The Effects of Pre-analytical Variables on the Diagnosis of Inborn Errors of Metabolism; A Review Study

Quantitative metabolite profiling in biological samples has the potential to reflect physiological status and to identify disease associated disorders in metabolic pathways. This approach is hindered by a wide range of pre-analytical variables. Pre-analytical variables account for 32-75% of laboratory errors, which includes the time from when the test is ordered by the physician until the sample is ready for analysis. The aims of this study was to evaluate the pre-analytical errors in diagnostic methods of inherited metabolic disorders. In this study, 35 articles with the key words Pre-analytical Errors, Metabolic disorders, Samples, Mass Spectrometry, and Gas Chromatography were searched in PubMed, Google Scholar, and Scopus databases from the year 1987 to 2018. There are some less controllable sources of pre-analytical errors that can strongly influence the reliability of test results in inborn errors of metabolism. These primarily include specimen collection, handling samples and physiological variables such as the effect of lifestyle, diet, stress, age, gender, positional effects, and endogenous variables such as drugs and circulating antibodies. As pre-analytical sources of variation can produce unpredictable and unfavorable impacts on the wellbeing of patients, a reduction in laboratory testing errors play a significant role in assessing and quality improvements. In this respect, good quality specimens, resulting from proper training and knowledge about effective factors on laboratory results, are essential for minimizing errors and optimizing resource utilization and whole patient management process to assure accurate diagnosis.