Low Serum Cholesterol Concentration in Adult Patients with Phenylketonuria- One Centre Experience

Abstract

Introduction: Phenyloketonuria is a rare metabolic disorder caused by a deficiency of the phenylalanine (Phe) hydroxylase enzyme. A reduced intake of natural proteins helps optimise plasma Phe concentration. A relationship between high plasma Phe level and the inhibition of cholesterol synthesis was previously observed but the mechanisms are unclear. Low LDL-cholesterol concentrations were observed in children and adolescent PKU patients, but not in adults. This is the first paper to present lipid profile in adult patients with this condition. Methods: Lipid profile was analysed in adult patients with PKU. We examined associations between Phe and four outcomes: total cholesterol, LDL-cholesterol, HDL-cholesterol and triglycerides. Confounding factors (predictors) were taken into account: body mass index (BMI), age and gender. The statistical analysis was performed using multiple linear regression. Results: Among 176 adult patients 91 were females (52%). The mean age was 32 ± 10.7 years. 82 patients (46%) were on strict PKU diet. Mean Phe was 1017 ± 440 μmol/L. Mean total cholesterol was 4.33 ± 0.94 mmol/L, LDL-cholesterol 2.48 ± 0.8 mmol/L, HDL-cholesterol 1.2 ± 0.34 mmol/L, triglycerides 1.6 ± 0.9 mmol/L. There was no correlation between Phe concentration and lipid profile in our cohort of adult patients with PKU. No cardiovascular events were documented in our cohort. Conclusions: In conclusion, the outcomes of the study demonstrate that mean total cholesterol, LDL-cholesterol and triglycerides concentrations were substantially lower as compared to healthy population, which may confer their reduced cardiovascular risk. Lipid profile remained low irrespectively of Phe concentration.