Clinical Chemistry and Laboratory Medicine (CCLM)
Published in Association with the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM)
Editor-in-Chief: Plebani, Mario
Ed. by Gillery, Philippe / Lackner, Karl J. / Lippi, Giuseppe / Melichar, Bohuslav / Schlattmann, Peter / Tate, Jillian R.
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Application of a modified precipitation method for the measurement of small dense LDL-cholesterol (sd-LDL-C) in a population in southern Brazil
1Post-Graduation Program in Pharmacy, Department of Clinical Analyses, Health Sciences Center, Federal University of Santa Catarina, Florianópolis, SC, Brazil
Citation Information: Clinical Chemistry and Laboratory Medicine (CCLM). Volume 50, Issue 9, Pages 1649–1656, ISSN (Online) 1437-4331, ISSN (Print) 1434-6621, DOI: 10.1515/cclm-2011-0797, March 2012
- Published Online:
Background: In the study reported herein, we used the precipitation method employing heparin-Mg2+, with slight modifications to avoid lipemia interference, to measure small dense-low density lipoprotein-cholesterol (sd-LDL-C) in Brazilian subjects with a high risk of developing cardiovascular diseases.
Methods: Lipemic samples were diluted with various solvents prior to precipitation with heparin-Mg2+. Validation assays were performed with ultracentrifugation (n=100) and the reproducibility of sd-LDL-C measured in diluted serum (n=50). The applicability of this modification was evaluated by measuring sd-LDL-C in 434 southern Brazilian normolipidemic, dyslipidemic and type 2 diabetes mellitus (T2DM) individuals.
Results: Lipemic serum diluted with 100 mmol/L phosphate buffer pH 8.5 was effective for the quantification of sd-LDL-C, which was correlated with non-diluted serum (r=0.961; p<0.0001) and with ultracentrifugation (r=0.705; p<0.0001). Ultracentrifugation sd-LDL-C was 0.08 mmol/L (CI 95%: –0.42–0.58 mmol/L) higher than the precipitation method (p>0.05). Subjects with dyslipidemias and T2DM had, respectively, 2.3 and 2.6-fold higher sd-LDL-C concentrations than normolipidemic individuals (p<0.05). The incidence of normolipidemic subjects with a high concentration of sd-LDL-C was only 2.2%. The sd-LDL-C was found to be enhanced by 8.3% every 10 years and young normolipidemic men had 24% higher sd-LDL-C than young women (p<0.05). Lipid-lowering therapy reduced sd-LDL-C by 26% (p<0.001).
Conclusions: In this paper we described a simple and inexpensive approach to improving the measurement of sd-LDL-C in high-triglycerides serum. Furthermore, we showed that southern Brazil dyslipidemic and T2DM individuals have increased sd-LDL-C concentrations.