How high triglycerides affect dog blood tests and clearing methods

Abstract

Triglyceride concentrations in dogs with hyperlipidemic disorders can exceed concentrations used by assay manufacturers for interference testing. High-speed centrifugation or the polar solvent LipoClear reduce triglyceride concentrations, but efficacy requires evaluation in veterinary species. We determined the effect of marked hypertriglyceridemia on canine biochemistry testing; assessed the ability of high-speed centrifugation or LipoClear to correct lipemic interferences; and determined if LipoClear introduces inaccuracy into biochemistry assays. Fifteen pooled canine serum samples were aliquoted and spiked with equal volumes of water or Intralipid [triglyceride concentration 33.9 mmol/L (3,000 mg/dL)]. Intralipid aliquots underwent lipid removal by high-speed centrifugation or LipoClear treatment, and a water-spiked aliquot underwent LipoClear treatment. Biochemistry panels were performed using a Vitros 4600 chemistry analyzer. Results were compared by paired-test or Wilcoxon test. Total observed errors were considered clinically acceptable if below veterinary allowable total error (TEa) guidelines. Statistically significant (≤ 0.05) interferences were introduced by Intralipid for 15 of 15 analytes. Median observed error exceeded TEa for potassium and enzymatic carbon dioxide, neither of which were identified by the manufacturer as susceptible to lipemic interference. After centrifugation, median observed error exceeded TEa for potassium and chloride. LipoClear treatment resulted in median errors that exceeded TEa for total protein, chloride, and phosphorus. Given that severe lipemia can occur in dogs with primary or secondary hyperlipidemia, veterinary laboratories should perform their own interference testing at triglyceride concentrations relevant to their patient population and provide this information to clinicians to ensure optimal case management.