The effect of VLDL particles on the accuracy of a direct LDL-cholesterol method in type 2 diabetic patients.
OBJECTIVE
To assess the accuracy of the direct method LDL-c Plus, in type 2 diabetic patients.LDL-c Plus was measured in 64 consecutive samples of type 2 diabetic patients and compared with betaquantification (BQ), Friedewald's and an alternative formula.


METHODS
LDL-c Plus was also measured in the VLDL (d<1.006 Kg/L) fraction of these samples and in total serum and the VLDL fraction of a phenotype III patient, before and after diluting it with saline or VLDL from normolipidemic subjects.


RESULTS
LDL-c Plus showed a significant, constant bias (-8.5 +/- 5.6%) against BQ which correlated with VLDL-cholesterol/total triglyceride ratio (r = 0.760, p < 0.0005); bias decreased to zero when the ratio increased. In the VLDL fraction of the diabetic patients and the phenotype III patient LDL-c Plus measured 20.7 +/- 11.6% and 56.2% of the cholesterol, respectively. Dilution with saline did not alter the latter percentage, whereas dilution with normolipidemic VLDL reduced it showing that LDL-c Plus recognized cholesterol-enriched particles in the d<1.006 Kg/L. Friedewald's formula also showed a significant, constant bias (-3.1 +/- 6.4%) against BQ, whereas the alternative formula did not (0.5 +/- 6.1%). Both calculations classified patients better than LDL-c Plus did at NCEP cut-off points.


CONCLUSIONS
In type 2 diabetic patients, LDL-c Plus underestimates LDL-c but measures cholesterol associated to IDL particles in the d<1.006 Kg/L fraction. Although LDLc-Plus might be a better cardiovascular risk estimator when well standardized, at the moment, it does not seem to be superior to calculations.
Department of Endocrinology, Hospital de Sant Pau, Barcelona, Spain.
Ana María
AM
Wägner
Edgar
E
Zapico
Rosa
R
Bonet
Antonio
A
Pérez
Jordi
J
Ordóñez-Llanos
D002318:Cardiovascular Diseases / Q000209:etiology; D008078:Cholesterol, LDL / Q000097:blood*; D003924:Diabetes Mellitus, Type 2 / Q000097:blood*; D005260:Female; D006801:Humans; D006952:Hyperlipoproteinemia Type III / Q000097:blood; D007201:Indicator Dilution Techniques; D017270:Lipoprotein(a) / Q000097:blood; D008074:Lipoproteins / Q000097:blood; D053419:Lipoproteins, IDL; D008079:Lipoproteins, VLDL / Q000097:blood*; D008297:Male; D012680:Sensitivity and Specificity; D014280:Triglycerides / Q000097:blood
D008078:Cholesterol, LDL; D017270:Lipoprotein(a); D008074:Lipoproteins; D053419:Lipoproteins, IDL; D008079:Lipoproteins, VLDL; D014280:Triglycerides