Pharmacokinetic studies with FVIII/von Willebrand factor concentrate can be a diagnostic tool to distinguish between subgroups of patients with acquired von Willebrand syndrome

Acquired von Willebrand syndrome (AVWS) has been associated mainly with mon oclonal gammopathy of uncertain significance (MGUS), clonal lymphoprolifera tive or myeloproliferative disorders: and autoimmunity. In the present work we studied 6 patients with AVWS: four with MGUS IgG (h or K), one with sma ll lymphocytic lymphoma and one with agnogenic myeloid metaplasia (AMM). Al l the patients underwent a pharmacokinetic analysis at presentation in orde r to study potential differences in recovery, clearance (CL) or terminal ha lf-life (THL) following administration of von Willebrand factor (VWF) conce ntrate. In all the patients with AVWS an increase in clearance and a decrea se in THL was observed as compared to these parameters in patients with her editary type 3 von Willebrand disease (VWD). No difference in recovery was observed among the groups. The increase in clearance and the decrease in TH L were significantly more pronounced in the group of MGUS patients (57.93 /- 25.6 ml/h/kg,. and 1.39 +/- 0.5 h, respectively) as compared to these pa rameters in the AMM (8.06 ml/h/kg, and 6.96 h, respectively) or the lymphom a (4.76 ml/h/kg, and 6.76 h, respectively) patients (p = 0.03 for clearance and 0.001 for THL). These data indicate that the pharmacokinetic analysis can be a useful tool to distinguish between MGUS-related and other causes o f AVWS, and to plan an appropriate treatment accordingly.