Chap 11 Flashcards
Manual Testing in Hematology
What anticoagulant is used in the hematology lab?
Ethylenediaminetetraacetic Acid (EDTA)
How long can a CBC be stored at room temp before analysis should be done?
6hrs
If we needed to store the sample for 24hrs, what temp should it be stored at?
4 degrees Celcius
Within what time frame should PB smears be made?
Within 3 hrs of collection
Why do PB smears need to be made w/n 3 hrs?
To reduce cell deterioration and morph artifacts.
When looking at the grid of a hemacytometer, which squares are counted for WBCs?
The 4 corners, each of the corners has 16 squares.
When looking at the grid of a hemacytometer, which squares are counted for RBCs
The 4 corners and middle square of the middle big square. (make it make sense)
What is the dilution fluid used when doing a manual WBC or PLT count?
1% buffered Ammonium oxalate or if just counting WBCs, a weak acid solution (3% acetic acid or 1% hydrochloric acid) can be used.
Typical dilution for WBC count?
1:20, unless PLTs need counted as well, then 1:100.
What are the parts of dilution for manual WBC count?
1 part, 25uL of well-mixed blood to 1part of 475uL of diluting fluid.
How long does a hemacytometer sit after being charged and why?
Sets for 10min to allow the cells time to settle.
Cells touching the top and left side lines on a hemacytometer are counted? (T or F)
True
Cells touching the bottom and right side lines on a hemacytometer are counted in the box your currently counting? (T or F)
False
Typical dilution for a manual PLT count on a hemacytometer? Dilution Fluid?
1:100 W/ 1% ammonium oxalate
Where on a hemacytometer do we count PLTs?
All 25 squares of the big middle square.
To count RBCs on the hemacytometer, what kind of diluting fluid is used?
Isotonic Saline
What is the dilution for a manual RBC count on the hemacytometer?
1:100
The ________number of cells on the 2 slides is used to calculate the WBCs.
Average
The WBC calculation is?
Cells Counted x Dilution Factor/
# of square counted x the depth
WBC Calculation example
Calculate
96 cells, 20 dilution factor (DF), 4 sq counted, and 0.1 depth?
96 (cells) x 20 (DF)
Divided by
4 (sq counted) x 0.1 (depth)
96x20x10/4= 4800/mm cubed
4.8x10^3/uL
What is the 1:100 dilution for a PLT count on a hemacytometer?
20uL of well-mixed blood into 1980uL of 1% ammonium oxalate.
What makes manual RBC counts so rare?
Inaccuracy of the count and questionable necessity.
What power do we count each cell type on?
WBCs- 10x (100x W/ ocular and obj.)
RBCs-40x (400x W/ ocular and obj.)
PLTs-40x (400x W/ ocular and obj.)
Principle of the cyanmethhemoglobin assay to determine Hgb?
Blood in an alkaline Drabkin solution, (potassium ferricyanide, potassium cyanide, sodium bicarbonate, and a surfactant). Hgb is oxidized to met-Hgb (Fe3+) by the potassium ferricyanide, K3Fe(CN)6. The potassium cyanide (KCN) then converts the met-Hgb to cyanmet-Hgb.
What wavelength should the spectrophotometer be set at for the Cyanmethemoglobin assay?
540nm
When performing a microhematocrit, what speed should the centrifuge be set at?
10,000-15,000g
Before centrifuging a specimen for a microhematocrit, what must be placed in the end?
Non-absorbent clay
When attempting to measure and read the hematocrit using a microhematocrit, what do you avoid?
Including the buffy coat
Rule of 3?
Hgb x 3 = Hct (+/- 3)
RBC x 3 = Hgb
RBC x 9 = Hct
What can cause the rule of 3 to not correlate the data?
Red cells are abnormal (not normochromic, normocytic).
MCV
Hct x 10/ RBC = (fL)
MCH
Hgb x 10/RBC = (pg)
MCHC
Hgb x 100/Hct = (%)
MCV reference range
80.0-100.0 fL
Newborn MCV reference range
95.0-125.0 fL
Children MCV reference range
76.0-92.0 fL
MCH Reference Range
26.0-34.0 pg
MCHC reference range
32.0-36.0% (or g/dL)
RDW reference range
11.5-14.5%
MCV<80fL, MCHC<32, Microcytic, Hypochromic?
IDA, Anemia of Inflammation, Thalassemias, Hb E Disease and trait, SA
MCV 80-100, MCHC 32-36, Normocytic, Normochromic?
Hemolytic Anemia, Myelophthisic Anemia, BM failure, Chronic Renal Disease
MCV >100, MCHC 32-36, Macrocytic, Normochromic?
Megaloblastic Anemia, Chronic liver disease (CLD), BM failure, Myelodysplastic Syndrome
Principle of manual Retic count?
Any NRBCs W/ 2 or more particles of blue granulofilamentous material after supravital stain new methylene blue are retics.
What stain do we use to stain retics?
Supravital stain New methylene blue(SPS and NMB)
How many drops of blood to how much NMB for a retic stain?
Equal parts
How long should the tube sit after blood and NMB have been added?
3-10 minutes (Closer to 10)
What should be done to improve Retic counts?
Have another laboratorian count the other film made and the counts should be within 20%.
How many wedge smears are made for a retic count?
2
Retic % calculation
of retics x 100/ 1000 RBCs counted
Retic % calculation Example:
15 (Retics) x 100/ 1000 (RBCs)
15 x 100/ 1000=
150/1000= 1.5%
Absolute Retic Calculation (ARC)
Retic % x RBC Count/ 100
ARC Example
Calculate
4.0% Retics in 1000 RBCs, 3.01 million RBCs
4.0 x 3,010,000/ 100=
12,040,000/100= 120,400 or 120.0x10^3/uL
What can cause an increased Retic count %?
Low Hematocrit
Corrected Retic Count (CRC) Calculation
CRC= Retic % x PT Hct %/ 45 (Normal Hct)
CRC Example
Calculate
Retic %- 5.5%, PT Hct- 24%
5.5% x 0.24/45=
1.32/45= 0.029 CRC %
Retic reference range
0.5-2.5% (Relative)
or
20,000-115,000/uL or 20-115x10^3/uL (Absolute)
Shift Retics
Retics that are released from the BM prematurely.
What can cause shift retics?
Anemia or RBC morph W/ polychromasia.
Retic Production Index (RPI)
Indicates the BM’s response
RPI Calculation
RPI= Retic % x (Hct %/45)/ Mature Time
or
RPI= CRC/Mature time
(When Retics have been corrected)
RPI Example
Calculate
7.8% Retics, Hct 30%, W/ polychromasia
Maturation time 2 days.
7.8%x(0.3/0.45)/ 2=
7.8x0.67/2= 2.613
RPI=2.6
RPI greater than 3 indicates?
Adequate BM response
RPI less than 2 indicates?
Inadequate Erythropoietic response
Erythrocyte Sedimentation Rate (ESR)
Ordered W/ other tests to detect and monitor course of Imflammatory conditions (I.E. RA, Infections, certain malignancies).
ESR is useful in diagnosing RA, but what other 2 arthritis diseases is it also helpful with?
Temporal Arteritis and Polymyalgia Rheumatica.
(T or F): ESR is a specific test for inflammatory diseases?
False, the ESR is elevated in many other conditions (I.E. Plasma cell myeloma, Pregnancy, Anemia, older age).
What test for inflammation may be more predictable and reliable than ESR?
C-reactive protein
ESR is?
the distance in mm that RBCs fall in 1 hr.
Male ESR reference range and males over 50?
0-15mm/hr
0-20mm/hr (>50)
Female ESR reference range and females over 50?
0-20mm/hr
0-30mm/hr (>50)