title: Serum phenylalanine in patients post trauma and with sepsis correlate to neopterin concentrations.
abstract: 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 (r (s) = 0.375, p < 0.001). No such association existed between neopterin and tyrosine concentrations (r (s) = -0.018), but neopterin concentrations correlated to the phenylalanine to tyrosine ratio (r (s) = 0.328, p = 0.001). Increased phenylalanine implies insufficient conversion by phenylalanine (4)-hydroxylase (PAH). Oxidative stress due to immune activation and inflammation may destroy cofactor 5,6,7,8-tetrahydrobiopterin and impair PAH activity. This assumption is further supported by the correlation found between higher neopterin concentrations and higher phenylalanine to tyrosine ratio, which estimates efficacy of PAH.
authors.affiliation: Department of Surgery, Medical University of Vienna, Vienna, Austria.
authors.forename: M
authors.initials: M
authors.lastname: Ploder
authors.forename: G
authors.initials: G
authors.lastname: Neurauter
authors.forename: A
authors.initials: A
authors.lastname: Spittler
authors.forename: K
authors.initials: K
authors.lastname: Schroecksnadel
authors.forename: E
authors.initials: E
authors.lastname: Roth
authors.forename: D
authors.initials: D
authors.lastname: Fuchs
mesh_terms: D000328:Adult; D000368:Aged; D001708:Biopterins / Q000031:analogs & derivatives / Q000378:metabolism; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D015394:Molecular Structure; D019798:Neopterin / Q000097:blood*; D018384:Oxidative Stress / Q000276:immunology; D010649:Phenylalanine / Q000097:blood* / Q000737:chemistry / Q000378:metabolism; D010651:Phenylalanine Hydroxylase / Q000737:chemistry / Q000378:metabolism; D015203:Reproducibility of Results; D018805:Sepsis / Q000097:blood*; D014443:Tyrosine / Q000096:biosynthesis; D014947:Wounds and Injuries / Q000097:blood*
chemical_list: D001708:Biopterins; D014443:Tyrosine; D010649:Phenylalanine; D019798:Neopterin; D010651:Phenylalanine Hydroxylase; C003402:sapropterin