Karol Fishler

The effects of diet discontinuation in children with phenylketonuria.

Discontinuation of the Phe-restricted diet for children treated for PKU has been a controversial issue ever since Homer et al. [3] first introduced the concept in 1962. A recent report by Waisbren et al. [9] assessed this problem in a review of 19 studies of diet discontinuation. Nine reported significant drops in IQ over time and 10 did not. None were well-controlled longitudinal prospective studies. Data reported from the National Collaborative Study by Koch et al. [4] in 1982 and by Williamson et al. [12] in 1985 suggested that IQ changes were occurring in children taken off diet at age 6 years in a randomized trial which, however, was faulted by parental consent. There were 134 children in the study. Sixty-five were randomized to continue on diet and 69 to discontinue dietary therapy; however, only 78% accepted continuation and 75% discontinuation. Holtzman, utilizing a different approach in a review of the same data, concluded that diet restriction should continue after the age of 8 years [2]. Despite these findings, varying policies with regard to diet discontinuation exist in the United States as well as in most other countries [7]. It is likely that the issue will not be easily resolved. Recently, data on 12year-olds from the Collaborative Study was analyzed and it is the purpose of this report to once more assess this important issue.

An approach to management of phenylketonuria

Data are reported on 126 cases of classical phenylketonuria and 14 children with persistent mild hyperphenylalaninemia. An approach to differential diagnosis of children with hyperphenylalaninemia is presented. The method of treatment utilized at the Childrens Hospital of Los Angeles is described. Best results were obtained with early diagnosis and excellent dietary control. While pointed criticism has been leveled at the mandated screening programs for detection of PKU during the newborn period, the data presented in this report substantiate the need for these programs.

Mental retardation in early childhood. A study of 143 infants.

Almost 20 per cent of 143 children referred to a mental retardation project were found not to be mentally retarded. About 5 per cent had preventable forms of mental retardation resulting from conditions such as hypothyroidism, phenylketonuria and galactosemia.Continued sympathetic care by the physician is mandatory. Except in forms of mental retardation known to be hereditary, such as Tay-Sachs disease, one may advise parents that the chance is quite small (about 3 per cent) that more mentally retarded children will be born to them.

Treatment Outcome of Maternal Phenylketonuria

Our experience to date with 40 pregnancies in 13 women with hyperphenylalaninemia indicates that to prevent mental retardation in their children, maternal phenylalanine levels of 120–600 umol/L are needed, in addition to a newborn screening program. While treatment results to date are preliminary, it appears that the phenylalanine‐restricted diet is of value and should be instituted as soon as pregnancy is planned by phenylketonuric women. There is much to be learned by study of these women and referral to a collaborating center in the National Maternal PKU Collaborative Study is recommended.