title: Correlation of plasma concentrations of cystatin C and creatinine to inulin clearance in a pediatric population.
abstract: Measurement of blood concentrations of cystatin C (cysC), a cysteine protease inhibitor present in human plasma, has been suggested for use as an indicator of glomerular filtration rate (GFR) in a manner analogous to the use of plasma creatinine (SCR). In this study, cysC and SCR were measured in plasma from pediatric patients (4-19 years) with renal disease for whom a "gold standard" measurement of GFR via inulin clearance (C(IN)) was available. The data analyses were divided into two age groups: group A (4-12 years, n = 26) and group B (12-19 years, n = 34). For both age groups, the linear correlation coefficient of [cysC](-1) vs C(IN) (mL/min/1.73 m2) (r = 0.765 for group A and r = 0.869 for group B) was less than that of the linear correlation coefficient of [SCR](-1) vs C(IN) (r = 0.841 for group A and r = 0.892 for group B). As a single measurement for detection of abnormal GFR, however, the optimum receiver-operator characteristic point for cysC measurement (for group A at cysC >1.2 mg/L, sensitivity = 80%, specificity = 91%; and for group B at cysC >1.4 mg/L, sensitivity = 87%, specificity = 100%) was numerically superior to that for SCR measurement (for group A at SCR >8.0 mg/L, sensitivity = 67%, specificity = 100%; and for group B at SCR >9.0 mg/L, sensitivity = 91%, specificity = 91%), using a reference value for normal GFR of C(IN) > 90 mL/min/1.73 m2. However, these differences were not statistically significant. CysC measurement appears to be broadly equivalent to SCR measurement for estimation of GFR in pediatric patients.
authors.affiliation: Department of Pathology, Washington University School of Medicine, St. Louis, MO 63110-1093, USA.
authors.forename: D
authors.initials: D
authors.lastname: Stickle
authors.forename: B
authors.initials: B
authors.lastname: Cole
authors.forename: K
authors.initials: K
authors.lastname: Hock
authors.forename: K A
authors.initials: KA
authors.lastname: Hruska
authors.forename: M G
authors.initials: MG
authors.lastname: Scott
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D003404:Creatinine / Q000097:blood*; D055316:Cystatin C; D015891:Cystatins / Q000097:blood*; D005919:Glomerular Filtration Rate; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007444:Inulin / Q000493:pharmacokinetics; D007674:Kidney Diseases / Q000097:blood / Q000503:physiopathology; D011237:Predictive Value of Tests
chemical_list: C525030:CST3 protein, human; D055316:Cystatin C; D015891:Cystatins; D007444:Inulin; D003404:Creatinine