Exchange transfusion in acute episodes of maple syrup urine disease. Studies on branched-chain amino and keto acids.

Two neonates with maple syrup urine disease were treated by exchange transfusion. Within 15 h blood leucine and KICA concentrations were lowered from 2.6 mM to 1.1 mM using 570 to 620 ml blood per kg body weight. The other branched-chain amino acid/keto acid pairs fell to normal. During exchange transfusion the patient's nitrogen balance seems to be negative. Further exchange transfusion was useless. More importantly the patient should be forced into an anabolic state by high caloric supply or insulin plus glucose treatment. More KICA than leucine was eliminated, however, KICA blood levels remained slightly higher than that of leucine indicating different leucine/KICA equilibria in extravascular compartments than in blood. In a given time interval exchange transfusion was more effective than peritoneal dialysis, probably due to a lack of an additional (peritoneal) membrane. Renal excretion of branched-chain amino and keto acids was very inefficient. The allegedly most toxic metabolite, KICA, had the lowest renal clearance of the branched-chain keto acids.