Avaliação da cistatina C como marcador de função renal de pacientes com hipertensão arterial primária

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

Essential hypertension is an important risk factor for the development of chronic kidney disease. Accurate monitoring of kidney function, which is the estimation of glomerular filtration rate and determination of the presence of microalbuminuria, is mandatory in order to ensure an adequate evaluation in hypertensive patients. Cystatin C has been proposed as an alternative filtration marker to plasma creatinine. The present study was undertaken to evaluate the use of serum cystatin C (cysC) in detecting early renal involvement in patients with primary hypertension and the association between cystatin C-based equations with other well-known markers of glomerular filtration rate (GFR). For this, a cross-sectional study was performed in 199 non-diabetic patients with essencial hypertension. As an assessment of renal function, serum creatinine, 24-h microalbuminuria, and serum cystatin C levels were measured. The GFR was predicted according to creatinine clearance (CrCl), cystatin C-based equations (i.e. Larsson and Levey formulas), Cockcroft-Gault (C-G) and Modification of Diet in Renal Disease (MDRD) abbreviated equations. The MDRD was used as the reference method according to the current recommendations by KDIGO and NKF-K/DOQI. Mean levels of the serum parameters were found to be statistically lower in normoalbuminurics than in microalbuminurics. Serum cysC was significantly higher in microalbuminurics (1,070,48 mg/L) than in normoalbuminurics (0,860,17; p<0,001). The logistic regression analyses showed that cysC values >0,95 mg/L were significantly associated to the presence of microalbuminuria (OR=3,2; 95% CI, 1,40-7,42; p=0,006). Of the estimations of GFR, significant differences among normoalbuminurics and microalbuminurics were found on CG, Larsson and Levey formulas. The best correlation coefficients were observed between MDRD with the C-G (r=0,66) and Levey formula (r=0,88)(p<0,001). The mean difference, calculated according to Bland-Altman plot analysis, between MDRD equation and Levey formula, was -1,3 mL/min/1,73m2 and the 95% limits of agreement attained -24,1 and 21,4 mL/min/1.73 m2. Our results indicate that serum cysC level is of clinical value for detecting mild reductions and early damages in patients with essential hypertension. Although MDRD equation showed no difference between normoalbuminurics and microalbuminurics, cystatin C-based equations, mainly Levey formula, compared to other traditional markers, can also provide the clinicians an available and reliable GFR measurement in hypertensive patients, specially when the kidney disease is suspected.

ASSUNTO(S)

cistatina c equações equations kidney function função renal glomerular filtration rate creatinina taxa de filtração glomerular cystatin c creatinine ciencias da saude

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