VON-WILLEBRAND-FACTOR IN JUVENILE DERMATOMYOSITIS

Objective. To evaluate whether plasma von Willebrand factor (VWF) levels are a useful indicator of disease activity in juvenile dermatomyositis (DM). Methods. Serum vWF levels were prospectively measured in 15 patients with juvenile DM and were compared to serum muscle enzyme levels, muscle strength, and presence of extramuscular manifestations. Results. 6/15 active disease periods were accompanied by an increase in vWF; 9 were not. Elevated VWF levels did not relate to the presence of active skin disease or calcinosis. vWF was not consistently related to muscle strength, CPK, or aldolase in the study group. Two patients had elevations of VWF in association with viral infections while their DM was quiescent. Conclusion. An elevated vWF level is often indicative of a disease exacerbation in DM, and thus may be helpful in managing difficult cases. However, it is not consistently elevated in, nor specific for active disease in DM. It therefore cannot be recommended as a routine test in patients with DM. When used, results should be interpreted with caution.