Creatinine-based equation to estimate the glomerular filtration rate in Japanese children and adolescents with chronic kidney disease

Abstract

Background

Renal inulin clearance is the gold standard for evaluation of kidney function, but cannot be measured easily in children. Therefore, we utilize the serum creatinine (Cr)-based estimated GFR (eGFR) measuring serum Cr by the enzymatic method, and we have reported simple serum Cr-based eGFR in Japanese children aged between 2 and 11 years old. Furthermore, we should use serum Cr-based eGFR in Japanese adolescents as well as children with chronic kidney disease for evaluation of renal function.

Methods

The inulin clearance and serum Cr level determined by an enzymatic method were measured in 131 pediatric chronic kidney disease (CKD) patients between the ages of 2 and 18 years old with no underlying disease affecting renal function except CKD to determine the serum Cr-based eGFR in Japanese children and adolescents.

Results

We offer the complex estimated GFR equation using polynomial formulae for reference serum creatinine levels with body length in Japanese children except infants, resulting in the following equation:

$$ {\text{eGFR}} = 110.2 \times ({\text{reference serum Cr}}/{\text{patient's serum Cr}}) + 2.93 $$

Reference serum Cr levels (y) are shown by the following two equations of body length (x):

$$ \begin{aligned} {\text{Males}}:\quad \, y = & -1.259x^{5} + 7.815x^{4} -18.57x^{3} + 21.39x^{2} -11.71x + 2.628 \\ {\text{Females}}:\quad \, y = & -4.536x^{5} + 27.16x^{4} -63.47x^{3} + 72.43x^{2} -40.06x + 8.778 \\ \end{aligned} $$

Conclusion

The new polynomial eGFR formula showing the relationship with body length and serum Cr level may be applicable for clinical screening of renal function in Japanese children and adolescents aged between 2 and 18 years.