Establishment of reference intervals of clinical chemistry analytes for the adult population in Egypt

Abstract

Background This is the first Egyptian nationwide study for derivation of reference intervals (RIs) for 34 major chemistry analytes. It was conducted as a part of the global initiative by the IFCC Committee on Reference Intervals and Decision Limits (C-RIDL) for establishing country-specific RIs based on a harmonized protocol. Methods 691 apparently healthy volunteers aged ≥18 years were recruited from multiple regions in Egypt. Serum specimens were analyzed in two centers. The harmonization and standardization of test results were achieved by measuring value-assigned serum panel provided by C-RIDL. The RIs were calculated by parametric method. Sources of variation of reference values (RVs) were evaluated by multiple regression analysis. The need for partitioning by sex, age, and region was judged primarily by standard deviation ratio (SDR). Results Gender-specific RIs were required for six analytes including total bilirubin (TBil), aspartate and alanine aminotransferase (AST, ALT). Seven analytes required age-partitioning including glucose and low-density lipoprotein cholesterol (LDL-C). Regional differences were observed between northern and southern Egypt for direct bilirubin, glucose, and high-density-lipoprotein cholesterol (HDL-C) with all their RVs lower in southern Egypt. Compared with other collaborating countries, the features of Egyptian RVs were lower HDL-C and TBil and higher TG and C-reactive protein. In addition, BMI showed weak association with most of nutritional markers. These features were shared with two other Middle Eastern countries: Saudi Arabia and Turkey. Conclusion The standardized RIs established by this study can be used as common Egyptian RI, except for a few analytes that showed regional differences. Despite high prevalence of obesity among Egyptians, their RVs of nutritional markers are less sensitive to increased BMI, compared to other collaborating countries.

Establishment of reference intervals for hematological parameters of adult population in the western region of Saudi Arabia

“…We adopted a secondary criterion termed bias ratio (BR) at LL (or BR LL ) and at UL (or BR UL ) to determine the need for partitioning RVs since we occasionally meet situations where the SDR does not represent a true between-subgroup variation at the lower or upper bounds (LL, UL) of the RI [ 26 , 27 ]. This is defined by the following formula illustrated for sex partitioning: where subscript M, F, and MF represent male, female, and male + female, respectively.…”

“…the SDR does not represent a true between-subgroup variation at the lower or upper bounds (LL, UL) of the RI [26,27]. This is defined by the following formula illustrated for sex partitioning:…”

Establishment of reference interval for hemoglobin A1C and other hemoglobin subfractions for healthy Saudi adults

“…The SDR may not show true variability between subgroups, especially at the lower or upper RI limits (LL, UL). Therefore, a secondary criterion called bias ratio (BR) to lower limit (BR LL ) and upper limit (BR UL ) was used to determine the need to split RV [ 55 , 56 ].…”

Cohort Profile: Swiss BioRef: The building blocks of a nationwide IT infrastructure in Switzerland for generating precise reference intervals

“…for the nomenclature, terminology, units and formats used, to ensure reproducibility of all the steps of the total laboratory testing procedure, possibly for international application [10,11]. This is an on-going global process, as laboratories in Europe [12][13][14][15][16][17], Africa [18][19][20], North America [21], Asia [22][23][24] and Australia [25] aim to derive nation-specific RIs with multicentre studies. Despite this welcome effort, most studies have been conducted with very lenient inclusion/exclusion criteria due to a missing overarching definition of "health", covering both the normative aspects (well-being and functioning) and more descriptive aspects of health evaluation (test result assessment).…”

“…for the nomenclature, terminology, units and formats used, to ensure reproducibility of all the steps of the total laboratory testing procedure, possibly for international application[10,11]. This is an on-going global process, as laboratories in Europe[12–17], Africa[18–20], North America[21], Asia[22–24] and Australia[25] aim to derive nation-specific RIs with multicentre studies.…”