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Chemistry Specimen Retention

There are arguments in the literature both for and against the use of fasting samples for lipid levels. Some groups suggest non-fasting specimens may actually be better at predicting cardiac risk and making therapeutic decisions, while others have provided reasons why fasting levels are still needed. Still, the majority of clinical guidelines and intervention trials for lipids, completed with non- and diabetic populations, are based on fasting samples. Trials of statin therapies have used fasting lipids for the most part but two major studies (MRC/BHF and SEARCH) have published outcomes using non-fasting specimens

The 2012 Canadian Cardiovascular Society (CCS) Guidelines for the Diagnosis and Treatment of Patients with Dyslipidemia classify patients and treatment goals based on risk category and lipid measurements. Treatment approach and optimal ranges are defined for each cardiovascular disease (CVD) category based on LDL-Cholesterol (LDL-C), non-HDL-Cholesterol (non HDL-C; i.e. TC less HDL-C) and apolipoprotein B (Apo B) concentrations. LDL-C is calculated by the Friedewald equation, which includes measured triglycerides, total cholesterol (TC) and HDL-C. Food intake influences measured triglycerides and therefore calculated LDL-C. Note that the TC/HDL-C is no longer included in the guidelines as a treatment target although it is still recognized as a significant risk indicator if >6.0.1

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