Phenylketonuria (PKU) belongs to genetically determined types of hyperphenylalaninemia (HPA). Due to all-population screening and possibilities of successful therapy it represents a model example of medical approach to hereditary metabolic disorders. The optimal metabolic compensation enables an adequate mental development without neurological damage. In contrast, insufficient metabolic compensation results in CNS damage. The early childhood is the period of highest health risk. The autohors analyze the occurrence of PKU consequences and their relation to the degree of metabolic compensation in a group of 66 patients from the Center for Long-term Observation of Patients with PKU at Children´s Hospital in Košice. No pathological symptoms were observed in the subgroup with non-PKU HPA. The ideal and medium degree of metabolic compensation was associated with a lower occurrence of PKU consequences. On the other hand, insufficient compensation was associated with a high incidence of pathological manifestations (90 % occurrence of psychopathological and 67% occurrence of neuropathological sings).

        Key words: phenylketonuria, metabolic compensation, CNS damage