ABNORMAL 3,4-DIHYDROXYPHENYLALANINE (DOPA) CONCENTRATIONS IN PLASMA AND URINE OF PATIENTS WITH CYSTIC-FIBROSIS

Abstract. Plasma and urine concentrations of the free amino acid 3,4‐dihydroxyphenylalanine (dopa) were determined in a blind study in 16 children and adolescents with cystic fibrosis (CF), eight heterozy‐gote parents of these children and in 11 healthy subjects who served as controls. To exclude any drug interference with catecholamine metabolism and to evaluate a tentative basic metabolic alteration in cystic fibrosis, the same determinations were done in 11 newly diagnosed infants (age 1–84 months). Free plasma dopa was significantly (P<0.01) elevated in CF (27.0 ± 6.1 nmol l‐1 vs. 19.1 ±5.0 nmol l‐1 in the controls); heterozygotes had the lowest concentration: 11.5 ± 5.8 nmol 1 (P<0.01 compared with normals). Increased plasma dopa concentrations were measured in the newly diagnosed infants (35.4± 16.9 nmol l‐1). Renal dopa clearance was the same in cystic fibrosis (9.26 ± 5.71 ml min‐1 1.73 m‐2) and controls (10.87 ± 2.46 ml min‐1 1.73 m‐2). A concommitant elevation of metabolic products as dopamine and noradrenaline in plasma and urine was noticed. These data are consistent with a dopa abnormality in this genetic disease. Copyright © 1990, Wiley Blackwell. All rights reserved