Limitations of estimating glomerular filtration rate from serum creatinine in the general population

OBJECTIVE: To compare estimated glomerular filtration rate (GFR) In the general population on the basis of equations derived from different subsets of the general population. PARTICIPANTS AND METHODS: Admits (ages ≥45 years) were randomly selected from 1997 to 2000 from the Olmsted County, Minnesota, population and had their serum creatinine levels measured. The GFR was estimated using previously reported equations derived tram a sample of patients with chronic kidney disease (CKD), a sample of healthy persons, and the combined samples. Serum creatinine was measured with the same assay used to derive these equations. RESULTS: Of 4203 subjects, 2042 (47% participation rate) were enrolled and studied. Serum samples from 1982 subjects were used to measure creatinine ievels. The prevalence of a reduced estimated GFR (<60 mL/min per 1.73 m²) was 12% (95% confidence Interval [CI], 10%-13%) based on an equation derived with all CKd patients, and this finding was similar to prior reports. However, the prevalence of a reduced estimated GFR was 5.7% (95% CI, 4.8%-6.8%) based on an equation derived with both CKD patients and healthy persons and 0.2% (95% CE, 0.1%-0.5%) based on an equation derived with all healthy persons. Women had a higher risk of reduced estimated GFR according to an equation derived with all CKD patients, but men had a higher risk with an equation derived with both CKD patients and healthy persons. CONCLUSION: The use of serum creatinine to diagnose CKD requires a different approach (eg, normal value study) from the use of serum creatinine to estimate GFR once the diagnosis of CKD has been made.