midterm - LABORATORY EVALUATION Flashcards
3 layers formed in hematocrit
buffy coat
plasma
rbc
sealant parts
wax and clay
a measure of Packed Cell Volume (PCV)
Hematocrit
is the volume of packed RBCs that occupies
a given volume of whole blood
Hematocrit (Hct)
principle of hematocrit
Anticoagulated whole blood is centrifuged, and the total volume of the red cell mass is
expressed as a percentage or a decimal
fraction
manner of reporing for hematocrit
decimal L/L or percentage
Methods of Hematocrit Determination
- Wintrobe Method
⚫Double oxalate
2.Haden’s Modification Method
⚫1.1% Na citrate
3.Van Allen’s Method
⚫1.6% Na citrate - Sanford – Magath Method
⚫ 1.3% NA citrate - Bray’s Method
⚫ Heparin
method of collection of macrohematocrit
venipuncture
method of collection of microhematocrit
skin puncture
amount of blood for macrohematocrit
larger
amount of blood for microhematocrit
smaller
rcf for macrohematocrit
2000 to 2300 rpm
rcf for microhematocrit
10 000 - 12 000 rpm
time of centrifugation for macrohematocrit
longer 30 mns
time of centrifugation for microhematocrit
shorter 3-5 mns
can we perform esr in microhematocrit
nope, only in macro
spilling and leakage for macro
not common
spilling and leakage for micro
common
breakage of buffy coat in macro
not common
breakage of buffy coat in micro
common
separation of buffy coat in macro
complete
separation of buffy coat in micro
not complete
reference value for hematocrit
male - 42 - 54%
female - 35 - 49%
⚫Increased Hct values occur in
⚫Erythrocytosis
⚫Polycythemia vera
⚫Shock , when hemocentration rise
considererably
Decreased values are indicator of anemia
⚫Leukemia , lymphomas
⚫Adrenal insufficiency
⚫Chronic disease
⚫Acute and chronic blood loss
Hct may or may not be reliable immediately after even a moderate loss of blood or immediate
transfusion
true or false
true
Interfering Factors for hematocit
⚫High altitude
⚫NV vary with age and gender
⚫Lower value in men and women older than 60 y/o
⚫Severe dehydration from any cause falsely raises the hct
Sources of Error in Hematocrit Determination
- Speed and duration of centrifugation Decrease in centrifugal force will result in more trapped plasma in between red cells.
- Type and amount of anticoagulant
Excess anticoagulant causes shrinkage of cells - Integrity in the length and diameter of the tube
- Errors in the sample, improper techniques in the collection of venous and capillary blood.
- Failure to mix the blood properly before sampling
- Leakage of blood in the case of micro hematocrit.
- Errors in taking the reading and calculating the result.
the process of enumerating blood cells
Hemocytometry
capillary tube size
75 mm
filling the capillary tube for ___
3/4
is anemia a secondary condition?
yes
remaining in packed cell volume are called
trapped plasma - causing falsely increase in the hcv
total ruled area of hemacytometer
9 square meter
Macroscopically the hemacytometer is
3-mm x 3-mm square separated by an H-shaped moat
1 big square has a size of
1 mm
the 4 corner quadrants in the hemocytometer is for
wbc
the center quadrant is for
rbc and platelet
in 1 big square, how many squares do it have?
16
in the central square, how many squares it has?
25 squares
the distance between each counting surface and coverslip
(depth) is ___
0.10 mm
WBC Diluting Fluid
- 2-3% glacial acetic acid
- 1% HCl added with 1 drop of methyl violet or crystal violet
Criteria of Good WBC Diluting Fluid
- should be hypotonic
- should color/stain the nuclei of white blood cells
Reference Range for wbc counting
4.5-11.5 x 10⁹/L
WBC Count must be corrected if 5 or more NRBCs are counted
on differential count since NRBCs present in the sample are not
lysed by the diluting fluid and counted as WBC
Corrected WBC Count
represents the number of WBCs in 1 liter of whole blood
White Blood Cell Count
Reference Range: for rbc counting
Male: 4.6-6.0 x 10ˈ²/L
Female: 4.0-5.4 x 10ˈ²/L
RBC Diluting Fluids
- Hayem’s Fluid
- Gower’s Solution
- Toisson’s Fluid
- Dacie’s or Formol Citrate Solution
- Bethel’s Fluid
- NSS or Physiologic Salt Solution
- 3.8% Sodium Citrate
v this is considered the best diluent .
v It keeps for a long time and does not alter
the shape of the cells
for rbc diluting fluid
Dacies Fluid ( Formol Citrate)
composition of rbc diluting fluid dacies
40 % formaldehyde 10 ml
3% w/v disodium citrate 990 ml
Hayem’s Diluting Fluid composition
⚫ Mercuric chloride 1 g
⚫ Sodium Sulfate Anhydrous 4.4 g
Gower’s Solution- prevents rouleaux formationn composition
- Sodium sulfate anhydrous 12.5 g
- Glacial acetic acid 33.3 ml
- Distilled water 200 ml
an rbc diluent that is high specific gravity and stains the
WBC
toisson’s fluid
toisson’s fluid’s composition
-Na chloride 1.0 gram
- NaSo4 8.0 grams
Glycerin 30.0 grams
Methyl violet 0.25 grams
Distilled Water 180 ml
rbc diulent that is sed in emergency cases,
used in the presence of rouleaux formation and
autoagglutination of cells
Normal Saline Solution
Criteria of Good RBC Diluting Fluid
- Must be an isotonic solution
- Has a good preservative
- Does not initiate the growth of molds
and yeast - With a high specific gravity
- With buffer action
- Cheap and easy to prepare
40% formaldehde - 10 ml
preserve rbc
disodium citrate - 990 ml
prevent coagulation
Criteria of Good RBC Diluting Fluid
- Must be an isotonic solution
- Has a good preservative
- Does not initiate the growth of molds
and yeast - With a high specific gravity
- With buffer action
- Cheap and easy to prepare
the value of the hematocrit should be three times the value of
hemoglobin (+3)
Rule of Three
