M.D., M.R.C.P., D.P.H. Q(>

FoUR major classes of lipid are found in human serum: cholesterol and its esters, triglyceride, phospholipids and non-esterified fatty acids. They exist in aqueous solution because they are com-bined with protein to form lipoprotein complexes. The non-esterified fatty acids are bound to albu-min, and the other lipids are associated with cer-tain serum globulins. The nomenclature of the lipoproteins derives from the methods used for their separation. The simplest method is paper electrophoresis (Salt & Wolff, 1957; Fredrickson, Levy & Lees, 1967a) and using this technique fou