{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,20]],"date-time":"2026-04-20T21:57:48Z","timestamp":1776722268819,"version":"3.51.2"},"reference-count":23,"publisher":"Wiley","issue":"1","license":[{"start":{"date-parts":[[2014,3,18]],"date-time":"2014-03-18T00:00:00Z","timestamp":1395100800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["European J of Haematology"],"published-print":{"date-parts":[[2014,7]]},"abstract":"Abstract<\/jats:title>Background<\/jats:title>Quantitation of von Willebrand factor (VWF<\/jats:styled-content>) in plasma is a central element in assessing von W<\/jats:styled-content>illebrand disease (VWD<\/jats:styled-content>). VWF<\/jats:styled-content> activity is known to vary, which has partly been ascribed to biological and preanalytical variation. However, a possible diurnal expression of VWF<\/jats:styled-content> has not been thoroughly tested.<\/jats:p><\/jats:sec>Objectives<\/jats:title>We examined whether VWF<\/jats:styled-content> antigen and VWF<\/jats:styled-content> activity in plasma display a diurnal profile in healthy young males, and whether such variation is related to changes in release or elimination.<\/jats:p><\/jats:sec>Methods<\/jats:title>Plasma from 20 healthy young males was collected at 9 time\u2010points over 24\u00a0h (15\u00a0h of light and 9\u00a0h of darkness); the plasma concentration of melatonin was used as an internal control to confirm the normal 24\u2010h rhythms of the individual participants.<\/jats:p><\/jats:sec>Results<\/jats:title>The data, analyzed by rhythmometric statistics, revealed a significant variation (P<\/jats:styled-content><\/jats:italic>\u00a0=\u00a00.02) and total amplitude of 22.6% in VWF<\/jats:styled-content> antigen concentrations over the 24\u2010h period. A pronounced variation in VWF<\/jats:styled-content> activity was also observed, although not significant according to the 24\u2010h statistical model. To examine whether the diurnal pattern was related to changes in elimination or secretion, the ratio between (i) coagulation factor VIII and VWF<\/jats:styled-content> and (ii) VWF<\/jats:styled-content> propeptide and VWF<\/jats:styled-content> was determined. Taken together, the data suggest changes in release and not in clearance.<\/jats:p><\/jats:sec>Conclusions<\/jats:title>Diurnal variation in von Willebrand antigen and activity in plasma represents an important aspect of the biological variation. Standardized time\u2010of\u2010day plasma sampling for quantitation of VWF<\/jats:styled-content> in VWD<\/jats:styled-content> patients seems warranted.<\/jats:p><\/jats:sec>","DOI":"10.1111\/ejh.12298","type":"journal-article","created":{"date-parts":[[2014,2,27]],"date-time":"2014-02-27T07:56:41Z","timestamp":1393487801000},"page":"48-53","source":"Crossref","is-referenced-by-count":19,"title":["Diurnal variation of von W<\/scp>illebrand factor in plasma: the B<\/scp>ispebjerg study of diurnal variations"],"prefix":"10.1111","volume":"93","author":[{"given":"Annette","family":"Timm","sequence":"first","affiliation":[{"name":"Department of Clinical Biochemistry Rigshospitalet University of Copenhagen Copenhagen Denmark"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jan","family":"Fahrenkrug","sequence":"additional","affiliation":[{"name":"Department of Clinical Biochemistry Bispebjerg Hospital University of Copenhagen Copenhagen Denmark"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Henrik L.","family":"J\u00f8rgensen","sequence":"additional","affiliation":[{"name":"Department of Clinical Biochemistry Bispebjerg Hospital University of Copenhagen Copenhagen Denmark"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Henriette P.","family":"Sennels","sequence":"additional","affiliation":[{"name":"Department of Clinical Biochemistry Bispebjerg Hospital University of Copenhagen Copenhagen Denmark"},{"name":"Department of Clinical Biochemistry Glostrup Hospital University of Copenhagen Copenhagen Denmark"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jens P.","family":"Goetze","sequence":"additional","affiliation":[{"name":"Department of Clinical Biochemistry Rigshospitalet University of Copenhagen Copenhagen 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