Neurometabolic testing in developmental delay.

The goal of this study was to examine the usefulness of neurometabolic testing in patients with unexplained developmental delay. We included 118 patients from ages 3 months to 13 years. The evaluation was conducted according to a protocol that called for stepwise investigations with the intention to minimize unnecessary tests. Clinical and neuroradiologic abnormalities were used as guidelines for the type and extent of the neurometabolic work-up. Based on our results, a diagnosis for a neurometabolic disorder was established in 16 patients (13.6%). Findings regarding abnormal metabolites (amino acids, ammonia, lactate, pyruvate, urine organic acids) did not lead to a diagnosis but to further investigations. Abnormalities in lysosomal enzymes, very-long-chain fatty acids, and urine mucopolysaccharides were definitive in establishing a diagnosis. In conclusion, in children with slowly progressing development with no apparent cause, there is a need for guidelines regarding the type of patients who need to be tested and the kind and extent of neurometabolic diagnostic work-up.