VARIABILITY OF LIPID MEASUREMENTS - RELEVANCE FOR THE CLINICIAN

Decreasing the large test variability associated with measurements of blood cholesterol, triglyceride, and high-density lipoprotein (HDL)- a nd low-density lipoprotein (LDL)-cholesterol is likely to improve the classification of coronary heart disease (CHD) risk and allow improved monitoring of lipid-lowering treatments. However, improving test prec ision will benefit the clinician only if (a) the analytical test varia bility is high relative to the biological test variability and (b) det ecting subtle responses to diet or drug therapy is clinically importan t. Improving HDL- and LDL-cholesterol test precision can be expected t o increase the clinical usefulness of these measurements because value s for HDL- and LDL-cholesterol correlate closely with CHD risk; are as sociated with small, yet clinically important, changes in response to diet and (or) drug therapy; and have substantial analytical test varia bility relative to biological variability. On the other hand, measurem ents of both blood cholesterol and triglyceride have high biological r elative to analytical variability, and do not correlate as closely wit h CHD risk. Therefore, further improvements in precision for these mea surements are less likely to be useful to the clinician.