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Nader Rifai

Publications and source records attributed to Nader Rifai.

130 records · Page 8Linked to original sources

Impact of the third cholesterol report from the adult treatment panel of the national cholesterol education program on the clinical laboratory.

BACKGROUND: The US National Cholesterol Education Program has recently released the third report of the Adult Treatment Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults. Incorporating new evidence and more consistent with other international intervention programs, these more complex guidelines will considerably expand indications for treatment. The implications for clinical laboratories are summarized in this report. CONTENT: LDL-cholesterol (LDL-C) remains the major focus for classification and treatment, whereas diabetes, the presence of multiple risk factors, including the metabolic syndrome, and increased triglycerides (TGs), will now require more intensive management. For screening, a fasting lipoprotein profile is recommended, adding LDL-C and TGs to the previous measurements of total cholesterol and HDL-cholesterol (HDL-C). Lowering the cutpoints defining optimal LDL-C [100 mg/dL (2.58 mmol/L)] and normal TGs [150 mg/dL (1.70 mmol/L)] and raising the cutpoint for low HDL-C to 40 mg/dL (1.03 mmol/L) will select more patients for treatment. A new marker, non-HDL-C, becomes a secondary target in treating high TGs. CONCLUSIONS: Laboratories will need to adjust reporting formats and interpretations and can expect more requests for tests to characterize secondary causes of dyslipidemia, e.g., diabetes, and for the so-called "emerging risk factors", e.g., lipoprotein(a), homocysteine, and C-reactive protein.

Adult↗

Methods for measurement of LDL-cholesterol: a critical assessment of direct measurement by homogeneous assays versus calculation.

BACKGROUND: Because LDL-cholesterol (LDL-C) is a modifiable risk for coronary heart disease, its routine measurement is recommended in the evaluation and management of hypercholesterolemia. We critically examine here the new homogeneous assays for direct determination of LDL-C. APPROACH: This review relies on published studies and data of the authors using research and routine methods for LDL-C determination. We review experience with methods from their earlier use in lipid research laboratories through the transition to routine clinical testing and the recent development of homogeneous assays. We focus on comparative evaluations and characterizations and the performance of the assays. CONTENT: Homogeneous assays seem to be able to meet current National Cholesterol Education Program (NCEP) requirements for LDL-C testing for precision (CV <4%) and accuracy (bias <4%), when samples collected from nonfasting individuals are used. In addition, all five currently available assays have been certified by the Cholesterol Reference Methods Laboratory Network. The homogeneous methods also appear to better classify individuals into NCEP cutpoints than the Friedewald calculation. However, the limited evaluations to date raise questions about their reliability and specificity, especially in samples with atypical lipoproteins. CONCLUSIONS: Available evidence supports recommending the homogeneous assays for LDL-C to supplement the Friedewald calculation in those cases where the calculation is known to be unreliable, e.g., triglycerides >4000 mg/L. Before the homogeneous assays can be confidently recommended to replace the calculation in routine practice, more evaluation is needed.

Autoanalysis↗

C-reactive protein: a nontraditional serum marker of cardiovascular risk.

Cardiovascular disease (CVD) is multifactorial in etiology. Traditional cardiovascular risk factors, such as increased cholesterol concentrations and blood pressure, are used to assess CVD risk. Recently, better understanding of the role of inflammation in atherosclerosis has prompted many to propose the measurement of various inflammatory markers to better identify those who are at increased risk. C-reactive protein (CRP) is found in endothelial atherosclerotic lesions, and evidence suggests that it may play a role in atherogenesis. Of candidate serum markers that might add information to clinical risk assessment, high-sensitivity C-reactive protein (hsCRP) measurement has the most potential for clinical use for multiple reasons: (a) high hsCRP is associated with a twofold to a threefold increase in the prevalence of myocardial infarction, stroke, and peripheral vascular disease, and it predicts incident cardiovascular events in those with and without preexisting CVD; (b) the increased risk associated with high hsCRP is independent of other established risk factors; (c) hsCRP augments the predictive capacity of the Framingham Risk Score; (d) hsCRP assays are standardized, and this analyte is biologically stable over time; (e) various risk-reducing interventions also reduce hsCRP, and research is underway to assess whether specifically targeting hsCRP reduces CVD risk. National guidelines regarding the clinical utility of hsCRP in primary and secondary prevention settings have been recently issued.

Biomarkers↗