14 SPECIMEN COLLECTION AND HANDLING
Cholestech LDX System Procedure Manual
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Recommended Optional Information
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2.8 Proper Specimen Storage
1. Anticoagulated blood may be sampled directly from the tube after mixing. This
step should be performed within 30 minutes of collection. Use a MiniPet
™
Pipette
and tips or a micropipetter calibrated to deliver 35 to 50 µL. Do not use the Cholestech
capillary tubes for transferring venous whole blood, serum or plasma to
a Cholestech LDX test cassette.
2. Glucose levels decrease due to glycolysis at the rate of 5 to 10 mg/dL per hour in whole
blood at room temperature.
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3. Serum samples should be allowed to clot for 30 minutes and then centrifuged. Serum
should be separated from the blood cells and stored refrigerated in a tightly sealed
sample tube at 36– 46°F (2 – 8°C) until a test is performed.
4. When plasma samples are used, plasma should be separated from the blood cells
within 30 minutes of collection and stored refrigerated in a tightly sealed sample tube
at 36– 46°F (2– 8°C) until the test is performed.
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5. If using serum or plasma samples to evaluate or validate the Cholestech LDX System,
the following information should be considered: Cholesterol levels are stable in serum
or plasma for 4 days at 36– 46°F (2– 8°C) or for 3 months at –4°F (–20°C). HDL
cholesterol levels are stable in serum or plasma samples for up to 24 hours when
stored at 36– 46°F (2– 8°C) or up to 2 weeks when stored at –4°F (–20°C).
Triglyceride levels are stable in serum or plasma samples for 7 days when stored at
36– 46°F (2– 8°C) or for 3 months when stored at –4°F (–20°C).
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Glucose is stable in
serum samples for up to 8 hours at 77ºF (25°C), or up to 72 hours at 36 –46°F
(2–8°C) when the serum separated from the blood cells is unhemolyzed and kept free
of bacterial contamination.
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Minimal loss of ALT activity occurs when serum samples
are stored up to 2 days at 36–46ºF (2– 8°C). Serum samples should be stored frozen if
they are to be kept more than 3– 4 days.
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6. Serum and plasma samples should be brought to room temperature before the test is
performed.
7. Mix all samples thoroughly by gentle inversion 7–8 times before testing.
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