Need for Estimating the Glomerular Filtration Rate to Assess Renal Function

Background: plasma creatinine alone is not useful for assessing renal function; patients with normal creatinine values can experience a significant decline in the glomerular filtration rate, hindering early detection of renal function impairment. Objective: to assess renal function by determining the plasma creatinine compared to the glomerular filtration rate estimated through the Cockcroft-Gault, MDRD-4 and CKD-Epi formulas. Methods: the database of a population-based epidemiological study conducted in the Isle of Youth since November 2004 was used. It involved 897 patients, 342 women and 555 men. Plasma creatinine and glomerular filtration rate were estimated by means of 3 formulas. Renal function was considered normal when serum creatinine values were < 123 mu mol/l for women and < 132 mu mol/l for men and glomerular filtration rate > 60 ml/min. Results: plasma creatinine was stable in the four age groups, with a mean of 100.68 +/- 38.01, glomerular filtration rate decreased with increasing age in the three formulas. Correlation coefficient between plasma creatinine values and glomerular filtration rate for each formula expressed a linear relationship with r [CG formula 0.639 (p = 0.000)], [0.672 MDRD-4 (p = 0.000)] and [0.939 CKD -Epi formula (p = 0.000)]. Conclusions: the utility of the methods for estimating the glomerular filtration rate was demonstrated, leading to the detection of the renal function impairment before the serum creatinine level increases.