The association of plasma level of phenylalanine with inflammatory markers, insulin resistance, and atherosclerotic indexes in patients with phenylketonuria.

Objectives: Patients with phenylketonuria (PKU) are at increasing risk of metabolic disorders and atherosclerosis. This case-control study aimed to compare the values of atherosclerosis risk factors, including insulin resistance (IR), dyslipidemia, mean of platelet volume (MPV), and systemic inflammation in adult PKU patients.

Methods: Fifty patients with PKU were categorized into two groups: well-controlled (WC) (plasma Phe < 600 µmol/L) and poorly controlled (PC) (Phe > 600 µmol/L). Twenty-five age -, gender -, and BMI-matched healthy individuals were enrolled as the control group. Serum insulin, fasting blood sugar (FBS), and lipids were measured. The systemic inflammatory index (SII) and systemic inflammatory response index (SIRI) were calculated using the counts of neutrophils, lymphocytes, monocytes, and platelets.

Results: Both PKU groups had lower serum cholesterol, low-density lipoprotein, and high-density lipoprotein than the healthy subjects (p < 0.001). No significant difference was observed in IR between the PKU patients and the control group. MPV was significantly higher in the patients with PKU compared to the healthy controls. The levels of SII and SIRI were substantially lower in the WC group compared to the healthy control group and the PC group.

Conclusions: All in all, a higher level of dyslipidemia and MPV were observed in patients with PKU compared to healthy individuals. SII and SIRI were significantly lowered in the WC group compared to the PC group and healthy individuals, suggesting the role of adherence to a restricted diet in reducing the risk of systemic inflammation in patients with PKU.