Procedures for Certification of CRMLN Manufacturers

A manufacturer seeking certification by CDC must collaborate with a CRMLN member laboratory on a method comparison study. The manufacturer is responsible for providing the sera used in the study, and provides the reference measurements for the samples. CDC’s Lipids Reference Laboratory evaluates the measurement results generated by the CRMLN member laboratory and the manufacturer, and issues a certificate to the manufacturer if it meets required analytical performance criteria.

Separate protocols for obtaining new certificates and a simplified protocol for obtaining recertification are used for total cholesterol measurements. Recertification protocols for HDL-C and LDL-C are currently not available. Certificates for manufacturers expire two years after the date they are issued.

Whether or not measurement results obtained from commercial tests are in line with those from CRMLN reference methods is assessed, using established protocols such as the Clinical and Laboratory Standards Institute (CLSI) Protocol EP9-A, “Method Comparison and Bias Estimation Using Patient Samples.” This protocol requires analyzing a minimum of 40 patient specimens by both the test method and reference method. The mean bias among all patient samples between the test method and the reference method is calculated and the imprecision is determined. The mean bias is an estimation of the calibration bias. Current performance criteria are:

Analytical Performance Criteria for Tests Used
to Assess Cardiovascular Disease (CVD) Risk

Analytical Performance Criteria for Tests Used to Assess Cardiovascular Disease (CVD) Risk
Analyte Maximum Allowable
Mean Bias1
Maximum Allowable Imprecision Total Error
TC ±3.0% CV ≤3.0%
HDL-C ±5.0% CV ≤4.0%
LDL-C ±4.0% CV ≤4.0%
TG ±5.0% CV ≤5.0% ±13.3% per measurement

1bias to the reference method performed by one of the CRMLN member laboratories

CV: Coefficient of variation
TC: Total Cholesterol
HDL-C: High Density Lipoprotein Cholesterol
LDL-C: Low Density Lipoprotein Cholesterol
TG: Total Glycerides

Separate certificates are issued for comparison studies using spectrophotometric and mass spectrometric reference methods.

Manufacturers Certification Protocols


Use of trade names is for identification only and does not constitute endorsement by the CDC or the U.S. Department of Health and Human Services.