At GFR <60 ml/min, CKD-EPI and Hoek equations appeared to best correlate with (99m)TcDTPA. In controls and at early stages of CKD, creatinine-based equations correlated better with (99m)Tc-DTPA, with CKD-EPI being the one with the best degree of agreement.

Background. Precise estimation of the glomerular filtration rate (GFR) and the identification of markers of progression are important. We compared creatinine, cystatin, and combined CKD-EPI equations with 99mTc-DTPA scintigraphy to measure GFR and proteinuria as markers of progression. Methods. Cross-sectional, observational study including 300 subjects. CKD was classified by 99mTc-DTPA scintigraphy. Determinations. Creatinine, 24-hour creatinine clearance, cystatin, Hoek formula, and creatinine, cystatin, and combined CKD-EPI equations. Results. In the global assessment, creatinine CKD-EPI and combined CKD-EPI equations yielded the highest correlations with 99mTc-DTPA: ρ = 0.839, P < 0.0001 and ρ = 0.831, P < 0.0001. Intergroup analysis versus 99mTc-DTPA: control G, creatinine clearance ρ = 0.414, P = 0.013; G3, combined CKD-EPI ρ = 0.5317, P < 0.0001; G4, Hoek ρ = 0.618, P < 0.0001, combined CKD-EPI ρ = 0.4638, P < 0.0001; and G5, creatinine clearance ρ = 0.5414, P < 0.0001, combined CKD-EPI ρ = 0.5288, P < 0.0001. In the global assessment, proteinuria displayed the highest significant correlations with cystatin (ρ = 0.5433, P < 0.0001) and cystatin-based equations (Hoek: ρ = −0.5309, P < 0.0001). When GFR < 60 mL/min: in stage 3, proteinuria-cystatin (ρ = 0.4341, P < 0.0001); proteinuria-Hoek (ρ = −0.4105, P < 0.0001); in stage 4, proteinuria-cystatin (ρ = 0.4877, P < 0.0001); proteinuria-Hoek (ρ = −0.4877, P = 0.0026). Conclusions. At every stage of GFR < 60 mL/min, cystatin-based equations displayed better correlations with 99mTc-DTPA. Proteinuria and cystatin-based equations showed strong associations and high degrees of correlation.