Reference values assessment in a Mediterranean population for small dense low-density lipoprotein concentration isolated by an optimized precipitation method
Received 16 January 2017
Accepted for publication 4 April 2017
Published 6 June 2017 Volume 2017:13 Pages 201—207
Checked for plagiarism Yes
Review by Single-blind
Peer reviewers approved by Dr Colin Mak
Peer reviewer comments 2
Editor who approved publication: Dr Konstantinos Tziomalos
Bárbara Fernández-Cidón,1–3 Ariadna Padró-Miquel,1 Pedro Alía-Ramos,1 María José Castro-Castro,1 Marta Fanlo-Maresma,4 Dolors Dot-Bach,1 José Valero-Politi,1 Xavier Pintó-Sala,4 Beatriz Candás-Estébanez1
1Clinical Laboratory, Hospital Universitari de Bellvitge, L’Hospitalet de Llobregat, Spain; 2Department of Biochemistry, Molecular Biology and Biomedicine, Autonomous University of Barcelona (UAB), Barcelona, Spain; 3Department of Pharmacotherapy, Pharmacogenetics and Pharmaceutical Technology, Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), L’Hospitalet de Llobregat, Spain; 4Cardiovascular Risk Unit, Hospital Universitari de Bellvitge, L’Hospitalet de Llobregat, Spain
Background: High serum concentrations of small dense low-density lipoprotein cholesterol (sd-LDL-c) particles are associated with risk of cardiovascular disease (CVD). Their clinical application has been hindered as a consequence of the laborious current method used for their quantification.
Objective: Optimize a simple and fast precipitation method to isolate sd-LDL particles and establish a reference interval in a Mediterranean population.
Materials and methods: Forty-five serum samples were collected, and sd-LDL particles were isolated using a modified heparin-Mg2+ precipitation method. sd-LDL-c concentration was calculated by subtracting high-density lipoprotein cholesterol (HDL-c) from the total cholesterol measured in the supernatant. This method was compared with the reference method (ultracentrifugation). Reference values were estimated according to the Clinical and Laboratory Standards Institute and The International Federation of Clinical Chemistry and Laboratory Medicine recommendations. sd-LDL-c concentration was measured in serums from 79 subjects with no lipid metabolism abnormalities.
Results: The Passing–Bablok regression equation is y = 1.52 (0.72 to 1.73) + 0.07x (−0.1 to 0.13), demonstrating no significant statistical differences between the modified precipitation method and the ultracentrifugation reference method. Similarly, no differences were detected when considering only sd-LDL-c from dyslipidemic patients, since the modifications added to the precipitation method facilitated the proper sedimentation of triglycerides and other lipoproteins. The reference interval for sd-LDL-c concentration estimated in a Mediterranean population was 0.04–0.47 mmol/L.
Conclusion: An optimization of the heparin-Mg2+ precipitation method for sd-LDL particle isolation was performed, and reference intervals were established in a Spanish Mediterranean population. Measured values were equivalent to those obtained with the reference method, assuring its clinical application when tested in both normolipidemic and dyslipidemic subjects.
Keywords: sd-LDL-c, small dense lipoprotein, sd-LDL reference values
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