Serum phenylalanine in patients post trauma and with sepsis correlate to neopterin concentrations

Increased blood concentrations of phenylalanine in patients with trauma and sepsis are common but unexplained. We examined the potential relationship between serum concentrations of phenylalanine and the immune activation marker neopterin in 84 specimens of 18 patients (14 males and 4 females) post-trauma during 12–14 days of follow up. Compared to healthy controls, average phenylalanine and neopterin concentrations were elevated in patients, and there existed a positive correlation between concentrations of the two analytes (rs = 0.375, p < 0.001). No such association existed between neopterin and tyrosine concentrations (rs = −0.018), but neopterin concentrations correlated to the phenylalanine to tyrosine ratio (rs = 0.328, p = 0.001).