B-140 Reference interval (RI) Estimation: Homocysteine in adults in Brazil, laboratory RI tool in data mining of recipe

Background Homocysteine is an amino acid derived from the metabolism of methionine. Elevated homocysteine levels are associated with an increased risk of atherosclerotic vascular diseases due to their toxic effect on endothelial cells, leading to an increased risk of atherosclerosis, cardiovascular diseases and stroke. The objective was to evaluate the Reference Intervals (RI) described by the manufacturer Siemens® in comparison with the Brazilian Clinical Laboratory Datalake operating in the State of São Paulo, using the LabRI® statistical tool with a combination of parametric, nonparametric and robust statistical algorithms and techniques to exclude latent abnormal values, outliers and estimate reference limits and their respective confidence intervals. Methods A total of 5.205 homocysteine results were obtained within the linear range from routine laboratory tests performed on outpatients aged between 19 and 60 years, and with exclusion criteria predefined by the medical team, they were separated by biological sex, with a total of 2.667 female samples and 2.528 male samples. All results were analyzed using the direct Chemiluminescence method on Siemens® equipment, models Advia Centaur 2400 and Atellica CH. Sample processing followed standardized pre-analytical and analytical criteria controlled by good laboratory practices and current legislation, in addition to being covered by the National Accreditation Standard of the Clinical Laboratory Accreditation Program (PALC) and College of American Patholoists (CAP). Results After statistical processing of the data, we evaluated them separately by sex, where we identified 37 outliers (1.39%) for females and 69 outliers (2.73%) for males, which were detected and excluded, maintaining the mean and median of the results with symmetrical distribution. The RI proposed by the manufacturer was 3.7 to 13.9 µmol/L for both sexes. In the estimation of new RIs, using a 95% confidence interval, the range for females was 6.8 to 18.4 µmol/L and for males 7.9 to 19.0 µmol/L. Conclusion With the definition of a safe statistical tool and multidisciplinary analysis of the results found, the RI provided by the manufacturer was replaced by RIs specific to the adult population served.