There are different types of LDL particles. They are classified by at least two phenotypes (A and B).
Phenotype B is associated with heart disease (LDL subclass phenotypes and triglyceride metabolism in non-insulin-dependent diabetes. K R Feingold, C Grunfeld, M Pang, W Doerrler and R M Krauss. Arteriosclerosis, Thrombosis, and Vascular Biology. 1992;12:1496-1502, originally published December 1, 1992).
A common, heritable phenotype characterized by the predominance of small, dense LDL particles (LDL subclass phenotype B) is associated with relatively increased concentrations of plasma triglycerides, reduced levels of high density lipoprotein, and increased risk of coronary artery disease in comparison with subjects with larger LDL (LDL subclass phenotype A).
The LDL B phenotype was associated with higher plasma triglyceride levels and a trend toward lower high density lipoprotein cholesterol levels compared with the LDL A phenotype in the NIDDM subjects, as has been previously observed in control groups.
Indices of diabetic control, such as fasting and hemoglobin A1 levels, were similar regardless of LDL phenotype pattern, suggesting that glycemic control was not likely to account for the increase in the LDL B phenotype. In both control and NIDDM subjects, the clearance of triglyceride-rich lipoproteins was slowed in the subjects with the LDL phenotype B compared with those with the A phenotype.
The mix of Phenotype A and Phenotype B LDL particles can be determined from other blood numbers (The American Journal of Cardiology Volume 94, Issue 2, 15 July 2004, Pages 219-222. Accuracy of the triglyceride to high-density lipoprotein cholesterol ratio for prediction of the low-density lipoprotein phenotype B. Viktor Hanak MD, Julian Munoz MD MSPH, Joe Teague MD, Alfred Stanley Jr. MD. Vera Bittner MD MSPHc):
A triglyceride/HDL cholesterol ratio of 3.8 divided the distribution of LDL phenotypes with 79% (95% confidence interval [CI] 74 to 83) of phenotype B greater than and 81% (95% CI 77 to 85) of phenotype A less than the ratio of 3.8. The ratio was reliable for identifying LDL phenotype B in men and women.
I created an on-line lipids calculator to calculate the number from blood test results.