Is there a relationship between plasma phenylalanine and cholesterol in phenylketonuric patients under dietary treatment?

Objectives: To study the lipid profile in a group of treated phenylketonuri c patients (PKU; n = 61) compared with a group of inborn error of intermedi ary metabolism patients (IEM; n = 22), a group of hyperphenylalaninemic chi ldren (HPA; n = 37), and a control group without dietary restriction (n = 4 1). Design and methods: Phenylalanine was analyzed by ion exchange chromatograp hy and triglycerides, cholesterol and HDL were determined by standard proce dures with the Cobas Integra analyzer. Results: Serum total cholesterol concentrations were significantly lower in PKU patients compared with IEM patients (whose cholesterol daily intake wa s similar to those of PKU patients), HPA children and the control group. A negative correlation was observed between cholesterol and phenylalanine con centrations in the PKU patients. Conclusions: Our findings support the hypothesis of a relationship between high plasma phenylalanine levels and an inhibition of cholesterogenesis, al though the low cholesterol intake of the special diets may also decrease se rum cholesterol values. (C) 2001 The Canadian Society of Clinical Chemists. All rights reserved.