title: Acquired von Willebrand syndrome in patients with overt hypothyroidism: a prospective cohort study.
abstract: Numerous case reports have been published on acquired von Willebrand syndrome (aVWS) in patients with hypothyroidism, but no prospective studies have been published. The aim of this study was to investigate laboratory and clinical characteristics of aVWS in patients with newly diagnosed overt hypothyroidism. An observational cohort study was performed between May 2007 and February 2012. Consecutive hypothyroid patients before or within the first 48 h of replacement therapy were enrolled. At inclusion, blood was sampled for coagulation tests and bleeding history was documented by means of a standardized bleeding questionnaire. Repeat samples were obtained after restoration of euthyroidism. The prevalence of aVWS, defined as von Willebrand factor antigen (VWF:Ag) ≤50% and/or VWF ristocetin activity (VWF:RCo) ≤50%, was calculated. Patients with aVWS were subsequently divided into severe (VWF:Ag and/or VWF:RCo ≤10%), moderate (VWF:Ag and/or VWF:RCo between 10 and 30%) or mild (VWF:Ag and/or VWF:RCo between 30 and 50%). A total of 90 patients were included among whom a prevalence of aVWS of 33% was found. There were no patients with severe aVWS. Eight patients (9%) had moderate aVWS and 21 (23%) had mild aVWS. Bleeding score was negatively correlated with both VWF:Ag (β -0.32, P = 0.03) and VWF:RCo (β -0.32, P = 0.02). After restoration of euthyroidism, VWF:Ag had significantly increased by 44%, VWF:RCo by 36%, factor VIII by 39%, and endogenous thrombin potential by 10%. aVWS has a high prevalence in hypothyroid patients. Highest bleeding scores in patients with lower VWF levels suggest clinical relevance.
authors.affiliation: Department of Internal Medicine, Slotervaart Hospital, Amsterdam, The Netherlands; Department of Vascular Medicine, Academic Medical Centre, Amsterdam, The Netherlands.
authors.forename: D J F
authors.initials: DJ
authors.lastname: Stuijver
authors.forename: E
authors.initials: E
authors.lastname: Piantanida
authors.forename: B
authors.initials: B
authors.lastname: van Zaane
authors.forename: L
authors.initials: L
authors.lastname: Galli
authors.forename: E
authors.initials: E
authors.lastname: Romualdi
authors.forename: M L
authors.initials: ML
authors.lastname: Tanda
authors.forename: J C M
authors.initials: JC
authors.lastname: Meijers
authors.forename: H R
authors.initials: HR
authors.lastname: Büller
authors.forename: V E A
authors.initials: VE
authors.lastname: Gerdes
authors.forename: A
authors.initials: A
authors.lastname: Squizzato
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000097:blood / Q000150:complications*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013963:Thyroid Hormones / Q000097:blood; D055815:Young Adult; D014842:von Willebrand Diseases / Q000097:blood / Q000209:etiology*; D014841:von Willebrand Factor / Q000378:metabolism
chemical_list: D013963:Thyroid Hormones; D014841:von Willebrand Factor
keywords: acquired; bleeding; coagulation; hypothyroidism; von Willebrand syndrome