Phenylketonuria (PKU) and Maple syrup urine disease (MSUD), branched-chain ketoaciduria are genetically transmitted metabolic diseases. PKU results in elevated Phenylalanine levels due to deficient activity of the enzyme Phenylalanine hydroxylase. In the MSUD state, elevated levels of leucine (Leu), isoleucine (Ile), valine (Val), and alloiso-leucine can be detected in blood. The increased concentration of the branched-chain amino acids is caused by an inherited deficient activity of the enzyme branched-chain keto-acid decarboxylase. Failure to diagnose and treat these conditions in newborns can result in severe mental retardation (PKU) or even death (MSUD).
Dietary restriction of Val, Leu, and Ile for MSUD newborns must begin immediately once the diagnosis is made or suspected. MSUD patients must be monitored on a regular schedule in conjunction with the dietary therapy because even relatively small changes in the intake of the branched-chain amino acids may produce rather large fluctuations of their concentrations in the plasma. In this respect, MSUD is more difficult to control by dietary means than phenylketonuria (PKU), because each of the branched-chain amino acids has to be individually adjusted and monitored.
The Pickering Laboratories PKU/MSUD post-column system is a rapid, automated method for the quantitative analysis of Met, Leu + Ile, Tyr and Phe from whole blood samples. Betweeninjection time is 13 min while actual time is only 7 min. The Pickering lithium ion-exchange column has a matched set of eluant and regenerant to provide the best possible separation, sensitivity, and reproducibility. The post-column derivatizing reagent is TRIONE Ninhydrin.