Reference range study and values verification for different biochemistry parameters in Gaziantep region with the indirect method

Reference intervals are an important part of clinical decision making. These intervales reported by laboratories are used by clinicians in interpreting patients's test results. Therefore, establishing reliable intervals is an important task for laboratories. In this study, we aimed to create a reference interval for 30 tests retrospectively using the indirect method using outpatient data from Gaziantep University Şahinbey Research and Practice Hospital between the years 2015-2021. In addition, we planned to make a verification to determine the suitability of transferring the reference intervals we obtained to our laboratory. The data of outpatients admitted to our hospital were selected according to certain criteria. Total protein, albumin, urea, uric acid, creatinine, total bilirubin, direct bilirubin, glucose, triglyceride, HDL-C, LDL-C, total cholesterol, sodium, potassium, chlorine, calcium, phosphorus, magnesium, AST, ALT, LDH, ALP, GGT, CK, amylase, iron, insulin, TSH, fT4, fT3 tests were used. For verification, 80 volunteers whose health status was determined by questionnaire were included in the study. The Bhattacharya and Tukey method was used to determine the reference intervals with patient data. The percentage of the tests within the reference intervals of the reference values obtained from healthy volunteers for verification and the marking rates of the patient data according to these intervals were determined. When the reference intervals we obtained were evaluated, it was seen that the intervals created by the Tukey method were wider than the intervals obtained by the Bhattacharya method. According to the verification results, it was confirmed that more compatible and comparable reference intervals were obtained with the Bhattacharya method. The indirect method takes its power from the correct selection criteria and the correct application of statistical methods. When these conditions are met, safe reference intervals can be established by indirect method and their usability can be evaluated with verification.