Laboratory testing and biochemical analysis of hyperlipidaemias

In establishing the accuracy of cholesterol measurements, attention must be devoted to aspects of the pre-analytical phase, such as preparation of the patient and type of specimen used. Cholesterol measurement is most accurately performed by means of a gas chromatographic-mass spectrometric procedure, while most clinical laboratories use an enzymatic method. Lipoprotein fractionation techniques vary, from simple precipitation used to determine HDL cholesterol to ultracentrifugation. The most widely used procedure for estimating LDL cholesterol depends on the use of the Friedewald formula. Methods for measuring triglycerides are not as well developed as those for cholesterol and no reference method has yet been established. However, there is recent evidence that home monitoring of triglyceride levels in diabetic subjects using a Reflotron can encourage a reduction in triglyceride levels. This review concludes with a discussion of the measurement of apolipoproteins and the more complex investigation of specific hyperlipidaemias. It seems that techniques from molecular biology, such as the use of the polymerase chain reaction, will find increasing use in the assessment of hyperlipidaemias in the future.