Open AccessLarge neutral amino acid status in association with P:T ratio and diet in adult and pediatric patients with phenylketonuria
Author(s) -
Douglas Teresa D.,
Nucci Anita M.,
Berry Ann M.,
Henes Sarah T.,
Singh Rani H.
Publication year - 2019
Publication title -
jimd reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.412
H-Index - 25
ISSN - 2192-8312
DOI - 10.1002/jmd2.12076
Subject(s) - endocrinology , medicine , phenylalanine , valine , plasma concentration , food intake , blood plasma , chemistry , amino acid , biochemistry
Abstract Background Intake of large neutral amino acids (LNAA) may inhibit phenylalanine (PHE) transport across the blood brain barrier and assist with blood PHE control in patients with phenylketonuria (PKU). We evaluated the interrelationship between LNAA in plasma and diet on Phe:Tyr (P:T) ratio in patients with PKU and the influence of dietary factors on plasma LNAA markers. Methods Plasma amino acid values and 3‐day food record analysis from two studies (34 male/30 female; age 4.6‐47 years) were examined. For pediatrics (<18 years) and adults (≥18 years) the relationship between P:T ratio, plasma LNAA, and dietary intake patterns were investigated. Results Dietary factors influencing P:T ratio included intake of total protein (g/kg), medical food (MF) protein (g/kg, % below Rx), and LNAA (g) in the full cohort ( P < .05). Associations were found between plasma valine and other dietary and plasma LNAA in pediatrics ( P < .05) and plasma LNAA with dietary LNAA intake in adults ( P = .019). Plasma P:T ratio was inversely associated with plasma LNAA concentrations in both age groups ( P < .05). Aside from histidine in pediatrics ( P = .024), plasma LNAA did not differ by having plasma PHE levels within or above the therapeutic range (120‐360 μmol/L). Plasma LNAA in both age groups was similar to reported healthy control values. Conclusion P:T ratio is significantly tied to dietary LNAA, adherence to MF Rx, and plasma LNAA concentrations. Additionally, P:T ratio and valine may be effective clinical proxies for determining LNAA metabolic balance and LNAA quality of the diet in patients with PKU.