[Hypophenylalaninemia in dietary treatment of phenylketonuria (author's transl)].

One case of hypophenylalaninemia during the dietary low phenylalanine treatment is presented. The general problem of dietary treatment from early ages is reviewed. The appearance of this iatrogenic disease despite adequate supply of this essential aminoacid is stressed. Authors recommend follow-up of these patients in a regional reference center with adecuate technology.