Clearance of branched chain amino acids by peritoneal dialysis in maple syrup urine disease.

Thirty-eight hours of peritoneal dialysis (PD) was used in an 8-day-old, 3.35 kg boy with maple syrup urine disease (MSUD) to enhance the removal of branched chain amino acids (BCAA). PD clearances for leucine, isoleucine, and valine were 3 ml/min/1.73 m2, compared to urinary clearances of 0.16 ml/min/1.73 m2 (0.4 ml/min/1.73 m2 for isoleucine). The augmented clearance was reflected by a faster rate of fall in the plasma leucine level during dialysis (38 microM/hr) than before or immediately after dialysis (10 microM/hr). The biochemical improvement was accompanied by neurologic improvement in the baby. Once the leucine level fell to below 1500 mu + M, the unaugmented rate of fall for leucine (21 microM/hr) was similar to that augmented by PD. Our experience demonstrates that PD is useful for enhancing clearance of BCAA at leucine levels greater than 1500 microM and that it speeds neurologic recovery.