8.2 Glomerular Filtration Rate by Creatinine and Cystatin C Measurements in Essential Hypertensive Patients
Introduction. In spite of the adoption of new equations to estimate glomerular filtration rate (GFR), it is very difficult to estimate GFR in patients with different stages of chronic kidney disease.
Aim. To test the reliability of plasma cystatin C to reflect GFR estimation.
Methods. The radionuclide clearance measurement for the assessment of GFR was considered as gold standard. The radioisotopic GFR was compared with the GFR estimation by creatinine clearance, Cockcroft & Gault, C&G/BSA formulas, and Mayo Clinic and MDRD equations and with five equations using plasma cys CGFR was assayed by radionuclide clearance in 110 essential hypertensive patients in basal conditions. Plasma creatinine (Jaff`e reaction) and plasma cystatin C (nephelometric method) were assayed. GFR estimating equations were: for creatinine its clearance, Cockcroft & Gault, C&G/BSA, Mayo Clinic and MDRD equation s; for cystatin C Perkins, Rule, Tan MacIsaac, Arnal-Dade equations. Patients with acute inflammation, tumour and thyroid disease were excluded.
Results. In all hypertensive patients plasma cys C correlated with GFR estimated by radioisotopic method (r = -0.55, p<0.0001). Radioisotopic GFR was significantly correlated with GFR estimated by the four cys C equations (p<0.0001, respectively). Moreover, significant correlations of eGFR by C&G and MDRD equations with radioisotopic GFR (p<0.0001, respectively) were observed. No significant correlation of radioisotopic GFR and Mayo clinic GFR estimation was found. Successively, the power of both cys C and serum creatinine to predict reduced GFR was assayed by ROC curve. Cys C showed higher sensitivity than creatinine (92% Auc 0.86 vs 82.5 AUC 0.74) in predicting GFR < 90 ml/min.
Conclusions. In essential hypertensive patients with chronic kidney disease, especially in the early stage, GFR estimation with MDRD, C&G equations and with cystatin C equations correlated significantly with radioisotopic GFR. On the contrary, mean values of plasma cystatin C showed greater significance than mean values of plasma creatinine as predictors of kidney dysfunction.
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Cottone, S., Guarneri, M., Riccobene, R. et al. 8.2 Glomerular Filtration Rate by Creatinine and Cystatin C Measurements in Essential Hypertensive Patients. High Blood Press Cardiovasc Prev 15, 258 (2008). https://doi.org/10.1007/BF03263670