The ratio of urinary cystatin C to urinary creatinine for detecting decreased GFR.
Glomerular filtration rate (GFR) and urine and serum concentrations of cystatin C and creatinine were measured in 40 boys and 42 girls. The fractional excretion of cystatin C (FE Cyst C) increased in proportion to the decrease in GFR. Since serum creatinine concentration (S-Creatinine) in the numerator of the fractional excretion equation and serum cystatin C concentration (S-Cystatin C) in the denominator have similar numerical values, they cancel out. The result is an equation in which the FE Cyst C is equal to the ratio of urinary cystatin C to urinary creatinine (u[cystatin-C/Cr]). The ratio of u[cystatin C/Cr] was compared with GFR. Using a receiving operating characteristic (ROC) plot, the data showed that a ratio of u[cystatin C/Cr]*100 that is > or =0.100 has a sensitivity of 90.0% for identification of children with GFR < or =60 ml/min per 1.73 m(2). The false-positive rate is 16.1%. The u[cystatin C/Cr] ratio is a reliable screening tool for detecting decreased GFR that does not require a serum sample.
Hellerstein
Stanley
S
Section of Nephrology at The Children's Mercy Hospital, The University of Missouri School of Medicine at Kansas City, Kansas City, Missouri 64108, USA. shellers@cmh.edu
Berenbom
Max
M
Erwin
Pat
P
Wilson
Nancy
N
DiMaggio
Sylvia
S
D000293:Adolescent; D000328:Adult; D002648:Child; D002927:Cimetidine / Q000627:therapeutic use; D003404:Creatinine / Q000652:urine*; D055316:Cystatin C; D015891:Cystatins / Q000652:urine*; D005189:False Positive Reactions; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006635:Histamine H2 Antagonists / Q000627:therapeutic use; D006801:Humans; D008297:Male; D012372:ROC Curve
C525030:CST3 protein, human; D055316:Cystatin C; D015891:Cystatins; D006635:Histamine H2 Antagonists; D002927:Cimetidine; D003404:Creatinine