Reference values for 27 clinical chemistry tests in 70-year-old males and females.

BACKGROUND Reference values are usually defined based on blood samples from healthy men or nonpregnant women in the age range of 20-50 years. These values are not optimal for elderly patients, as many biological markers change over time and adequate reference values are important for correct clinical decisions. OBJECTIVE To validate NORIP (Nordic Reference Interval Project) reference values in a 70-year-old population. METHODS We studied 27 frequently used laboratory tests. The 2.5th and 97.5th percentiles for these markers were calculated according to the recommendations of the International Federation of Clinical Chemistry on the statistical treatment of reference values. RESULTS Reference values are reported for plasma alanine aminotransferase, albumin, alkaline phosphatase, pancreas amylase, apolipoprotein A1, apolipoprotein B, aspartate aminotransferase, bilirubin, calcium, chloride, cholesterol, creatinine, creatine kinase, C-reactive protein, glucose, gamma-glutamyltransferase, HDL-cholesterol, iron, lactate dehydrogenase, LDL-cholesterol, magnesium, phosphate, potassium, sodium, transferrin, triglycerides, urate and urea. CONCLUSION Reference values calculated from the whole population and a subpopulation without cardiovascular disease showed strong concordance. Several of the reference interval limits were outside the 90% CI of a Scandinavian population (NORIP).