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|Test code||HCT, HCTM, CBC, CBCD, ORHT, LBGH|
|Performed by||Parnassus, Mission Bay & Mt. Zion Hematology|
|In House Availability||Test available 24 hours per day 7 days per week|
|Method||Calculation from MCV and RBC Count or measured by Conductance (iStat)|
|Container type||Lavender top|
|Amount to Collect||1 mL blood|
|Sample type||EDTA whole blood|
|Preferred volume||1 mL blood|
|Min. Volume||250 uL (microtainer sample) See notes.|
|Synonyms||Hct; Crit; PCV; Packed cell volume|
|Turn around times||STAT 1 hour, Routine 4 hours|
|Additional information||Also part of CBC & CBC w/differential
Reference ranges are also dependent upon the intensity of chronic exposure to high altitudes or to tobacco smoke, as well as to the duration of pregnancy. A manual assay will be performed whenever accurate results cannot be obtained on an automated instrument because of some intrinsic abnormality of the specimen, such as the presence of cold agglutinins.
For technical reasons related to plasma trapping between the centrifuged RBCS, manual results are usually 1-2% higher than results by automated methods.
Conductance (e.g. iStat) method may yield spurious results in patients with high volume crystalloid infusion (particularly patients on bypass pump) or other plasma protein derangements. Conductance values may not compare well with calculated Hct results.
Capillary tubes for spun hematocrits require only 100 µL vs 250 µL for a microtainer, but they are leak-prone, fragile, hazardous to handle, less informative than a CBC and-because they are imprecise-should be run in duplicate, diminishing any benefit of requiring less blood volume. We discourage their use but will accept them for processing. Two capillaries should be submitted in a labeled tube to minimize breakage during transport, and should be accompanied by a requisition on which "SPUN HCT" is written next to the box checked for a CBC
|Last Updated||1/27/2015 2:28:33 PM|