What is the maximum coefficient of variation allowed for LDL-C measurements under NCEP guidelines?

What is the maximum coefficient of variation allowed for LDL-C measurements under NCEP guidelines?

• A. 2%
• B. 4%
• C. 6%
• D. 8%

Answer: (B)

Precision of LDL-C testing is described by the coefficient of variation, which shows how much repeated measurements of the same sample can differ as a percentage of the mean. NCEP guidelines set this imprecision limit for LDL-C at four percent, aiming for reliable and comparable results across laboratories. In practical terms, a measurement of 100 mg/dL should have a spread (standard deviation) around 4 mg/dL or less to stay within that limit. This level matters because LDL-C informs risk assessment and treatment decisions, and small differences near clinical cutoffs can change management. Values tighter than four percent would be very challenging for routine labs, while looser limits could lead to clinically meaningful misclassification.

Precision of LDL-C testing is described by the coefficient of variation, which shows how much repeated measurements of the same sample can differ as a percentage of the mean. NCEP guidelines set this imprecision limit for LDL-C at four percent, aiming for reliable and comparable results across laboratories. In practical terms, a measurement of 100 mg/dL should have a spread (standard deviation) around 4 mg/dL or less to stay within that limit. This level matters because LDL-C informs risk assessment and treatment decisions, and small differences near clinical cutoffs can change management. Values tighter than four percent would be very challenging for routine labs, while looser limits could lead to clinically meaningful misclassification.