title: New formulas for mixing test to discriminate between lupus anticoagulant and acquired hemophilia A.
abstract: BACKGROUND
  Lupus anticoagulant (LA) is an antibody that interferes with in vitro coagulation reactions. The mixing test is considered useful for LA diagnosis and is also recommended to differentiate between acquired hemophilia A (AHA) and factor deficiency. However, there has been little study to differentiate between LA and AHA. Our aims are to investigate whether we can differentiate LA and AHA by the mixing test and to establish new formulas for the mixing test to differentiate these samples clearly.
  
  
  METHODS
  We examined 27 LA-positive, 29 coagulation factor deficient, 24 unfractionated heparin and 48 AHA samples. Index of circulating anticoagulant (ICA) values, calculated from the clotting times without incubation and after 2h incubation, were defined as ICA immediate (ICAi) and ICA delayed (ICAd) respectively. ICAd/ICAi and ICAd-ICAi were also calculated to compare the sensitivity and specificity.
  
  
  RESULTS
  ICAd/ICAi and ICAd-ICAi for AHA samples were significantly higher than those of the other sample groups. The sensitivities to AHA in ICAi, ICAd, ICAd/ICAi and ICAd-ICAi were 66.7%, 81.3%, 93.8% and 91.7% respectively, while the specificities for AHA were 45.0%, 66.3%, 85.0% and 98.8% respectively. ICAd/ICAi and ICAd-ICAi showed high sensitivity and specificity.
  
  
  CONCLUSIONS
  ICAd/ICAi and ICAd-ICAi were useful for LA and AHA diagnosis, because these could differentiate between LA and AHA samples. These new formulas can contribute to the rapid diagnosis and treatment of LA and AHA.
authors.affiliation: Department of Internal Medicine, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido, Japan; Hemostasis Product Engineering, Sysmex Corporation, Kobe, Hyogo, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Kumano
authors.affiliation: Department of Internal Medicine, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido, Japan. Electronic address: iekom@hoku-iryo-u.ac.jp.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Ieko
authors.affiliation: Department of Clinical Laboratory, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido, Japan.
authors.forename: Sumiyoshi
authors.initials: S
authors.lastname: Naito
authors.affiliation: Department of Clinical Laboratory, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido, Japan.
authors.forename: Mika
authors.initials: M
authors.lastname: Yoshida
authors.affiliation: Department of Internal Medicine, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido, Japan.
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Takahashi
authors.affiliation: Department of Internal Medicine, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido, Japan; Hemostasis Product Engineering, Sysmex Corporation, Kobe, Hyogo, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Suzuki
authors.affiliation: Hemostasis Product Engineering, Sysmex Corporation, Kobe, Hyogo, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Komiyama
mesh_terms: D000925:Anticoagulants / Q000097:blood; D016736:Antiphospholipid Syndrome / Q000097:blood / Q000175:diagnosis*; D006467:Hemophilia A / Q000097:blood / Q000175:diagnosis*; D006493:Heparin / Q000097:blood; D006801:Humans; D016682:Lupus Coagulation Inhibitor / Q000097:blood*; D010314:Partial Thromboplastin Time / Q000379:methods*
chemical_list: D000925:Anticoagulants; D016682:Lupus Coagulation Inhibitor; D006493:Heparin
keywords: Antiphospholipid syndrome; Diagnosis; Factor 8 deficiency acquired; Lupus coagulation inhibitor; Partial thromboplastin time