Comparison of low-density lipoprotein size by polyacrylamide tube gel electrophoresis and polyacrylamide gradient gel electrophoresis

We evaluated a low-density lipoprotein (LDL) subfraction separation method using polyacrylamide tube gel electrophoresis (PTGE) and compared it with the reference method, polyacrylamide gradient gel electrophoresis (PGGE-REF). Excellent intra-assay and interassay coefficients of variation were obtained (<4%)for PTGE. For 102 subjects, LDL subclasses correlated most significantly with triglyceride (TG) level, high-density lipoprotein (HDL) cholesterol level, total cholesterol/HDL cholesterol ratio, and non-HDL cholesterol level (P < .05). The distribution of large LDL (76%) was predominant for subjects with low TG levels (<150 mg/dL [1.69 nmol/L]), while distribution of small LDL (79%) was predominant,for subjects with high TG levels (>200 mg/dL [2.26 mmol/L]). Excellent agreement between the methods was observed (weighted kappa = 0.78). Of 51 samples classified as small, dense LDL by PGGE-REF, none were misclassified as large LDL and 4 as intermediate LDL by PTGE (92% concordance); of 44 samples classified as large LDL by PGGE-REF, 3 were misclassified as small and 7 as intermediate by PTGE (77% concordance). The PTGE method is precise and compares favorably with PGGE-REF. It has the advantage of being simple, less expensive, and more suitable for use in the clinical laboratory.