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Direct measurement of LDL-C in children: performance of two surfactant-based methods in a general pediatric
H H Yu1, R Markowitz, S D De Ferranti
1From the Department of Pathology and Laboratory Medicine, Children's Hospital, Harvard Medical School, Boston, MA 02115, USA.
Insights
Direct low-density lipoprotein cholesterol (LDL-C) assays show limited utility for screening children. While nonfasting LDL-C measurements are convenient, these direct assays had lower sensitivity and accuracy compared to traditional methods.
Area of Science:
- Pediatric lipidology
- Clinical chemistry
- Diagnostic assay development
Background:
- Pediatric advisory groups recommend selective screening for dyslipidemia in children.
- Current clinical measurement of low-density lipoprotein cholesterol (LDL-C) relies on the Friedewald calculation using fasting samples.
- Nonfasting LDL-C measurement would offer significant clinical convenience for pediatric lipid screening.
Purpose of the Study:
- To evaluate the performance of two surfactant-based direct LDL-C assays.
- To compare the accuracy of direct LDL-C assays in both fasting and nonfasting pediatric samples.
- To assess the clinical utility of direct LDL-C assays for pediatric dyslipidemia screening.
Main Methods:
- Paired fasting and nonfasting blood samples were collected from 100 children.
- Two direct LDL-C assays (N-geneous and Roche) were tested.
- Assay performance was compared against ultracentrifugation-dextran-sulfate-Mg(2+) precipitation (UC-DS) as a reference method and the Friedewald calculation.
Main Results:
- Direct LDL-C assays showed lower LDL-C values compared to Friedewald and UC-DS in fasting samples.
- Nonfasting samples exhibited increased negative bias with direct LDL-C assays.
- Correlation with UC-DS was highest for Friedewald and fasting N-geneous, and lowest for nonfasting Roche assay.
- Sensitivity for detecting elevated LDL-C was lower with direct assays compared to Friedewald.
Conclusions:
- The evaluated direct LDL-C assays demonstrated limited utility for screening children for dyslipidemia.
- These assays may possess utility in the ongoing management of pediatric lipid disorders.
- Further research is needed to refine direct LDL-C measurement methods for pediatric populations.
Objectives:
Several pediatric advisory groups have recommended selective screening for dyslipidemia in children. Low-density lipoprotein cholesterol (LDL-C) is measured clinically with the Friedewald calculation in fasting samples. Nonfasting measurement of LDL-C would be clinically useful in children.
Design And Methods:
In the present study, we examine the performance of two surfactant-based direct LDL-C assays in paired samples, fasting and nonfasting, from 100 children.
Results:
LDL-C in the fasting state was significantly lower with the Friedewald estimation: 2.43 +/- 0. 61 mmol/L, N-geneous (Genzyme Corp.) direct LDL-C: 2.30 +/- 0.59 mmol/L, and Roche (Roche Diagnostics) direct LDL-C: 2.32 +/- 0.57 mmol/L than with ultracentrifugation-dextran-sulfate-Mg(2+) precipitation (UC-DS): 2.47 +/- 0.64 mmol/L. Moreover, there was increased negative bias using nonfasting samples with N-geneous: 2. 25 +/- 0.56 mmol/L and Roche: 2.26 +/- 0.56 mmol/L compared with fasting UC-DS. Correlation with US-DS was highest for Friedewald (r = 0.974) and fasting N-geneous (r = 0.973), and lowest with nonfasting N-geneous (r = 0.849) and Roche in fasting (r = 0.891) and nonfasting samples (r = 0.747). The sensitivity at LDL-C concentration of 2.85 mmol/L for the two direct methods when either fasting or nonfasting samples were used, was lower than that obtained with Friedewald.
Conclusion:
Overall, these direct LDL-C assays demonstrated limited utility in screening children but may be useful in the management of lipid disorders.