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BACKGROUND: Reference intervals for serum creatinine remain relevant despite the current emphasis on the use of the estimated glomerular filtration rate for assessing renal function. Many studies on creatinine reference values have been published in the last 20 years. Using criteria derived from published IFCC documents, we sought to identify universally applicable reference intervals for creatinine via a systematic review of the literature.
METHODS: Studies were selected for inclusion in the systematic review only if the following criteria were met: (a) reference individuals were selected using an "a priori" selection scheme, (b) preanalytical conditions were adequately described; (c) traceability of the produced results to the isotope dilution-mass spectrometry (IDMS) reference method was demonstrated experimentally, and (d) the collected data received adequate statistical treatment.
RESULTS: Of 37 reports dealing specifically with serum creatinine reference values, only 1 report with pediatric data and 5 reports with adult data met these criteria. The primary reason for exclusion of most papers was an inadequate demonstration of measurement traceability. Based on the data of the selected studies, we have collated recommended reference intervals for white adults and children.
CONCLUSION: Laboratories using methods producing traceable results to IDMS can apply the selected reference intervals for serum creatinine in evaluating white individuals.
© 2008 American Association for Clinical Chemistry
The usefulness of plasma or serum creatinine measurements for the identification of renal insufficiency is hampered by its covariation with sex, age, race, diet, and muscle mass of each individual in whom it is being measured (1, 2). Moreover, the analytical quality of the test is often suboptimal due to the nonspecificity of the Jaffe method used in most routine laboratories (3).
The recent campaign of the National Kidney Disease Education Program, initiated in 2000 by the US National Institutes of Health (4 ), has led to increased focus on the measurement of creatinine in serum (5). Concurrently, there has been an international effort to improve creatinine standardization by assuring traceability to the reference system (6 ). These efforts highlighted limitations of commercially available methods for creatinine measurement as well as the differences in results among methods resulting from a lack of assay standardization and the nonspecificity of the alkaline picrate method used in the majority of clinical laboratories (3, 7,8). A...