Hematocrit Flashcards
(25 cards)
Besides evaluating RBCs, the HCT also screens for which 2 condition?
- anemia
- polycythemia
This is one of several lab tests available to evaluate RBC’s?
The hematocrit
The hematocrit value represents the percentage of what?
the volume of whole blood which is composed of red blood cells
T/F: Since the HCT is directly related to the volume of the red blood cells, it is affected by the size of the individual RBC’s themselves.
True
HCT values must always be evaluated in conjunction with which type of values?
MCV values
An individual with microcytic anemia will have relatively _______ HCT value, whereas macrocytosis will result in a _________ value
lower; higher
Since macrocytosis can artificially elevate hematocrit values, it may mask which condition?
anemia
Blood volume will __________ in cases of severe dehydration, resulting in _________ HCT values.
decrease; increased
HCT typically ___________ in pregnancy, especially during the second trimester. Why?
decreases; Hemodilution occurs as a woman’s body dramatically increases total blood volume in a short period of time.
In the case of acute hemorrhage, the HCT value will do what initially? Why? As an individual recovers, and increases their blood volume, the HCT will do what?
remain normal
The total volume of blood is decreased, so relative volume of the RBC’s remains the same, even though there has been a great loss of RBC’s.
drop significantly
What are normal HCT values ranges for women?
36 to 48%
What are normal HCT values ranges for men?
42 to 52%
What are normal HCT values ranges for newborns? Why?
Newborns have many macrocytic cells, so they have the highest norms, 44-64%.
After 60 years old, both men and women typically produce ________ amounts of RBC’s, and so their HCT values may ________.
lower; decline
After you collect blood in EDTA, lavender top, tubes why should you be sure to invert the tubes several times after drawing?
to ensure proper mixing of the blood and anticoagulant
How full would you fill capillary tubes of well mixed blood?
2/3 to 3/4 full
Load the tubes into the microhematocrit centrifuge in which configuration? Which direction should the clay ends be facing?
opposite one another; with the sealed ends pointing towards the outside of the centrifuge
What is a very important security protocol after the capillary tubes are in place prior to turning on the centrifuge?
Secure the tube restraining device over the tubes!!!
How long should the blood be centrifuged?
5 minutes
Where should the top and bottom of the blood in the capillary tubes line up with?
Line up the bottom of the column of blood with the bottom red line (0 %) on the card
Slide the tube along the card until the top of the sample column lines up with the red 100% line on the card
What portion of the capillary tube determines HCT? What should NOT be included when taking this reading?
Plasma/ RBC junction
Be sure not to include the “buffy layer” in your reading- this is the small clear layer directly above the RBC’s and is composed of WBC’s and platelets
Prolonged venous stasis due to the tourniquet being left on for too long will result in which type of error?
a falsely elevated HCT value
Failure to adequately mix the blood in the tube immediately after drawing may result in which type of error? How many inversions are required?
a falsely depressed HCT value
8 inversions required
Including the buffy coat in the reading may produce which type of error?
increase HCT reading
