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UNIVERSITY OF MICHIGAN HEALTH SYSTEM
DEPARTMENT OF PATHOLOGY
POINT OF CARE SERVICES

HEMATOCRIT


PRINCIPLE:

The Packed Cell Volume Hematocrit is a measure of the ratio of the volume occupied by red blood cells to the volume of whole blood. It is expressed as a percentage. Whole blood in microhematocrit capillary tubes are subjected to sufficient centrifugal force to pack the red blood cells into as small a volume as possible and compare that volume to the volume of the entire sample. This ratio is the hematocrit.
If below normal, the hematocrit indicates anemia, and an above normal value may indicate polycythemia.

COMPUTER CODE: HCRT

SPECIMEN:
A fingerstick is used to collect whole blood in heparinized capillary tubes for the hematocrit measurement. The minimum volume is one capillary tube filled half way.

MATERIALS NEEDED:
• Heparinized capillary tubes (75mm self sealing)
• HemataSTAT-II centrifuge
• Mid level Meter Trax Control

STORAGE:
The centrifuge and heparinized capillary tubes can be stored at room temperature (15-30°C). It is critical that the cap be replaced on the self sealing capillary tubes after use. Moisture from the air could cause the plugs to seal prematurely and impair capillary action of the tube. Meter Trax control material must be stored refrigerated (2-8 °C), and is good for 31 days after opening.

QUALITY CONTROL:
Perform QC as indicated on the “QC log” using Meter Trax control material. Quality control will be performed a minimum of once per week or once each day a patient sample is performed, whichever is less.
Mix the Meter Trax control vigorously and perform a spun hematocrit using the HemataSTAT-II. Percent hematocrit must fall in the acceptable control range listed on the QC log, or the control needs to be repeated. The control is good for 31 days once opened, and must be stored refrigerated (2-8°C).

PROCEDURE:

1. Perform a fingerstick, and wipe away the first drop of blood.
2. Fill two self sealing heparinized capillary tubes at least half full with blood.
3 Place capillary tubes in carriers in the centrifuge, clay end down. Balance the rotation head by placing tubes in opposite carrier positions.
4. Close the centrifuge lid and lock the latch.
5. Press RUN to spin. The LCD will display a 60 second countdown and begin the spin cycle.
6. When the spin cycle ends, wait for the beep and then unlock the door.
7. Remove one capillary tube and place in the groove at the base of the LDC display, sealed end to the left.
8. Make sure the 1.1 tube size appears in the window of the LCD display.
9. Press ENTER.
10.. Move the slider along the tube and position the black line on the Clay/Red Cell interface. Press ENTER.
11. Move the slider to the Red Cell/Plasma interface. Align the black line in the middle of the red cell angle. Press ENTER.
12. Move the slider along the tube and position the black line on the Plasma/Air interface. Press ENTER.
13. The display will present the hematocrit result in percent.
14. Press ENTER to read another tube or RUN to return to the main menu.
15. Perform a hematocrit measurement on each tube collected. The results must match within two percentage points. Find the average; this is the reportable patient result.** If the measurements do not match, read the tubes again. If they still do not match, repeat the test.

**Reportable Range for HEMATOCRIT IS 16– 60 %
If results are outside of this limit, Pathology recommends that a specimen be drawn
and sent to the main laboratory for confirmation.
**Critical Value: Less than 18 %
Notify the physician immediately. Document who was notified, date and time of
notification, and your initials on the bench sheet.


NORMAL VALUES:**

AGE: HEMATOCRIT:
0-1 month 42 – 60 %
1-3 months 28 – 42 %
3 months – 5 years 34 –41 %
5-16 years 34 – 52 %
Adult 42 – 52 % (male)
37 – 47 % (female)

*Reportable Range for HEMATOCRIT IS 16 –60 %
If results are outside of this limit, Pathology recommends that a specimen be drawn
and sent to the main laboratory for confirmation. Do not report patient results outside of this
range.

**Critical Value: Less than 18 %
Notify the physician immediately. Document who was notified, date and time of
notification, and your initials on the bench sheet.


LIMITATIONS:

1. A hemolyzed or clotted sample will yield an inaccurate hematocrit.
2. Prolonged stasis caused by constriction with a tourniquet for longer than one minute may result in a falsely high hematocrit.
3. Hematocrit tubes that leak during the spin cycle will result in an inaccurate result.
4. Results of greater than 50% may have trapped plasma in the specimen and be incorrect.

MAINTENANCE:
Perform maintenance as needed. Clean and decontaminate the centrifuge lid, rotor, and bowl with a non corrosive detergent. Discard any broken or contaminated capillary holders.

TECHNICAL SERVICE:
1-800-777-6668

REFERENCES:
HemataSTAT-II Instruction Manual. Separation Technology, Inc. Altamonte Springs, Florida 10/99.





 

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