Variability of the factor VIII response to DDAVP in a large kindred with mild haemophilia A

Since 1977, desmopressin acetate (DDAVP) has established its important role in the clinical management of bleeding in milder cases of von Willebrand's disease and haemophilia A. We present in vivo DDAVP response data from a large kindred suffering from mild haemophilia A. Levels of

C in 22 affected family members ranged from 0.11 to 0.24 IU mL(-1) of

C (0.18 ± 0.04, mean ± SD), increasing to 0.22-0.92 IU mL(-1) after DDAVP, giving a mean response ratio of 3.5. Response rates by various routes of administration did not differ significantly, being 3.3 for subcutaneous administration (n= 17), 3.7 for intravenous administration (n= 4) and 3.2 for intranasal spray application (n= 1). No significant correlation was found between the pretreatment level and the response rate. In three individuals, the post-DDAVP level of

C was below 0.40 IU mL(-1) , the value we arbitrarily regard as the lower limit of a successful response for haemostatic efficacy suited for self-management purposes, demonstrating that the response rate in a given member of the family cannot be predicted from previous experiences with other haemophilic members of the same subset.