SUN-410 Central Diabetes Insipidus Refractory to Oral Desmopressin (DDAVP)

Background We report a case of CDI due to craniopharyngioma resection that became refractory to oral DDAVP after recurrence of tumor and subsequent surgical removal. Due to inability of patient to use the intranasal route, subcutaneous (SC) DDAVP was used successfully. Clinical Case An 11-year male developed CDI after craniopharyngioma removal and proton beam therapy. He developed also panhypopituitarism, hypothalamic obesity, and had an impaired thirst mechanism. CDI was managed with oral DDAVP and fix fluid intake. After 2 years he had a tumor recurrence and a surgical removal complicated by a stroke. Since then his DDAVP dose had to be increased progressively due to poor CDI control. He presented to our hospital with severe hypernatremia and a urine output of 4-5 liters a day. DDAVP dose was eventually titrated up to 800 mcg bid. He was placed on minimum fluid intake of 3 Liters a day. Even with this dose he was putting out 4 liters of urine daily. Intranasal DDAVP was not considered due to poor cooperation of patient and nasal mucosa scarring. SC DDAVP was started at a dose of 1 mcg (0.01 mcg/Kg) twice a day.Dose increments were made by 0.5 mcg every 2 days to avoid hyponatremia. Prior to therapy patient received 4 liters/day and was progressively decreased, as DDAVP dose was increased, to 1.7 liters/day. Patient was discharged home on 4.5 mcg in the morning and 5.5 mcg at night time (0.14 mcg/kg/day). Discussion The route of administration of DDAVP varies depending on the age and cooperation of the patient to use the different forms available. DDAVP has also haemostatic effect. It is used in the treatment or to prevent bleeding in patients with von Willebrand disease, haemophilia A and platelet function defects. We hypothesize that our patient became resistant to the action of oral DDAVP probably due to the development of antibodies that were interfering with the appropriate absorption from the gastrointestinal tract. The parenteral/SC route dose ranges from 0.1-1 mcg in one or two divided doses nevertheless our patient had a stroke and we were concerned about the maximum dose that it could be used without increasing the risk of causing a new thrombotic event. With no data available about the use of DDAVP in this specific setting, we decided to use as a limit the dose used to treat bleeding disorders (0.3 mcg/Kg).Since our patient had basically an adult weight (70kg) we have enough room to continue increasing the dose up until desire effect was reached keeping in mind that 20 mcg/day is the maximum dose used in adults with bleeding disorders. Since discharge his sodium has remained stable as also his urine output and he has been able to reassume his daily activities. Conclusion: We present a case of CDI refractory to oral DDAVP.SC DDAVP was used and after slow titration patient was able to reach stable sodium levels and urine output with no side effects. Final dose was less than 50% of the dose used to treat bleeding disorders.