Determinants of age-induced VWF level normalization in low VWF and type 1 VWD. Normalization of plasma VWF levels (defined as increase of VWF:Ag, VWF:Act, VWF:CB and FVIII:C >50 IU/dL with aging) was assessed in LoVIC and WiN patients with more than 5 years of retrospective follow-up. Kaplan-Meier curves were used to illustrate determinants of normalization of VWF levels with aging. P values are outcomes of log-rank tests. (A) Normalization in plasma VWF levels during follow-up was significantly higher in LoVIC than in WiN patients. (B) Normalization in plasma VWF levels during follow-up was significantly increased in patients with low VWF and type 1 VWD who demonstrated complete desmopressin responses (defined according to the 2021 ASH/ISTH/WFH/NHF guideline). (C) Age-induced normalization in plasma VWF levels was significantly higher in patients with low VWF and type 1 VWD who did not have a pathological VWF sequence variant. (D) Normalization in plasma VWF levels with aging was markedly reduced in patients with historically lowest levels VWF levels <10 IU/dL. (E) Age-induced normalization in plasma VWF levels was significantly decreased in patients with marked underlying pathophysiological defects (defined as FVIII:C/VWF:Ag ratio ≥1.9 and/or VWFpp/VWF:Ag ratio ≥2.2).