Towards common reference intervals in clinical chemistry - An attempt at harmonization between three hospital laboratories in Skane, Sweden

The population sample of the Kristianstad survey, a reference intervals sur vey in the county of Kristanstad, was used to establish new reference inter vals in clinical chemistry at the laboratories of the Central Hospital in K ristianstad, the University Hospital in Lund and the University Hospital in Malmo. Three-hundred and fifty nine subjects, male and female, aged 20-80+ years, were invited to participate in the study, with a participation rate of 70 % . Up to 70 analyses were performed on each subject, general clinical chemis try parameters in ail three laboratories, specialized analyses where availa ble. Separate a priori exclusion criteria were defined for each test. In ad dition, the test pattern of each individual was evaluated for signs of prec linical disease. Twelve cases of preclinical disease were discovered and cl inically confirmed. Details on all test methods are presented along with information concerning instruments used, calibration procedures, methods of calculation and obtai ned reference intervals. Although the methods were in general calibrated ag ainst acknowledged reference materials, in some instances differences were found that made common reference intervals across all laboratories impossib le. Problems relating to the practical use of international recommendations and the establishment of reliable reference intervals are discussed.