A 67 year old male with IgA myeloma has been investigated for a severe deficiency of plasma vWf/F. VIII but normal platelet vWf/F. VIII. He has no personal history nor family history of bleeding problems. He was initially investigated for a prolonged APTT of 43 secs. (25-40) obtained in a preoperative clotting screen. During this investigation he was found to have IgA myeloma. In retrospect, an APTT prior to uneventful coronary artery bypass surgery two years previously had been prolonged.

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... ne investigation has shown that platelet count and bleeding time have been repeatedly normal. Plasma F. VIII:C is 0.08 u/ml., F. VIII:Cag 0.07 u/ml., vWf:Ag 0.05 u/ml. and ristocetin cofactor 0.05 u/ml. In contrast, platelet values for vWf:Ag of 53 units/109 platelets and F. VIII:Cag of 176 units/109 platelets are within the normal ranges for our laboratory. The platelet lysate vWf multimer pattern is also normal. Patient's plasma shows inhibitory activity against vWf:Ag but not against either F. VIII:C or ristocetin cofactor activity. When patient plasma is incubated for 60 mins at 37°C with vWf and analysed by crossed Immunoelectrophoresis (CIE) for vWf:Ag, a double arc precipitin line is observed with marked retardation of the first arc. A similar vWf:Ag CIE double precipitin arc is seen following the infusion of cryoprecipitate. T 1/2 for F. VIII:C and vWf:Ag are both reduced following the infusion of cryoprecipitate - F. VIII:C 2 hrs, vWf:Ag 3 trs. No secondary rise in F. VIIIrC is seen at 24 hrs. Despite severe deficiency of plasma vWf/F. VIII, this man does not have a clinical bleeding tendency. We postulate that his plasma vWf/F. VIII deficiency is the result of complexing of his IgA myeloma protein with vWf, resulting in premature clearance of the vWf/F. VIII complex. This case further emphasizes the role of platelet associated coagulation factors in maintaining normal haemostasis.