DEVELOPMENT OF APPROXIMATE FORMULA FOR LDL-CHOL, LDL-APO-B AND LDL-CHOL LDL-APO-B AS INDEXES OF HYPERAPOBETALIPOPROTEINEMIA AND SMALL DENSELDL/

Estimation of LDL-chol and LDL-apo B is useful for the diagnosis of hy perapobetalipoproteinemia (normal LDL-chol with increased LDL-apo B), which is one of the most commonly occurring lipoprotein disorders asso ciated with atherosclerotic cardiovascular diseases. The LDL-chol/LDL- apo B ratio reflects the level of small dense LDL, which is an importa nt risk factor for IHD, CVD and ASO. In order to estimate LDL-apo B an d LDL-chol/LDL-apo B ratio from blood chol, TG, HDL-chol and apo B val ues, we developed a formula for LDL-chol {0.94Chol-0.94HDL-chol-0.19TG }, LDL-apo B {apo B-0.09Chol+0.09HDL-chol-0.08TG}, and LDL-chol/LDL-ap o B [{0.94Chol-0.94HDL-chol-0.19TG}/{apo B-0.09Chol + 0.09HDL-chol-0.0 8TG}], using ultracentrifugal data from 2179 subjects. These were calc ulated by the least squares method on the assumption that a certain co mpositional relationship exists between Chol, TG and apo B in VLDL, ID L and LDL. Friedewald's formula for LDL-chol (Chol-HDL-chol-0.2TG) inc ludes IDL-chol, but the present new formula theoretically excludes IDL -chol. It suggests a better estimation for the correct LDL-chol. Estim ated LDL-apo B is useful for the diagnosis of hyperapobetalipoproteine mia and detection of small dense LDL. Without performing ultracentrifu ge, additional information is obtained for the quantitative and qualit ative alteration of LDL, such as small dense LDL. The above formulae a nd a new classification of lipoproteinemia including apo B were applie d to the analyses of lipoprotein profiles of subjects with cardiovascu lar diseases, which were compared with those in the general population . Hyperapobetalipoproteinemia with high TG was observed 2-3 times more frequently in subjects with CAD, MI and ASO than in the Suita populat ion. Lower ratios of LDL-chol/LDL-apo B, reflecting preponderance of s mall dense LDL, were observed in the above three groups. Type IIb and combined low HDL-chol were also frequent phenotypes in CAD, A-Th and A SO. The present formulae are useful for the detailed analyses of lipop rotein disorders in both qualitative as well as quantitative aspects. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.