Journal of Clinical and Scientific Research

: 2021  |  Volume : 10  |  Issue : 2  |  Page : 131--132

Fasting samples for biochemical analysis-changing concepts

Naresh Yajamanam 
 Department of Biochemistry, Santhiram Medical College, Kurnool, Andhra Pradesh, India

Correspondence Address:
Naresh Yajamanam
Associate Professor, Santhiram Medical College, Kurnool, Andhra Pradesh - 518001

How to cite this article:
Yajamanam N. Fasting samples for biochemical analysis-changing concepts.J Clin Sci Res 2021;10:131-132

How to cite this URL:
Yajamanam N. Fasting samples for biochemical analysis-changing concepts. J Clin Sci Res [serial online] 2021 [cited 2021 Sep 23 ];10:131-132
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One of the important components of pre-analytical phase during biochemical testing of plasma/serum is the status of the patient with respect to food intake. The concentration of several analytes was found to vary with the time interval between food intake and collection of blood sample. These include many of the commonly asked parameters. After a meal, triglycerides, albumin, uric acid, alkaline phosphatase, calcium, iron and sodium levels increase, whereas blood urea nitrogen and phosphate levels decrease. The variations observed are clinically significant in case of triglycerides, albumin, calcium, sodium and uric acid levels. Thus, a significant variation can occur in the clinical chemistry parameters after a regular meal.[1] A meal can affect the concentration of the analytes by virtue of its composition and/or due to lipemia, especially after the ingestion of a fatty meal which causes errors during analysis by interference. It was also reported that even after fasting, biochemical measurements may still differ in relation to fasting duration and time of day. It was suggested that the fasting time be considered when performing blood testing so as to prevent spurious results and reduce laboratory errors. This further strengthens the importance of obtaining a standardised morning fasting sample.[2],[3]

However, there are some concerns about obtaining a fasting sample. These include patients' concepts and awareness about fasting, lack of uniform guidelines and recommendations available with respect to fasting requirements, difficulties faced in case of patients with chronic illnesses such as diabetes mellitus and children. This necessitated exploring the possibility of using a non-fasting sample for clinical chemistry parameters.[4],[5],[6],[7]

Recently, the European Atherosclerosis Society and European Federation of Clinical Chemistry and Laboratory Medicine in a joint consensus statement have recommended the routine use of non-fasting blood samples for the assessment of plasma lipid profiles.[8] Another report also recommends use of non-fasting sample for lipid profile stating that non-fasting lipid profiles do not have negative implications for prognostic, diagnostic and therapeutic options for cardiovascular disease prevention. This recommendation is likely to increase patient compliance towards testing as it is practically more convenient and also safe, avoiding episodes of hypoglycaemia, especially in diabetes patients on treatment.[9]

Although the usage of non-fasting samples for testing lipid profile is being recommended, the traditional concept of fasting specimens is still followed by many laboratories. Despite the fact that it provides more convenience to the patients resulting in improved patient compliance, the use of non-fasting sample needs further exploration before it can be brought into routine practice. Still non-fasting sample recommendations confined to lipid profile and are largely based on lack of impact of the errors on evaluation of cardiovascular risk.[8],[9] Thus, while the use of non-fasting sample for lipids is getting acceptance, there are certain implications to be considered. The recommendations are from a cardiovascular risk assessment point of view. Follow-up of patients on anti-lipid drugs may still be better with a standardised morning fasting sample. The reports cover only some parts of the world whereas the food habits vary widely among various countries. There are sparse data on this from India.

Similar studies like what has been done for lipid profile have to be conducted to understand better the clinical implications of variations in biochemical parameters with use non-fasting sample. Till such time, it may be better that both the physicians and laboratories continue with the current fasting evaluations ensuring appropriate patient preparation for all clinical evaluations and treatment options. Thus, a fasting sample still appears to be a preferred sample till all the concerns associated with a non-fasting sample such as interferences during analysis and the likely variations in the concentration of certain analytes which may cause difficulty in interpretation of the results are understood completely.

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