Screening early renal failure: cut-off values for serum creatinine as an indicator of renal impairment.

Background: The aim of this study was to define cut-off values for serum creatinine as an indicator of several levels of renal impairment.
Methods: To identify the suitable values, receiver operating characteristic curves were constructed based on the data of 984 laboratory assessments of renal function. The glomerular filtration rate was measured with inulin clearance. Three levels of renal impairment were analyzed. An index that gave the same weight to false positive and false negative results was used to determine the thresholds. Robustness of the results was tested using a "bootstrap" technique.
Results: Considering an inulin clearance of less than 80 ml/min/1.73 m2, the cut-off value for serum creatinine was 11.5 mumol/liter for men and 90 mumol/liter for women. The cut-off value for a clearance of less than 60 ml/min/1.73 m2 was 137 mumol/liter for men and 104 mumol/liter for women. For a clearance of less than 30 ml/min/1.73 m2, the cut-off value was 177 mumol/liter for men and 146 mumol/liter for women.
Conclusion: This method is useful to determine a cut-off value for serum creatinine in epidemiological studies concerning early chronic renal failure screening. The value of the glomerular filtration rate of reference and the weight of false positive and false negative results have to be adapted to the aim of the individual study design.