[Show abstract][Hide abstract] ABSTRACT: Race and ethnicity are influential in estimating glomerular filtration rate (GFR). We aimed to find the Korean coefficients for the Modification of Diet in Renal Disease (MDRD) study equations and to obtain novel proper estimation equations. Reference GFR was measured by systemic inulin clearance. Serum creatinine (SCr) values were measured by the alkaline picrate Jaffé kinetic method, then, recalibrated to CX3 analyzer and to isotope dilution mass spectrometry (IDMS). The Korean coefficients for the 4 and 6 variable MDRD and IDMS MDRD study equations based on the SCr recalibrated to CX3 and to IDMS were 0.73989/0.74254 and 0.99096/0.9554, respectively. Coefficients for the 4 and 6 variable MDRD equations based on the SCr measured by Jaffé method were 1.09825 and 1.04334, respectively. The modified equations showed better performances than the original equations. The novel 4 variable equations for Korean based on the SCr measured and recalibrated to IDMS were 107.904×SCr(-1.009)×age(-0.02) (×0.667, if woman) and 87.832×SCr(-0.882)×age(0.01) (×0.653, if woman), respectively. Modified estimations of the MDRD and IDMS MDRD study equations with ethnic coefficients and the novel equations improve the performance of GFR estimation for the overall renal function.
Journal of Korean medical science 11/2010; 25(11):1616-25. · 0.84 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Although cystatin C has been developed as an alternative marker for estimating glomerular filtration rate (GFR), its clinical use is as yet limited. The significance of cystatin C for differentiating chronic kidney disease (CKD) stages and established cystatin C-based equations estimating GFR were evaluated.
The fresh frozen serum samples from CKD (n = 119) and healthy volunteers (n = 22) were evaluated. Serum creatinine (sCr) was measured by the kinetic Jaffé method, and recalibrated to the isotope dilution mass spectrometry (IDMS). Cystatin C was measured using a particle-enhanced nephelometric assay.
CKD stages were more sensitively differentiated by cystatin C compared to sCr, especially in moderate and severe kidney dysfunction. Sex and body mass index did not affect cystatin C level. Pearson's correlation coefficients of reciprocal of cystatin C, measured and recalibrated sCr compared to systemic inulin clearance (Cl(in) ) were 0.757, 0.734 and 0.709, respectively. We derived novel pertinent equations based on cystatin C (model 1: 1.404 × cystatin C(-0.895) × age(0.006) × weight(1.074) × height(-1.562) × (0.865; if female); model 2: 43.287 × cystatin C(-0.906) × age(0.101) × (0.762; if female)]. Models 1 and 2 showed superior performance in representing systemic Cl(in) than the IDMS Modification of Diet in Renal Disease (MDRD) study equations did (adjusted r(2) = 0.76 and 0.72 for models 1 and 2, and 0.64 and 0.65 for 4 and 6 variable IDMS MDRD equations, respectively). Conclusion: Cystatin C reflects kidney dysfunction sensitively, and thus cystatin C-based estimation of GFR could provide a reliable support for clinical practice.