LABORATORY EVALUATION Flashcards
is the volume of packed RBCs that occupies
a given volume of whole blood.
hematocrit
Macromethods
- Wintrobe Method
- Haden’s Modification Method
- Van Allen’s Method
- Sanford – Magath Method
- Bray’s Method
1.1% Na citrate
Haden’s modification method
Heparin
Bray’s Method
1.3% NA citrate
Sanford - Magath Method
Double oxalate
Wintrobe Method
Anticoagulated whole blood is centrifuged, and
the total volume of the red cell mass is
expressed as a percentage or a decimal
fraction
hematocrit
normal value of hematocrit in women
35 % - 49 %
normal value of hematocrit in men
42 % - 54 %
Clinical Implication
- Decreased values are indicator of anemia
- Hct may or may not be reliable immediately after
even a moderate loss of blood or immediate
transfusion
Increased Hct values occur in
⚫Erythrocytosis
⚫Polycythemia vera
⚫Shock , when hemocentration rise
considererably
Interfering Factors
⚫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
composed of two raised surfaces each in the shape of a
3-mm x 3-mm square separated by an H-shaped moat
Hemocytometry
represents the number of WBCs in 1 liter of whole blood
WBC count
unit for WBC ct
10^9/L
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 ct:
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
RBC ct formula
RBC Count = # of cells counted x area c.f. x depth c.f. x dilution factor
unit for RBC ct
10¹²/L
Reference Range for RBC ct:
Male: 4.6-6.0 x 10ˈ²/L
Female: 4.0-5.4 x 10ˈ²/L