Pre and post analytical errors in lipid determination

A number of pre analytical variables affect lipid determinations. These include posture during blood sampling, the duration of tourniquet application and fasting, the time of day when blood is collected, the concentration and type of anticoagulant used for blood collection to name just a few. Effect of life style such as diet, alcohol and caffeine consumption, smoking, and exercise influence lipid determinations. Disease states such as infection, diabetes, nephrotic syndrome and heart disease culminating in myocardial infarction and conditions such as obesity and pregnancy influence lipid profiles. A variety of drugs ranging from diuretics to oral contraceptives to immunosuppressive drugs induce alterations in the patient's lipid profile. Post analytical variables impacting on the interpretation of laboratory data such as in the determination of the true mean of a lipid constituent would depend on the number of specimens analyzed, the analytical variability of the method and approaches to handling data such as the use of relative range to estimate the effect of biological variability on the computed mean value.