Objective: Glomerular filtration rate is one of the best indicators of renal function. It is usually determined indirectly by calculating renal clearance of endogenous filtration markers creatinine or urea. In addition, different formulas have been developed for determining creatinine clearance using serum creatinine level, age, race, gender and body surface area. The aim of this study is to compare creatinine clearance and the calculated glomerular filtration rate with MDRD (Modification of Diet in Renal Disease) formula.

Materials and Methods: Four hundred fifty people (260 women, 190 men), aged between 18 and 87 years, who applicant to the Uludag University Central Laboratory were included in this study. Participants were divided into subgroups according to gender, MDRD values and age. Creatinine clearance was calculated by 24-hour urine and serum creatinine concentrations measured with the Jaffe method. Simultaneously glomerular filtration rate was calculated by the MDRD equation.

Results: MDRD and creatinine clearence values were significantly different in the whole study group and there was a significant positive correlation (r= 0.809, p<0.001) between creatinine clearance and glomerular filtration rate calculated by the MDRD equation. And also we found a statistically significant difference between MDRD and creatinine clearance in all group (p<0.001). Subgroups analyzed according to MDRD, in the subgroup with MDRD <90 ml/min/1.73 m2, the correlation was found to be weaker than in the other subgroups. Correlation between two parameters were also lower than other age subgroups in patients aged between 50-64.

Conclusion: Glomerular filtration rate values that obtained by creatinine clearance and MDRD are different in under the age of 65 and the values of <90 mL/min/1.73 m2; however there was a significant correlation between these two parameters which promotes to be practical and advantageous pre-assessment method particularly for the purpose of screening.