The effect of fasting status on the determination of low-density and high-density lipoprotein cholesterol

To determine the effect of a self-selected meal on concentrations of low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) in a screening setting and to determine the effect of using nonfasting values to classify individuals according to National Cholesterol Education Program guidelines.

Study subjects were 115 employees who had previously participated in worksite total cholesterol screening, selected by stratified random sampling for sex and total cholesterol levels. Total cholesterol, triglycerides, HDL-C, and estimated LDL-C were determined before subjects ate a self-selected breakfast and 3 and 5 hours after eating it.

LDL-C values determined 3 and 5 hours following breakfast were approximately 7% and 2.5% lower, respectively, than fasting values. Use of 3-hour and 5-hour LDL-C determinations to classify individuals with elevated fasting levels (> or = 3.36 mmol/L) resulted in false-negative rates of 20% and 14%, respectively. Three- and 5-hour HDL-C values were approximately 4% and 1.5% lower, respectively, than fasting levels. Use of 3-hour HDL-C values to classify individuals with low fasting levels (< 0.91 mmol/L) resulted in no false-negatives, whereas 1 of 7 individuals with low fasting HDL-C was misclassified when 5-hour values were used.

These results support the 1993 National Cholesterol Education Program guidelines that LDL-C levels should be determined only in fasting persons, and that nonfasting HDL-C values may be acceptable for screening purposes.