Investigation of unusual high serum indices for lipemia in clear serum samples on Siemens analysers Dimension

INTRODUCTION We present our work of monitoring 202 different patients with markedly elevated serum index for lipemia whereby serum samples were clear. We tried to clarify the cause of occurrence of these indices which were detected in the years 2006-2010 on Siemens Dimension analyzers. MATERIALS AND METHODS In samples with unusual lipemia index we measured the concentration of lipids (total cholesterol, triglycerides, HDL and LDL cholesterol, Lp(a), ApoA1, ApoB), total proteins and checked for possible interferents (rheumatoid factor, immunoglobulins). We performed serum protein and immuno- electrophoresis. We investigated the repeatability of unusual lipemia indices during the day and after different time periods and we compared them on four different analyzers (RXL Max, Vista, Hitachi 911 and former Olympus AU640). RESULTS In 87% of 202 samples we found a monoclonal or biclonal peak in serum protein electrophoresis. Different types of paraproteins were confirmed with immunofixation electrophoresis. In the remaining 13%, polyclonal elevated concentrations of immunoglobulins were measured. Other parameters had no influence on appearing of these indices. The repeatability of indices was good during the first day of measurements (P values > 0.05) and markedly lower in the next days or after 3 and 12 months (P values <0.05). The indices were elevated only on Dimension analyzers, but not on Hitachi and former Olympus analysers. CONCLUSION A markedly elevated lipemia index in a clear serum sample measured on Siemens analyzers Dimension indicates a high possibility for the presence of a paraprotein in the sample.