NLST - Maple Syrup Urine Disease (MSUD)

Maple Syrup Urine Disease

A rare inherited metabolic disorder where the body cannot break down branched-chain amino acids (BCAAs)

Leucine, Isoleucine, Valine

The three specific BCAAs that accumulate toxically in the blood and brain in MSUD

Branched-Chain Alpha-Ketoacid Dehydrogenase (BCKD)

The enzyme complex that is deficient in MSUD

Leucine

The most dangerous amino acid in MSUD because it is highly neurotoxic

Cerebral edema

Brain swelling caused by the toxic accumulation of Leucine

Classic MSUD

The most severe type of MSUD, appearing within the first week of life

Burnt sugar

Besides maple syrup, the urine of an MSUD patient may have this characteristic odor

Newborn screening

The primary diagnostic tool used to detect elevated plasma leucine, valine, and isoleucine

Natural protein

This must be strictly restricted in MSUD because all forms contain BCAAs

BCAA-free amino acid formula

The primary protein source for MSUD patients

100-150 kcal/kg/day

The typical energy requirement for infants with MSUD to prevent catabolism

Catabolism

The breakdown of body protein that must be avoided because it releases dangerous BCAAs

Glucose

During illness, MSUD management requires increasing the intake of this carbohydrate to prevent crisis

Metabolic crisis + Brain damage

The two primary risks associated with MSUD compared to PKU