(HealthDay News) — At lower values of measured LDL cholesterol, the variation and bias of calculated LDL cholesterol increases, according to a study published in The American Journal of Cardiology.
Noting that the Friedewald equation for calculation of LDL cholesterol is the primary laboratory method for routine LDL cholesterol measurement, Jeffrey W. Meeusen, PhD, from the Mayo Clinic in Rochester, Minnesota, and colleagues compared the accuracy and reproducibility of calculated LDL cholesterol <130 mg/dL to LDL cholesterol measured by beta quantification (considered the gold standard).
The comparison was conducted in 15,917 patients with fasting triglyceride concentrations <400 mg/dL.
At lower values of measured LDL cholesterol, variation and bias of calculated LDL cholesterol increased, according to the study results. For a calculated LDL cholesterol of 70 mg/dL and 30 mg/dL, the 95% CIs were 60 mg/dL to 86 mg/dL and 24 to 60 mg/dL, respectively.
“Calculated LDL cholesterol <30 mg/dL (0.8 mmol/L) should not be reported because of significant deviation from the gold standard measured LDL cholesterol results, and caution is advised when using calculated LDL cholesterolF values <70 mg/dL (1.8 mmol/L) to make treatment decisions,” the researchers wrote.