Measurement of serum lipoproteins

Abstract

Although a more accurate estimate of a person's risk of cardiovascular disease can be made on the basis of the number of lipoprotein particles per unit volume in the person's blood, current methods all rely on measuring the mass of lipoprotein cholesterol per unit volume. It has been discovered that a rapid and accurate lipoprotein particle count can be obtained by photometry. A method and apparatus are provided for measuring the number of lipoprotein particles in a sample using photometry.

What is claimed: 
     
         1 . A method of measuring lipoprotein particle count in a sample from a subject, the method comprising:
 a. separating a LDL fraction, a HDL fraction and a VLDL fraction in the sample by centrifugation;   b. introducing the LDL fraction, the HDL fraction and the VLDL fraction into an apparatus for measuring the lipoprotein particle number;   c. obtaining a photometric measurement in the LDL fraction; and   d. calculating a particle count for the LDL fraction that is a function of the photometric measurement,   wherein separation of the LDL fraction, the HDL fraction and the VLDL fraction is maintained during steps (b) and (c).   
     
     
         2 . The method of  claim 1  further comprising:
 a. obtaining a photometric measurement in at least the HDL fraction; and 
 b. calculating a particle count for the HDL fraction that is a function of the photometric measurement. 
 
     
     
         3 . The method of  claim 1  further comprising:
 a. obtaining a photometric measurement in at least the VLDL fraction; and 
 b. calculating a particle count for the VLDL fraction that is a function of the photometric measurement. 
 
     
     
         4 . The method of  claim 1  further comprising:
 a. obtaining a photometric measurement in the HDL fraction; 
 b. calculating a particle count for the HDL fraction that is a function of the photometric measurement; 
 c. obtaining a photometric measurement in the VLDL fraction; and 
 d. calculating a particle count for the VLDL fraction that is a function of the photometric measurement. 
 
     
     
         5 . The method of  claim 1 , wherein the sample is contained in a sample vessel and the LDL fraction, the HDL fraction and the VLDL fraction are introduced into the apparatus in a descending order of density. 
     
     
         6 . The method of  claim 1 , wherein the sample is a blood sample or a serum sample. 
     
     
         7 . A method of measuring lipoprotein particle count in a sample from a subject, the method comprising:
 a. separating a LDL fraction, a HDL fraction, a Lp(a) fraction, an IDL fraction and a VLDL fraction in the sample by centrifugation;   b. introducing the LDL fraction, the HDL fraction, the Lp(a) fraction, the IDL fraction and the VLDL fraction into an apparatus for measuring the lipoprotein particle number;   c. obtaining a photometric measurement in at least one of the LDL fraction, the HDL fraction, the Lp(a) fraction, the IDL fraction and the VLDL fraction; and   d. calculating a particle count for each fraction for which the photometric measurement was obtained   wherein separation of the LDL fraction, the HDL fraction, the Lp(a) fraction, the IDL fraction and the VLDL fraction is maintained during steps (b) and (c).   
     
     
         8 . The method of  claim 7 , wherein the at least one fraction is the LDL fraction and at least one fraction selected from the group consisting of the HDL fraction, the Lp(a) fraction, the IDL fraction and the VLDL fraction. 
     
     
         9 . The method of  claim 7 , wherein the at least one fraction is the HDL fraction and at least one fraction selected from the group consisting of the LDL fraction, the Lp(a) fraction, the IDL fraction and the VLDL fraction. 
     
     
         10 . The method of  claim 7 , wherein the at least one fraction is the IDL fraction and at least one fraction selected from the group consisting of the HDL fraction, the Lp(a) fraction, the LDL fraction and the VLDL fraction. 
     
     
         11 . The method of  claim 7 , wherein the at least one fraction is the VLDL fraction and at least one fraction selected from the group consisting of the HDL fraction, the Lp(a) fraction, the LDL fraction and the IDL fraction. 
     
     
         12 . The method of  claim 7 , wherein the at least one fraction is the Lp(a) fraction and at least one fraction selected from the group consisting of the HDL fraction, the IDL fraction, the LDL fraction and the VLDL fraction. 
     
     
         13 . The method of  claim 7 , wherein the at least one fraction is the HDL fraction, the Lp(a) fraction, the LDL fraction, the IDL fraction and the VLDL fraction. 
     
     
         14 . The method of  claim 7 , wherein the sample is contained in a sample vessel and the HDL fraction, the Lp(a) fraction, the LDL fraction, the IDL fraction and the VLDL fraction are introduced into the apparatus in a descending order of density. 
     
     
         15 . The method of  claim 7 , wherein the sample is a blood sample or a serum sample.