Document Number:
Pro64-C-02
Effective (or Post) Date:
23 Jan-09
Review History
Date of last review:
Na
Reviewed by:
Heidi Hanes
SMILE Comments: This document is provided as an example only. It must be revised to accurately reflect
your lab’s specific processes and/or specific protocol requirements. Users are directed to countercheck facts
when considering their use in other applications. If you have any questions contact SMILE.
Author: Penny Stevens
Copy _____ of ___
Effective Date:
HEMATOLOGY SECTION
D. MANUAL TESTS
D.3. MICROHEMATOCRIT DETERMINATION
D.3.1. PRINCIPLE:
1. When anticoagulated whole blood is centrifuged, the space occupied by the packed red blood
cells is defined as the hematocrit (HCT), and is expressed as the percent of red blood cells in
a volume of whole blood. Because of its simplicity and reproducibility, the hematocrit is
one of the more accurate hematology tests.
2. A low hematocrit can be an indicator that the patient is suffering from anemia i.e., blood
loss, iron deficiency, B12 or folic acid deficiency, hemoglobin disorders and Thalassemia. A
high hematocrit can be an indicator that the patient is suffering from Polycythemia.
D.3.2. SPECIMENS:
1. Whole blood anticoagulated with EDTA or heparin is acceptable.
2. Capillary blood collected in heparinized capillary tubes may also be used.
3. If anticoagulated whole blood requires a manual HCT, a plain (non-anticoagulated) capillary
tube must be used to avoid over-anticoagulation of the specimen.
D.3.3. EQUIPMENT & REAGENTS
Equipment:
1. Plastic Clad Micro Hematocrit Tubes, Plain. Check for uniformity and gf damage before
placing into service.
2. Sealing clay
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D. Manual Tests
D.3. Microhematocrit Determination
3. Microhematocrit reader device
4. Microhematocrit centrifuge
D.3.4. CALIBRATION: Not Applicable
D.3.5. QUALITY CONTROL:
1. A control is run daily using a commercial normal whole blood control with a known value.
Document the value, and enter the value into (your laboratory system).
2. Verify that the result obtained is within range for the control used. If the result is out of
range, repeat the procedure. When the result becomes out of range for second time, notify
the Hematology supervisor immediately. Document action taken.
3. All tests are run in duplicate to eliminate errors caused by leakage.
4. The results of duplicate hematocrit determinations should agree within + 2%. If results
obtained are not within this tolerance limit, the entire procedure must be repeated. All other
results are acceptable providing the normal control is within range.
5. Everytime that the lot number is changed, control should be run 20 times before using the
new lot number of control for verification of the reference range. Annotate values.
D.3.6. PROCEDURE:
1. Mix the sample well and fill two (2) capillary tubes approximately two-thirds full.
2. Seal the dry end with sealing clay.
3. Place capillary tubes in opposite slots of microhematocrit centrifuge with the clay-filled
ends against gasket. Be sure to note position number on the (your laboratory system)
labels, if spinning specimens from more than one patient.
4. Place the head cover on centrifuge; tighten securely and close the top. Centrifuge the
capillary tubes using the predetermined maximum packing time.
5. Open the lid, remove the cover, and remove capillary tubes one at a time.
6. Using a microhematocrit reading device (Refer to figure 1, page 2, Maximum Packing Time
SOP), determine the HCT. Buffy coat should not be included in the reading, which
should be taken below the buffy coat (Grayish-red layer of leukocytes and platelets).
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D. Manual Tests
D.3. Microhematocrit Determination
7. Results should agree within + 2% for the patient's two samples.
8. Enter results into (your laboratory system).
NOTE: Visible hemolysis of the sample after centrifugation must be documented in
(your laboratory system).
D.3.7. CALCULATIONS: Not Applicable
D.3.8. INTERPRETATIONS & REPORTING RESULTS: A sticker is recorded on the
microhematocrit log with the value and initials of technician. Result value in (your
laboratory system). Refer to panic values next to normal values for critical results. The
results will be reported immediately to the requesting Physician, clinic or ward, and
documented on (your laboratory system). (Refer to the Critical Values SOP).
D.3.9. PROCEDURAL NOTES:
1. SOURCES OF ERROR:
1.1.
Excess anticoagulant decreases the HCT value because of shrinkage of erythrocytes.
1.2.
Insufficient mixing of blood before obtaining the HCT sample may decrease or
increase the HCT, depending on which part of the specimen is drawn principally into
microhematocrit tube.
1.3.
Improper sealing of capillary tube decreases the HCT because of leakage of
specimen, erythrocyte loss is greater than plasma loss.
1.4.
Inadequate centrifugation or allowing tubes to stand too long after centrifugation
increases the HCT. Results should be read within ten (10) minutes of centrifugation.
1.5.
Including the buffy coat in the reading increases the HCT.
1.6.
Improper use of the HCT reader may increase or decrease the HCT, due to parallax
(the apparent difference in position of an object, as seen separately by one eye and
then the other, or by changing the position of the head).
1.7.
Trapped plasma (the small amount of plasma that remains in the erythrocyte portion
of the spun HCT even when proper centrifugation is used) may cause the HCT to be
falsely increased.
1.8.
Certain abnormal erythrocyte shapes (e.g., spherocytes and sickle cells) inhibit
complete packing.
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D. Manual Tests
D.3. Microhematocrit Determination
1.9.
Dehydration can falsely increase HCT because of fluid loss, which causes a decrease
in plasma volume.
1.10.
When obtaining blood specimen, leaving the tourniquet on the arm too long causes
hemoconcentration, which falsely increases HCT.
1.11.
Difficult venipuncture or skin puncture may introduce interstitial fluid to the sample,
causing a falsely decreased HCT.
1.12.
Hemolysis also causes a false decrease in HCT.
2. NORMAL VALUES:
AGE
<1 day
1-3 days
2 weeks
1 month
2 months
6 months
2 years
2yrs - 6yrs
6yrs 12yrs
12yrs 18yrs
male
female
Adult
male
female
REF LOW
42
45
41
33
28
31
33
34
REF HIGH
60
67
65
55
42
41
39
40
PANIC
LOW
37
39
35
27
20
25
25
25
PANIC
HIGH
65
72
71
61
50
50
50
50
35
45
25
58
36
37
50
45
20
20
60
60
42
37
52
47
20
20
60
60
D.3.10. APPENDICES:
1. SOP Validation Form and SOP Change Control
2. SOP Approval
3. Microhematocrit Maintenance Quality Control Worksheet
D.3.11. REFERENCES:
1. Gunn, Veronica L.; Nechyba, Christian; The Harriet Lane Handbook; Mosby Book
Publisher, 2002, Pages 284 – 285.
2. Brown, Barbara A.; Hematology: Principles and Procedures, Sixth Edition; Lea and Febriger
book Publisher, 1993, pages 85-87.
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D. Manual Tests
D.3. Microhematocrit Determination
3. Lotspeich-Steininger; Clinical Hematology: Principles, Procedures, Correlation, C. V.
Mosby Book Publisher, 1992, Pages 110-112.
SOP VALIDATION
SOP NAME:
D.3. Microhematocrit Determination
Clear and specific title and principle:
Comments:
yes / no
All necessary supplies, equipment, and materials are listed:
Comments:
yes / no
SOP is sufficiently detailed to be understood but not overly complex:
Comments:
SOP text adequately describes process/procedure:
Comments:
SOP accomplishes purpose:
Comments:
yes / no
yes / no
yes / no
Reviewed by: (Name & Title)
Signature: __________________
Date: __________________
SOP CHANGE CONTROL
Date
Change
QA
Page 5 of 6
OIC
Med. Dir.
D. Manual Tests
D.3. Microhematocrit Determination
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D. Manual Tests
D.3. Microhematocrit Determination
SOP APPROVAL
SIGNATURE
DATE
PREPARER
QA COORDINATOR
LABORATORY OIC
MEDICAL DIRECTOR
ANNUAL REVIEW
REVIEWER SIGNATURE
DOCUMENT COPY CONTROL
LOCATIONS
DATE
REVIEWER SIGNATURE
DATE
DATE: ___________# COPIES __________
DATE SOP RETIRED: __________
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