[Clearance, reabsorption and excretion of free and bound L-carnitine in children].

Acylcarnitines are by-products of fatty acid, pyruvate and some xenobiotics metabolism excreted in urine. We compare the renal handling of free and acylcarnitine in a group of 15 healthy children in relation to sodium and urea excretion and to sodium fractional tubular reabsorption (FTR%) and fractional excretion (FE%). Urea and sodium were determined by routine laboratory method; free and acylcarnitines by enzymatic one. FTR% and FE% were determined as a % of filtration load. Linear regression was used for calculation of correlation coefficient "r" from paired data. Low correlation (r = 0.25; p = 0.42) between urea and free carnitine excretion was observed; for excretion of acylcarnitine and urea correlation was much higher (r = 0.61; p < 0.03). Excretion of free correlation was negatively correlated with sodium FTR (r = -0.86; p < 0.001) and there was no correlation at all for acylcarnitine excretion and sodium FTR. It can be assumed:-neither excretion nor reabsorption of acylcarnitines are Na-dependent;-renal handling of free and total carnitines proceeds on different mechanisms.