title: Laboratory diagnosis of von Willebrand disorder. Current practice in the southern hemisphere.
abstract: A survey of 44 laboratories was conducted to evaluate current testing proficiency in the diagnosis of von Willebrand disorder (vWD) and to assess recent changes in test practices. Laboratories performed their usual panel of tests for vWD and interpreted results for the likelihood of vWD and potential subtype. Samples were as follows: normal plasma; borderline normal or abnormal levels of von Willebrand factor (vWF) and factor VIII; type 3 vWD; type 2A vWD; and 2 samples from a healthy person, processed after handling at 22 degrees C and 4 degrees C, respectively. Interassay and within-method coefficients of variation were similar for all assays (approximately 15%-25%). Most laboratories reported test values consistent with expected findings and made correct interpretations, although discrepant results for 5% to 10% of responses are of concern. For the sample stored at 4 degrees C, all laboratories detected low or borderline levels of vWF and factor VIII coagulant, and no laboratory identified this sample as from a healthy person. In contrast, for the sample stored at 22 degrees C, most laboratories reported normal results. Compared with previous results, performance of some assays has declined while that of others has increased. Laboratories generally are proficient in tests for vWD, and transport of samples at 4 degrees C before processing may lead to false identification of vWD, suggesting that NCCLS guidelines should be reviewed.
authors.affiliation: Department of Haematology, RCPA Quality Assurance Program, Institute of Clinical Pathology and Medical Research, Westmead Hospital, Westmead, Australia.
authors.forename: Emmanuel J
authors.initials: EJ
authors.lastname: Favaloro
authors.forename: Roslyn
authors.initials: R
authors.lastname: Bonar
authors.forename: John
authors.initials: J
authors.lastname: Sioufi
authors.forename: Mark
authors.initials: M
authors.lastname: Hertzberg
authors.forename: Alison
authors.initials: A
authors.lastname: Street
authors.forename: John
authors.initials: J
authors.lastname: Lloyd
authors.forename: Katherine
authors.initials: K
authors.lastname: Marsden
mesh_terms: D000941:Antigens / Q000097:blood; D019411:Clinical Laboratory Techniques / Q000592:standards*; D003094:Collagen / Q000378:metabolism; D003937:Diagnosis, Differential; D004797:Enzyme-Linked Immunosorbent Assay; D005169:Factor VIII / Q000032:analysis; D005189:False Positive Reactions; D006801:Humans; D007118:Immunoassay; D007840:Latex; D046911:Macromolecular Substances; D011786:Quality Control; D015203:Reproducibility of Results; D014842:von Willebrand Diseases / Q000145:classification / Q000175:diagnosis*; D014841:von Willebrand Factor / Q000032:analysis / Q000378:metabolism
chemical_list: D000941:Antigens; D007840:Latex; D046911:Macromolecular Substances; C029417:Von Willebrand antigen; D014841:von Willebrand Factor; D005169:Factor VIII; D003094:Collagen