Examination of Serum Total Cholesterol Reference Limits with Outlier Analysis: A Methodological Study

Abstract

Objective: High serum cholesterol levels increase the risk of cardiovascular disease. Serum cholesterol reference values are important in determining the risk. The aim of this article is to evaluate the reference limits for serum total cholesterol using the outlier approach. Material and Methods: In this study, Box-Plot method was used to find limit values for total cholesterol. The method was preferred because it does not require excessive statistical knowledge, does not require the use of statistical tables, and is easy to interpret and apply. The data were obtained retrospectively by using the archival data of a total of 42,185 individuals, 24,782 females aged 1-93 years, 17,403 males aged 1-97 years, who were admitted to a university hospital out-patient clinic for any reason between January 1, 2023 and December 11, 2023, some of whom were diagnosed and some of whom were not diagnosed after admission. Results: According to the findings, the classification and limits of total serum cholesterol value for male adolescents were determined as ?62 low, 63-169 acceptable, 170-199 borderline high, 200-228 high and ?229 very high. For adult males, these limits are ?55 low, 56-199 acceptable, 200-239 borderline high, 240-289 high, and ?290 very high, respectively. For adolescent female were defined as ?71 low, 72-169 acceptable, 170-199 borderline high, 200-225 high, and?226 very high. For adult female, these limits are ?72 low, 73-199 acceptable, 200-239 borderline high, 240-295 high, and?296 very high, respectively. Conclusion: Although cut-off values are used in clinical evaluations, upper and lower reference values should also be considered. The reference limits obtained from the study for serum total cholesterol are clearer and more specific values that physicians can use for diagnosis. © 2025 by Türkiye Klinikleri.