[Determination of the serum concentration of lipoproptein x (author's transl)]

Lipoprotein X (LPX) is a cholestase marker. The authors wish to set forth a simple and quick method for the quantity determination of this abnormal--a method which could be combined with other biochemical tests permitting the demonstration and monitoring of a cholestatic syndrome. The phospholipid composition of lipoprotein X is thought to be constant; therefore, the proposed method of quantity determination consists in an enzymatic quantity determination of phospholipids, performed on the lipoprotein, isolated from the normal serum lipoproteins by means of a simple operative protocol: elimination of the LDL and VLDL by means of immuno-precipitation, followed by separation of the HDL by means of the action of phosphotungstate. In addition to its quantitative characteristic, the proposed method has been shown to be more selective than the traditional demonstration which uses electrophoresis on agar. This electrophoretic research can in effect, show itself to be negative if practised on biological samples which are rich in biliary acids or free fatty acids; conversely, the operative protocol described permits the demonstration of the quantification of lipoprotein X.