Metabolic Diseases with or without Psychomotor Impairment

Abstract

The possibility of congenital enzymatic defects of the lipid, protein, or carbohydrate metabolism has to be considered in patients with progressive psychomotor retardation. The retardation may present as an isolated finding or be associated with unremitting peripheral neurologic disturbances or with hepatosplenomegaly. Even an otherwise unexplained progressive hepatic or splenic enlargement should raise the suspicion of a metabolic disorder. The suspicion increases if the child has blood relatives with metabolic disorders and/or siblings who are retarded or who died at an early age, or if the child failed to feed well or had an undue tendency to vomiting during infancy. After sequelae of birth injuries or of encephalitis have been excluded, screening tests for metabolic disorders should be performed with urine, blood, and CSF (Table 22). If abnormal protein metabolism is suspected, a few rapid urine screening tests (Table 23) can narrow the diagnostic possibilities to a few choices before the necessary amino acid chromatogram is ordered.