Peri-operative DDAVP Use Leading to Severe Hyponatremia after Total Shoulder Replacement in a Patient with von Willebrand's Disease:

The estimated prevalence of von Willebrand’s disease (vWD) worldwide has been widely reported as near 1%. This makes vWD the most common inherited bleeding disorder. Although the condition can present with varying degrees of severity, it is usually mild and its presence often goes undiagnosed until significant hemorrhagic stress is placed on the patient, such as during major orthopedic surgical procedures. Given the heightened prevalence of the disorder in the general population, it is very important for all surgeons to be aware of its presentation, treatment options, and the side effects of these treatments in order to effectively reduce hemorrhagic and other medical complications related to vWD. von Willebrand’s disease is categorized as a disorder of primary hemostasis involving platelet dysfunction and the inability to produce sufficient plasma concentrations of von Willebrand factor (vWF). It is also associated with qualitative deficits in the structure of vWF which prevents normal function during the clotting cascade. Normal levels and structure of vWF act not only to initiate primary hemostasis but also to stabilize factor VIII. In more clinically significant cases of vWD, recombinant factor VIII protein may be needed in addition to replacement vWF to address all deficiencies in both primary and secondary hemostases [3]. There are three major pharmacologic treatment modalities available to address the clinically significant bleeding risks of vWD. They include the following: vWF/factor VIII replacement (Humate-P*), DDAVP (desmopressin), and antifibrinolytic treatment using estrogen-progesterone hormone therapy [4]. All therapies are associated with their own benefits and possible side effects. DDAVP carries no risk of transmitting infection or immunologic complications, is relatively inexpensive, and should be the preferred prophylactic treatment when possible. The drug acts by increasing endogenous release of vWF from circulating platelets. This maximizes all available circulatory system vWF into the plasma. One of the most significant potential side effects of desmopressin is severe water intoxication and concomitant hyponatremia. This unwanted effect may trigger severe physiologic consequences including seizure and death [6]. The drug acts as a synthetic form of anti-diuretic hormone (ADH), increasing the number of aquaporin channels in the collecting duct of the renal nephron, resulting in heightened free-water absorption, decreased urine output, and potential serum electrolyte dilution. This can become especially true if a patient’s fluid intake is not carefully observed. Excess free-water ingestion should be limited while on DDAVP, and IV fluid use meticulously scrutinized to ensure serum electrolyte concentrations remain at physiologic levels. If IV fluids are necessary, normal saline is preferred over lactated ringers due to its higher concentration of sodium per unit volume which should decrease the potential for DDAVP-induced hyponatremia. Despite the increased susceptibility and association with hyponatremia in the vWD pediatric population [4], the phenomenon can also present suddenly in the adult surgical patient as this case study demonstrates.