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 phenylketonuric patients (PKU; n = 61) compared with a group of inborn error of intermediary metabolism patients (IEM; n = 22), a group of hyperphenylalaninemic children (HPA; n = 37), and a control group without dietary restriction (n = 41). Design and methods: Phenylalanine was analyzed by ion exchange chromatography and triglycerides, cholesterol and HDL were determined by standard procedures with the Cobas Integra analyzer. Results: Serum total cholesterol concentrations were significantly lower in PKU patients compared with IEM patients (whose cholesterol daily intake was similar to those of PKU patients), HPA children and the control group. A negative correlation was observed between cholesterol and phenylalanine concentrations in the PKU patients. Conclusions: Our findings support the hypothesis of a relationship between high plasma phenylalanine levels and an inhibition of cholesterogenesis, although the low cholesterol intake of the special diets may also decrease serum cholesterol values.