A colleague on the East Coast of the USA wants to know what methods others use for determining if samples are too lipemic to test for viral disease markers in blood donors. There are defined sample suitability requirements in most test kit package inserts specifying an upper limit (e.g., 800 mg/dL); however, most of the simple and unsophisticated techniques to determine lipemia levels in donor samples cannot distinguish levels above 250 mg/dL with any degree of accuracy and therefore one could discard samples for testing simply because the level of lipemia cannot be clearly determined. One such method that is commonly used is to employ a sample suitability chart, but in her opinion, such a chart is fairly limited in its application. For example, her laboratory uses a Sample Integrity Chart produced by Vitros and provided to them by Ortho. In her opinion, this chart is clearly far from ideal, but at present it is the best method available that she is aware of. (Her analogy is like using a pH dipstick to determine the presence/absence of bacteria in a platelet unit).

Editor's note: Colleagues might find the related e-Network Forum discussion interesting - Acceptability of lipemic apheresis platelets for transfusion.

The following response has been received.

ADDENDA Jan. 2, 2005

1. A colleague in Southern California reports that at his busy laboratory grossly lipemic serum or plasma samples are not used in many of their clinical laboratory tests due to interference. To determine lipemia they use the same microhematocrit method that they use to determine hemolysis by employing the following guideline:

• Gross lipemia: newspaper print or black text print cannot be read through the plasma. Plasma appears milky.
• Moderate lipemia: newspaper print or black text print can be read through the plasma but with difficulty. Plasma appears almost milky.
• Slight lipemia: newspaper print or black text print can be read through the plasma easily. Plasma appears slightly cloudy.

Attached is an example (pdf file) of what the microhematocrit tubes look like when samples are grossly jaundiced, grossly lipemic and grossly hemolyzed.

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Ira A. Shulman, MD
CBBS e-Network Forum Editor & Moderator