Maple Syrup Urine Disease (MSUD) is due to an inability to metabolize branched chain amino acids. Classic MSUD presents within a few days of delivery.

Classic MSUD is associated with no or very low activity of the BCKAD complex (branched-chain alpha-ketoacid dehydrogenase complex).


General findings:

(1) poor feeding

(2) tachypnea

(3) maple syrup smell to urine and cerumen due to the presence of sotolone (4,5-dimethyl-3-hydroxy-2[5h]-furanone)


Abnormal muscle tone:

(1) alternating muscle tone (hypertonia and hypotonia)

(2) opisthotonus



(1) intermittent apnea progressing to central respiratory failure

(2) seizures

(3) irritability

(4) lethargy progressing to coma

(5) stereotypic movements (bicycling, fencing)


Laboratory findings:

(1) ketonuria

To read more or access our algorithms and calculators, please log in or register.