the rule of three, HGB (8.0) X 3 = HCT (24 versus actual value of 32). In this case, the acceptable range for hematocrit would be (?) . These ranged obtained did not meet the rule of three.
24% to 30%
Insufficient centrifugation will result in:
A false increase in hematocrit value
Which of the following calculated values will not be affected in a falsely elevated Hematocrit?
MCH
Hematocrit Determination refers to:
the percentage of red blood cells in a sample of whole blood.
If your bone marrow is producing an elevated number of red blood cells, what happens to your hematocrit?
The hematocrit value increases.
Which of the following statements is Incorrect?
A. The amount of plasma that still remains in RBC portion after the microhematocrit has been spun should be taken into consideration.
B. Poor technique in collecting the blood specimen is the most frequent cause of hemolysis.
C. Greater amounts of trapped plasma are noted in the Hematocrits of patients with sickle cell anemia
D. The red-gray layer between the red cells and the plasma; This is the layer that includes platelets and leukocytes is known as the Trapped Plasma.
A. The amount of plasma that still remains in RBC portion after the microhematocrit has been spun should be taken into consideration.
Case 1:
HGB= 13 g/dL
HCT= 38%
According to the rule of three, HGB (13) X 3 = HCT (39)
The acceptable range for the hematocrit would be (?). These values meet the rule of three
36% to 42%
Case 2: Try to compute for the possible HCT values using the Rule of Three
HGB= 10 g/dL
HCT=?
According to the rule of three, HGB (13) X 3 = HCT (30)
HCT = 30
The acceptable range for the hematocrit would be (?). These values meet the rule of three
27% to 33%
Case 3: Now, try to compute for the possible HGB and HCT values using the Rule of Three RBC Count: 4.7x10^12/L
HGB=?
HCT=?
RBC X 3 = HGB
HGB X 3 = HCT
4.7 X 3 = 14.1 (HGB)
According to the rule of three, HGB (14.1) X 3 = HCT (42.3)
The acceptable range for the hematocrit would be (?). These values meet the rule of three
39.3% to 45.3%
CASE 4.
Patient’s result:
RBC: 4.49
WBC: 3.4
HGB: 12.0
HCT: ____
MCV: 99.4
MCH: 35.9
MCHC: 36.1
PLT: 95
RDW: 19.5
A. Compute for the Hematocrit value:
(1)
Interpret the result:
(2)
- (RBC)(MCV)/10
= (4.49)(99.4)/10
= 44.63 - The hematocrit value is within the normal reference range
CASE 4.
Patient’s result:
RBC: 4.49
WBC: 3.4
HGB: 12.0
HCT: ____
MCV: 99.4
MCH: 35.9
MCHC: 36.1
PLT: 95
RDW: 19.5
B. Compute for the HCT using the Rule of Three:
(1)
Acceptable range:
(2)
- HGB (12) X 3 = HCT (36)
- The acceptable range for the hematocrit would be 33% to 39%. These values meet the rule of three
CASE 5
Patient’s result:
RBC: 4.33
WBC: 3.4
HGB: 12.5
HCT: ____
MCV: 90.4
MCH: 36.9
MCHC: 33.1
PLT: 125
RDW: 20.5
A. Compute for the Hematocrit value:
(1)
Interpret the result:
(2)
- (RBC)(MCV)/10
= (4.33)(90.4)/10
= 39.14 - The hematocrit value is within the normal reference range
CASE 5
Patient’s result:
RBC: 4.33
WBC: 3.4
HGB: 12.5
HCT: ____
MCV: 90.4
MCH: 36.9
MCHC: 33.1
PLT: 125
RDW: 20.5
B. Compute for the HCT using the Rule of Three:
(1)
Acceptable range:
(2)
- HGB (12.5) X 3 = HCT (37.5)
- The acceptable range for the hematocrit would be 34.5% to 40.5%. These values meet the rule of three
CASE 6
Patient’s result:
RBC: 4.0
WBC: 3.4
HGB: ____
HCT: ____
MCV: 93.4
MCH: 32.9
MCHC: 36.1
PLT: 112
RDW: 21.5
Compute for the possible HGB and HCT using the Rule of Three:
HGB:
(1)
HCT:
(2)
Acceptable range:
(3)
- HGB = RBC X 3
HGB = 4.0 X 3
HGB = 12 - HGB (12) X 3 = HCT (36)
- The acceptable range for the hematocrit would be 33% to 39%. These values meet the rule of three.
