title: The utility of ADAMTS13 in differentiating TTP from other acute thrombotic microangiopathies: results from the UK TTP Registry.
abstract: Thrombotic microangiopathies (TMAs) are frequently difficult to differentiate clinically, and measurement of ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) remains vital in thrombotic thrombocytopenic purpura (TTP) diagnosis. We retrospectively reviewed cases referred for ADAMTS13 testing, using UK TTP Registry screening data. Of a total 810 cases, 350 were confirmed as TTP. The 460 non-TTP cases comprised secondary TMAs (24·57%) and haemolytic uraemic syndrome (HUS) (27·17% aHUS, 2·83% Shiga-like toxin-producing E. coli [STEC]-HUS); the remainder were TMAs with no clear association, not TMAs, or had no confirmed diagnosis. ADAMTS13 levels were significantly lower in TTP than STEC-HUS, aHUS and other TMAs. TTP patients had significantly lower platelet count (15 × 10(9) /l; range 0-96) than aHUS (57 × 10(9) /l; range 13-145, P < 0·0001) or STEC-HUS (35 × 10(9) /l; range 14-106, P < 0·0001); they also had lower creatinine levels (92 μmol/l; range 43-374) than aHUS (255 μmol/l; range 23-941, P < 0·0001) and STEC-HUS (324 μmol/l; range 117-639, P < 0·0001). However, 12/34 (35·3%) aHUS patients had a platelet count <30 × 10(9) /l and 26/150 (17·3%) of TTP patients had a platelet count >30 × 10(9) /l; 23/150 (15·3%) of TTP patients had a creatinine level >150 μmol/l. This study highlights the wide variety of TMA presentations, and confirms the utility of ADAMTS13 testing in TTP diagnosis.
authors.affiliation: Department of Nephrology, The Royal London Hospital, London, UK.
authors.forename: Sevda
authors.initials: S
authors.lastname: Hassan
authors.affiliation: Department of Haematology, University College London Hospital, London, UK.
authors.forename: John-Paul
authors.initials: JP
authors.lastname: Westwood
authors.affiliation: Department of Haematology, University College London Hospital, London, UK.
authors.forename: Debra
authors.initials: D
authors.lastname: Ellis
authors.affiliation: UCL Centre for Nephrology, Royal Free Hospital, London, UK.
authors.forename: Chris
authors.initials: C
authors.lastname: Laing
authors.affiliation: Department of Haematology, University College London Hospital, London, UK.
authors.forename: Siobhan
authors.initials: S
authors.lastname: Mc Guckin
authors.affiliation: NHSBT Therapeutic Apheresis Services (TAS) and Oxford University Hospitals Trust, Oxford, UK.
authors.forename: Sylvia
authors.initials: S
authors.lastname: Benjamin
authors.affiliation: Department of Haematology, University College London Hospital, London, UK.
authors.forename: Marie
authors.initials: M
authors.lastname: Scully
mesh_terms: D051722:ADAM Proteins / Q000378:metabolism*; D000071120:ADAMTS13 Protein; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D003404:Creatinine / Q000378:metabolism; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D010976:Platelet Count; D011697:Purpura, Thrombotic Thrombocytopenic / Q000175:diagnosis; D012042:Registries; D012189:Retrospective Studies; D057049:Thrombotic Microangiopathies / Q000175:diagnosis*; D055815:Young Adult
chemical_list: D015415:Biomarkers; D003404:Creatinine; D051722:ADAM Proteins; D000071120:ADAMTS13 Protein; C099604:ADAMTS13 protein, human
keywords: ADAMTS13; haemolytic uraemic syndrome; thrombotic microangiopathies; thrombotic thrombocytopenic purpura