Abstract
Introduction: The use of a simple and accurate glomerular filtration rate (GFR) estimating method aiming minute assessment of renal function can be of great clinical importance. Objectives: This study aimed to determine the association of a GFR estimating by equation that includes only cystatin C (Gentian equation) to equation that include only creatinine (Schwartz equation) among children. Patients and Methods: A total of 31 children aged from 1 day to 5 years with the final diagnosis of unilateral or bilateral hydronephrosis referred to Besat hospital in Hamadan, between March 2010 and February 2011 were consecutively enrolled. Schwartz and Gentian equations were employed to determine GFR based on plasma creatinine and cystatin C levels, respectively. Results: The proportion of GFR based on Schwartz equation was 70.19± 24.86 ml/min/1.73 m2, while the level of this parameter based on Gentian method and using cystatin C was 86.97 ± 21.57 ml/min/1.73 m2. The Pearson correlation coefficient analysis showed a strong direct association between the two levels of GFR measured by Schwartz equation based on serum creatinine level and Gentian method and using cystatin C (r = 0.594, P < 0.001). The linear association between GFR values measured with the two methods included cystatin C based GFR = 50.8+ 0.515 × Schwartz GFR. The correlation between GFR values measured by using serum creatinine and serum cystatin C measurements remained meaningful even after adjustment for patients’ gender and age (r = 0.724, P < 0.001). Conclusion: The equation developed based on cystatin C level is comparable with another equation, based on serum creatinine (Schwartz formula) to estimate GFR in children.
Highlights
The use of a simple and accurate glomerular filtration rate (GFR) estimating method aiming minute assessment of renal function can be of great clinical importance
Implication for health policy/practice/research/medical education: In this study we aimed to evaluate the benefit of using serum cystatin C based glomerular filtration rate (GFR) calculation instead of creatinine based formula to early prediction of which hydronephrotic children need surgical intervention
With respect to applying different equations for estimating eGFR, the amount of eGFR based on Schwartz equation was 70.19 ± 24.86 ml/min/1.73 m2, while the level of this parameter based on Gentian method and using cystatin C was 86.97 ± 21.57 ml/min/1.73 m2
Summary
The use of a simple and accurate glomerular filtration rate (GFR) estimating method aiming minute assessment of renal function can be of great clinical importance. The Pearson correlation coefficient analysis showed a strong direct association between the two levels of GFR measured by Schwartz equation based on serum creatinine level and Gentian method and using cystatin C (r = 0.594, P < 0.001). A number of techniques have been introduced for accurate measurement of GFR that among them, applying the clearance of an appropriate chemical marker has priority [2]. In this regard, a suitable marker substance which can freely filtered, not be toxic, non-absorbable or secreted in the tubules of the kidney, and cannot not be altered during passage through the kidneys, will be a suitable substance for assessment [3,4].
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