title: The phenylalanine loading test in the differential diagnosis of dystonia.
abstract: Early diagnosis of dopa-responsive dystonia (DRD) and its delineation from other dystonic syndromes is of great relevance because DRD is an eminently treatable condition. The possible relevance of the phenylalanine loading test (Phe-L) in differentiating DRD from primary focal and generalized dystonia was investigated. A marked difference in the phenylalanine/tyrosine ratio between patients with DRD and patients with other types of dystonia was observed. This indicates that Phe-L may be helpful in the differential diagnosis of dystonias.
authors.affiliation: Department of Neurology, Philipps-University Marburg, Germany. o.bandmann@sheffield.ac.uk
authors.forename: O
authors.initials: O
authors.lastname: Bandmann
authors.forename: M
authors.initials: M
authors.lastname: Goertz
authors.forename: J
authors.initials: J
authors.lastname: Zschocke
authors.forename: G
authors.initials: G
authors.lastname: Deuschl
authors.forename: W
authors.initials: W
authors.lastname: Jost
authors.forename: H
authors.initials: H
authors.lastname: Hefter
authors.forename: U
authors.initials: U
authors.lastname: Müller
authors.forename: P
authors.initials: P
authors.lastname: Zöfel
authors.forename: G
authors.initials: G
authors.lastname: Hoffmann
authors.forename: W
authors.initials: W
authors.lastname: Oertel
mesh_terms: D000284:Administration, Oral; D000328:Adult; D003937:Diagnosis, Differential; D004421:Dystonia / Q000175:diagnosis* / Q000188:drug therapy; D005260:Female; D006801:Humans; D007980:Levodopa / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D010649:Phenylalanine / Q000008:administration & dosage / Q000097:blood; D011237:Predictive Value of Tests; D012016:Reference Values; D012680:Sensitivity and Specificity; D013997:Time Factors; D014443:Tyrosine / Q000097:blood
chemical_list: D014443:Tyrosine; D007980:Levodopa; D010649:Phenylalanine