Which laboratory tests are important for diagnosing von Willebrand's disease?

The key tests for diagnosing von Willebrand's disease include activated partial thromboplastin time (aPTT), prothrombin time (PT), and factor VIII:C activity.

aPTT is particularly significant because von Willebrand's disease often correlates with prolonged aPTT due to the involvement of factor VIII, which is stabilized by von Willebrand factor. In individuals with von Willebrand's disease, the levels of factor VIII activity may be reduced, which is crucial for effective blood clotting.

Using PT also provides context for differentiating between various coagulopathies, even though as a primary test it is usually normal in von Willebrand's disease. The status of factor VIII:C activity is directly linked to the function of von Willebrand factor in the coagulation cascade, and abnormal levels often point toward von Willebrand's disease.

The other tests mentioned do not provide relevant information for diagnosing this specific condition. A complete blood count and blood culture are not specific to assessing von Willebrand's disease; they will not indicate the disorder. Electrolytes and liver function tests also do not provide insight into the coagulation factors associated with von Willebrand's disease. A platelet function assay is useful but is insufficient on its own to diagnose