Document Detail

Von Willebrand factor-cleaving protease (ADAMTS-13) activity in thrombotic microangiopathies: diagnostic experience 2001/2002 of a single research laboratory.
MedLine Citation:
PMID:  12923683     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Severe deficiency of von Willebrand factor-cleaving protease (ADAMTS-13) activity (<5% of normal) is specific for classical thrombotic thrombocytopenic purpura (TTP), a disorder presenting with thrombocytopenia, microangiopathic haemolytic anaemia and often with organ dysfunction such as neurological symptoms, renal failure, and fever. A certain, though according to several case series, variable percentage of patients with clinically diagnosed TTP and most patients with other forms of thrombotic icroangiopathies (TMA) do not show severe ADAMTS-13 deficiency.
METHODS: We determined ADAMTS-13 activity in 508 plasma samples of 309 patients referred to our laboratory in 2001 and 2002. Plasma samples with ADAMTS-13 activity <5% were additionally tested for the presence of inhibitory antibodies. Patients were assigned to ten predefined clinical categories according to information provided in the referral letter (TMA not specified; TMA associated with neoplasia or chemotherapy; TMA following haematopoietic stem cell transplantation; TMA with additional disorder; idiopathic TTP; haemolytic-uraemic syndrome (HUS) not specified; HUS with diarrhoea prodrome; atypical HUS; other haematological disorder; no clinical information available).
RESULTS: We detected 50 (16%) patients with severe ADAMTS-13 deficiency. Forty-four (88%) of these patients had been classified as idiopathic TTP, 2 as neoplasia- or chemotherapy-associated, and 4 as non-specified TMA. Among the patients labelled as acute idiopathic TTP, the prevalence of severe ADAMTS-13 deficiency was 63% (44/70). Inhibitory antibodies were found in 31 (62%) patients with ADAMTS-13 activity <5%. Of the 44 patients with acute idiopathic TTP, at initial presentation or at relapse, with ADAMTS-13 activity <5%, 11 were identified to have (probable) constitutional severe ADAMTS-13 deficiency.
CONCLUSION: Severe ADAMTS-13 deficiency is found in about 60% of patients diagnosed with idiopathic TTP but in none of 111 diagnosed with HUS. Plasma ADAMTS-13 activity <5%, however, does not identify all patients clinically diagnosed with TTP. Detection of inhibitory antibodies against ADAMTS-13 helps to differentiate between acquired and constitutional forms of TTP, which may be important for treatment strategies.
J-D Studt; J A Kremer Hovinga; L Alberio; V Bianchi; B Lämmle
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Swiss medical weekly     Volume:  133     ISSN:  1424-7860     ISO Abbreviation:  Swiss Med Wkly     Publication Date:  2003 Jun 
Date Detail:
Created Date:  2003-08-18     Completed Date:  2003-12-04     Revised Date:  2011-02-15    
Medline Journal Info:
Nlm Unique ID:  100970884     Medline TA:  Swiss Med Wkly     Country:  Switzerland    
Other Details:
Languages:  eng     Pagination:  325-32     Citation Subset:  IM    
Central Haematology Laboratory, Inselspital, University of Bern, Bern, Switzerland.
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MeSH Terms
ADAM Proteins
Aged, 80 and over
Metalloendopeptidases / blood*
Middle Aged
Purpura, Thrombotic Thrombocytopenic / diagnosis,  enzymology*
Reg. No./Substance:
EC 3.4.24.-/ADAM Proteins; EC 3.4.24.-/ADAMTS13 protein, human; EC 3.4.24.-/Metalloendopeptidases

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