What is the recommended management for a patient with suspected Von Willebrand disease and easy bruising?

Management of Easy Bruising with Elevated Ristocetin Cofactor

This patient does not have von Willebrand disease and requires no specific hemostatic treatment for the elevated ristocetin cofactor, as the laboratory findings show normal Factor VIII activity, normal VWF antigen, and normal aPTT, with only an isolated elevation in ristocetin cofactor that likely represents laboratory variability or acute phase reactant elevation. 1, 2

Laboratory Interpretation

The von Willebrand panel reveals findings inconsistent with VWD:

• Factor VIII activity is normal at 123% (reference range 50-180%), which argues strongly against VWD since VWF carries and stabilizes Factor VIII in circulation, and VWF deficiency leads to secondary Factor VIII reduction 1, 2

• VWF antigen is normal at 165% (reference range 50-217%), indicating adequate quantitative VWF levels 1

• Ristocetin cofactor is elevated at 251% (reference range 42-200%), which is paradoxically high rather than low 1

• aPTT is normal at 27 seconds (reference range 23-32 seconds), further excluding intrinsic pathway defects typical of VWD 1, 2

Understanding the Elevated Ristocetin Cofactor

The isolated elevation of ristocetin cofactor without corresponding decreases in VWF antigen or Factor VIII is not consistent with any type of VWD. 1 Key considerations include:

• VWF is an acute phase reactant, and its levels can vary in response to clinical status, resulting in falsely elevated results 1
• The ratio of VWF:RCo to VWF:Ag is approximately 1.5, which is above the normal range (0.5-0.7 would suggest qualitative VWF defects) 1
• Testing must sometimes be repeated up to 3 times to ensure reliable results due to high coefficients of variation (10-30%) in VWF:RCo assays 1

Differential Diagnosis for Easy Bruising

Since VWD is excluded, alternative causes should be investigated:

• Platelet function disorders: Consider platelet aggregation testing if easy bruising persists, as this can occur independently of VWF abnormalities 1

• Acquired conditions: Stress, inflammation, pregnancy, or estrogen/oral contraceptive use can elevate VWF levels 1

• Blood group O individuals have VWF levels 25% lower than other ABO blood groups, but this patient's levels are elevated 1

• Anatomic or pathological conditions predisposing to bleeding should be evaluated 1

Recommended Management Approach

No hemostatic treatment is indicated based on these laboratory results. 1, 2 The management strategy should include:

1. Repeat VWF testing if clinical suspicion remains high, as VWF levels can fluctuate and testing should be performed when the patient is not acutely ill or stressed 1

2. Obtain complete blood count (CBC) and platelet count to evaluate for thrombocytopenia or thrombocytosis that might explain bruising 1

3. Consider platelet function studies if bruising is clinically significant and other testing is unrevealing 1

4. Evaluate for non-hematologic causes including nutritional deficiencies (vitamin C, vitamin K), connective tissue disorders (Ehlers-Danlos syndrome), or liver disease 1

Important Caveats

• Do not initiate desmopressin or VWF concentrate therapy based on these results, as they are indicated only for documented VWD with VWF activity <30 IU/dL or demonstrated bleeding requiring hemostatic support 2, 3, 4, 5

• Avoid over-medicalization in patients with normal or elevated VWF levels, as the risk of unnecessary treatment outweighs benefits 4, 6

• If surgery is planned, no specific hemostatic prophylaxis is required based on these laboratory values, though standard preoperative bleeding risk assessment should be performed 1