title: Evaluation of three automated chromogenic FVIII kits for the diagnosis of mild discrepant haemophilia A.
abstract: In some mild haemophilia A patients (discrepant phenotype), coagulation FVIII levels by one-stage assay (FVIII-1st) are more than double those by classical two-stage coagulation assay (FVIII-2st), and may fall within the normal range. Our aim was to assess automated two-stage chromogenic FVIII assays (FVIII-chr) for diagnosis of mild discrepant haemophilia A. Three chromogenic FVIII kits (Biophen, Coamatic and Dade-Behring) were evaluated, using recommended and extended incubation times. Samples were tested from patients with discrepant haemophilia (n = 7) and equivalent mild haemophilia (agreement between FVIII-1st and FVIII-2st, n = 4). For equivalent haemophilia, FVIII-chr were consistent with FVIII-1st and FVIII-2st for all kits at all incubation times. For discrepant haemophilia, using recommended incubation times, mean FVIII-chr using Biophen reagents was 22 IU/dl (range 13-31), with Coamatic 26 (17-34) and with Dade-Behring 41 (33-47), compared with 36 (27-44) for FVIII-1st and 8 (6-9) for FVIII-2st. FVIII-chr decreased as incubation time was increased with Biophen and Coamatic, but decreased less with Dade-Behring. FVIII-chr using the Dade-Behring kit gave similar results to FVIII-1st and is not suitable for diagnosis of mild discrepant haemophilia A. FVIII-chr by Biophen and Coamatic kits is suitable for diagnosis of these patients, especially with an extended incubation time.
authors.affiliation: Haematology Division, Institute of Medical and Veterinary Science, Adelaide, SA, Australia. susan.rodgers@imvs.sa.gov.au
authors.forename: S E
authors.initials: SE
authors.lastname: Rodgers
authors.forename: E M
authors.initials: EM
authors.lastname: Duncan
authors.forename: M
authors.initials: M
authors.lastname: Sobieraj-Teague
authors.forename: J V
authors.initials: JV
authors.lastname: Lloyd
mesh_terms: D001777:Blood Coagulation / Q000502:physiology; D005169:Factor VIII / Q000032:analysis* / Q000235:genetics; D006467:Hemophilia A / Q000097:blood / Q000175:diagnosis*; D006801:Humans; D009154:Mutation / Q000235:genetics; D011933:Reagent Kits, Diagnostic
chemical_list: D011933:Reagent Kits, Diagnostic; D005169:Factor VIII