Neonatal screening for metabolic and endocrine diseases.

The screening of neonates for metabolic diseases is important in order to identify a population with or at risk for metabolic diseases. Early diagnosis can then be made, treatment instituted and physical and/or mental handicaps due to the disease can be prevented. The World Health Organization's screening criteria are helpful in selecting those diseases appropriate for screening. Usually a state-designated central laboratory performs the screening tests. All states screen for phenylketonuria (PKU) and hypothyroidism; in addition, 26 states screen for galactosemia, 20 for maple syrup urine disease and 19 for homocystinuria. The cost-benefit ratio for screening programs is excellent, varying from 1:13 to 1:20. The necessary follow-up of patients for diagnosis and treatment can be enhanced by maintaining a close liaison with the laboratory and providing adequate information to parents. As a result of instituting a screening program, the incidence of mental retardation due to PKU has been practically eliminated and new insights about metabolic diseases have been obtained. The rapid progress in technology may soon result in better and cheaper tests capable of identifying more diseases amenable to treatment.