HCT, ESR, OFT Flashcards
Hematocrit
pertains to the instrument used to determine packed cell volume [PCV]
volume of the red blood cells that have settled
packed cell volume/hematocrit
hematocrit
object being seen in a diff. position by changing the position of the head of the observer, or as seen by one
eye versus the other eye
-Micro-Hematocrit Tube
o Approx. 75 mm long
o Inner bore: 1 .2 mm
o Can hold 0.05 mL of bld.
o Plug: 4 to 6 mm long
-Micro-Hematocrit Tube 2 TYPES:
1) Red band
2) blue band
no anticoagulant
blue band
with anticoagulant
red band
fill microhematocrit tube up to
2/3
top layer
fatty layer
4th layer
packed rbc
2nd layer
plasma layer
3rd layer
buffy coat
5th & 6th layer
wax and clay
microhematocrit spins for ____ at _____
5 minutes at 10,000 RPM
2 patient samples run must agree within
+/- 0.02 L/L
Trapped plasma may cause the Hct to
falsely increased (0.02 L/L)
a calculated value from RBC and MC
Automated hematocrit
More trapped plasma in the following:
-Sickle cell anemia Hypochromic anemia Spherocytosis Macrocytosis Thalassemia
Some of the causes of
Falsel
1) DEHYDRATION
2) Hemoconcentration
3) insufficient centrifugation
4) buffy coat inclusion in the reading
Falsely DECREASED Hematocrit
1) hemolysis
2) improper sealing of capillary tube
3) inc. anticoagulation conc.
3) introduction of interstitial fluid
used for checking validity of test results
RULE OF THREE
rule of three can only be done on
normocytic, normochromic specimens
RULE OF THREE formula
3 x RBC = Hgb
3 x Hgb = Hct (+/- 3%)
ERYTHROCYTE INDICES
1) MCV
2) MCH
3) MCHC
Average volume of an individual RBC
MCV
MCV FORMULA
MCV = (Hct / RBC count) x 10
MCV Normal value
80 to 100 femtoliters
Average weight or amount of hemoglobin in an individual RBC
MCH
MCH follows the
MCV
MCH FORMULA
MCH = (Hgb x RBC ct.) x 10
MCH NV
26 to 32 picograms
Mean concentration of hemoglobin in the average RBC
Mean Cell Hemoglobin Concentration (MCHC)
MCHC Formula
MCHC = (Hgb / Hct) x 100
MCHC NV
31 to 37 g/dL or %
MCHC true increase is only seen
Hereditary spherocytosis
Value true increase of MCHC
35 - 38 g/dL
CLASSICALLY defined as increased hematocrit level above norma
POLYCYTHEMIA
Absolute polycythemia
elevated total red cell mass
Relative polycythemia:
normal total red cell mass, but hematocrit is increased because plasma volume
is decreased
P O L Y C Y T H E M I
(mutated VHL gene)
Chuvash polycythemia
*POLYCYTHEMIA VERA aka
Polycythemia Rubra
Vera
Polycythemia Vera
panmyelosis
hallmark sign of PV
Plethroa
mutation in _____ - PV
JAK2 V617F
ERYTHROCYTE SEDIMENTATION RATE
Rate of fall of RBCs settling to the bottom of the tube
ESR is for detecting and monitoring
inflammatory conditions
ESR > 37 mm/h
prostate cancer
ESR of > 28 mm/h
stroke
ESR >22 mm/h
coronary artery disease
Methods of ESR Determination
1) Westergren
2) Modified Westergren
3) Wintrobe
4) VES-MATIC 20 Instrument
stages of RBC sedimentation
1) Lag phase
2) decantation phase
3) final settling phase
last 10 mins (esr)
final settling phase
next 40 mins
decantation phase
first 10 mins
Lag phase
“A tilt of as little as 3’
cause error of up to
30%.”
anticoag in OFT
heparin