Descriptive analytical data and consequences for calculation of common reference intervals in the Nordic Reference Interval Project 2000

Abstract

In the Nordic Reference Interval Project (NORIP), data from 102 Nordic clinical chemical laboratories were obtained. Each laboratory reported analytical data on up to 25 of the most commonly used clinical biochemical properties, including results from each of a minimum of 25 reference individuals. A reference material consisting of a liquid frozen pool of serum with values traceable to reference methods (used as the project "calibrator" for non-enzymes to correct reference values) was measured together with other serum pool controls in each laboratory in the same analytical series as the project samples. The data on the controls were used to evaluate the analytical quality of the routine methods. For reference interval calculations, only such reference values on enzymes were accepted that were obtained by applying the International Federation of Clinical Chemistry (IFCC) compatible methods (37 degrees C), while "calibrator"-corrected reference values were used in the cases of non-enzymes. For each property, gender- and age-specific reference intervals were estimated, based on simple non-parametric calculations and using objective criteria to perform partitioning into subgroups. It is concluded that the same reference intervals are applicable in all five Nordic countries. The following descriptive data for the considered properties are presented in the tables: number of measurement values from each country and measurement system, certified/indicative target values for controls, differences between methods and measurement systems together with coefficients of variation, effects of control correction on the measurement values, differences between subgroups as determined by age, gender, country and material, and comparison of the new reference intervals with those presented in standard textbooks. The 25 components involved in this project were (listed in alphabetical order): Alanine transaminase, albumin, alkaline phosphatase, amylase, amylase pancreatic type, aspartate transaminase, bilirubin, calcium, carbamide, cholesterol, creatine kinase, creatininium, gamma-glutamyltransferase, glucose, HDL-cholesterol, iron, iron-binding capacity, lactate dehydrogenase, magnesium, phosphate, potassium, protein, sodium, triglyceride and urate.

Reference Intervals for Serum Creatinine Concentrations: Assessment of Available Data for Global Application

“…Table 1 compares results from published studies evaluating reference intervals for serum creatinine concentrations in adults obtained with methods traceable to the reference system (19 -22 ). The data obtained by Mazzachi et al (20 ) and Rustad and colleagues (21,22 ) are quite similar to those of Junge et al (19 ). In the populations studied by these investigators (all white individuals), the reference intervals appear to be very similar from Northern Europe to Australia.…”

“…Only 1 of these dealt with the pediatric population (12 ). Three were on the same group of subjects and can be considered together (21)(22)(23). All these reports were found to comply with all the criteria and obtained very similar results (Table 1), but we selected the report of Junge et al (19 ) for final consideration because it gave a better description of the experiments performed to demonstrate traceability of the results.…”

Whether western normative laboratory values used for clinical diagnosis are applicable to Indian population? An overview on reference interval

“…A very successful Nordic reference interval project on common reference intervals with a team of Nordic countries was initiated in the year 2000 and supported by Scandinavian Society of Clinical Chemistry (NFKK) (69,70 Each laboratory was instructed to collect serum, plasma and whole blood samples from a minimum of 25 reference individuals comprising of healthy personnel and their healthy adult family members. Each reference individuals were asked to fill out a questionnaire.…”

Mode of oral iron administration and the amount of iron habitually consumed do not affect iron absorption, systemic iron utilisation or zinc absorption in iron-sufficient infants: a randomised trial

“…Hb and mean corpuscular volume were measured in whole blood using a Sysmex XE-5000 Automated Haematology Analyser (Sysmex). Blood in the serum separator tube was centrifuged for 10 min at 3000 rpm, and the separated serum was analysed for ferritin using a Roche Cobas 6000 (Roche Diagnostics), and Fe and transferrin were analysed using a Serum Fe and transferrin concentrations were used to calculate transferrin saturation using the following formula: transferrin saturation (%) = serum Fe (μmol/l)/(serum transferrin (g/l) × 25·1) × 100 (43) . The remaining serum was stored at −80°C until hepcidin and high-sensitivity C-reactive protein analyses.…”