Month-to-month variability of lipids, lipoproteins, and apolipoproteins and the impact of acute infection in adolescents

Objective: To assess month-to-month variability of total cholesterol, triglycerides, high-density lipoprotein-cholestero (HDL-C), calculated low-density lipoprotein-cholesterol (LDL-C), apolipoprotein Al, apolipoprotein B, and lipoprotein (a), as well as factors that could influence variability including recent acute infection in an adolescent population. Methods: Sixty-three high school students had fasting lipids and lipoproteins measured at 4 separate times during the school year and another venipuncture 3 to 7 days after recovery from an acute infection. Erythrocyte sedimentation rate was also measured. Coefficients of variation were calculated for each study variable. The influence of recent infection on variability was assessed. Results: The 50th and 95th percentiles, respectively, for the coefficient of variation for each variable were as follows: total cholesterol, 7.3% and 13.6%; triglycerides, 22% and 47.3%; HDL-C, 7.9% and 16.8%; LDL-C, 12.1% and 25%; apolipoprotein Al, 6.3% and 15.2%; apolipoprotein B, 9.5% and 17.2%; and lipoprotein (a), 19.3% and 40%. Recent infection significantly lowered HDL-C (4 mg/dL; P < .0001) and apolipoprotein Al (7 mg/dL; P < .005). Conclusions: Clinicians evaluating lipids and lipoproteins serially should expect significant visit-to-visit variation in triglycerides and calculated LDL-C values. Assessment of HDLC and apolipoprotein Al should not be done within 2 weeks of an acute infection. Apolipoproteins B and Al have slightly less variability than their respective lipoprotein cholesterol values (LDL-C and HDLC).