Influence of ethnicity on population reference values for biochemical markers

Reference intervals (RIs) for biochemical and hematological markers determined using healthy adult and/or pediatric populations are vital for clinical interpretation of laboratory test results. Most clinical laboratories commonly use age- and sex-specific RIs, but the effect of ethnicity as a covariate is often overlooked. Ethnic differences in serum biomarker concentrations can occur as a result of genetic and environmental factors, while the degree to which each factor influences serum levels depends on the specific biomarker. Numerous studies have investigated ethnic differences in routine chemistry, fertility, endocrine, cancer, and hematological markers, as well as in vitamins and carotenoids, in children, adolescents and adults. In the present review, we summarize and discuss ethnic-specific differences observed for these laboratory markers and their potential impact on the clinical interpretation of laboratory test results. We categorized the available data into seven major ethnic groups (i.e. Black, Caucasian, East Asian, Hispanic, South Asian, South East Asian, and West Asian) for ease of comparison. While certain biomarkers could not be compared between ethnic groups because of insufficient information or contradictory results between studies, significant differences between ethnic groups were reported by one or more studies for most of the biomarkers included in this review. The clinical significance of these differences and the potential need for ethnic-specific RIs for certain biochemical markers are also discussed.