Lipemia Interferes with Routine Clinical Biochemical Tests

The effect of lipid removal using ultracentrifugation of lipemic samples has been examined in respect to some routine biochemistry parameters, such as bilirubin, glucose, gamma-glutamyl transferase (GGT) and aspartate aminotransferase (AST).

Scientists at the University Hospital Miguel Servet (Zaragoza, Spain) selected 110 samples taken from the daily input into their laboratory. All these specimens were visibly muddy and underwent a variety of biochemical tests before and after ultracentrifugation. The process by which samples were subjected to ultracentrifugation was at 40,000 × g and +4 °C, without adjustment of density (d = 1.006 kg/L) for 18 hours in a Centrikon T-1080 Ultracentrifuge, (Kontron AG; Zurich Switzerland). Ultracentrifugation can achieve greater speed of rotation than high-speed centrifugation, and therefore generate higher centrifugal forces.

The biochemical tests determined in the first aliquot and in the aliquot subjected to ultracentrifugation were the following: cholesterol, triglycerides, alkaline phosphatase (ALP), GGT, AST, alanine aminotransferase (ALT), lactate dehydrogenase (LD), total bilirubin, total calcium, creatinine, phosphorus, glucose, iron, urea, uric acid and total protein in a Hitachi Modular D and P analyzer, (Roche Diagnostics, Mannheim, Germany).

The investigators found significant differences in all the parameters studied except for total bilirubin, glucose, GGT, and AST. The greatest differences in the parameters analyzed were found in the concentration of ALT at 7.36% and the least differences for the concentration of glucose at 0.014%. Clinically significant interferences were found for phosphorus, creatinine, total protein, and calcium. The author's concluded that a major limitation of the study is that they used ultracentrifugation to reduce lipemia and many laboratories do not have ultracentrifuges, moreover this is a very long procedure for treatment of samples that come, in many occasions, from Emergency Services. The study was published in June 2011, in Biochemia Medica.

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