MON-015 Two Cases of Potential Oral Desmopressin Malabsorption Secondary to Concurrent Tube Feeds Administration in Patients with AVP-D (Arginine Vasopressin Deficiency)

Abstract Disclosure: G. Arora: None. V. Perugu: None. A.T. Drincic: None. Introduction: AVP-D is an endocrine disorder characterized by non-osmotic polyuria, treated with Desmopressin (DDAVP), an AVP analog. Drug resources indicate that food may reduce absorption of oral DDAVP. However, reportedly it does not affect its pharmacodynamics; as such, no precautions are currently advised with food intake or tube feeds. Here, we present two cases where severe polyuria and hypernatremia developed after tube feeds were initiated in patients receiving oral DDAVP, which corrected upon switch to subcutaneous (sq) DDAVP. Case Presentation: Case 1: A 65-year-old female with craniopharyngioma s/p resection and AVP-D on oral DDAVP presented to the emergency department for altered mentation and possible stroke. Na on admission was 141 mmol/L. Subsequently, tube feeds were initiated; and within a day of tube feeds initiation, she developed severe hypernatremia (Na 176 mmol/L, increased from Na 141 mmol/L the day prior) with polyuria, urine output increased to 1.6 ml/kg/hr from 0.5-1 ml/kg/hr on days prior (normal range: 0.5 - 1.5 ml/kg/hr). Oral DDAVP was discontinued and sq DDAVP was initiated with normalization of Na. She remained on tube feeds and was discharged on sq DDAVP, and Na remained normal for weeks with concentrated urine. Case 2: A 19-year-old female with panhypopituitarism and AVP-D on oral DDAVP and G-tube dependence on bolus tube feeds was admitted for hypernatremia - Na 175 mmol/L. Her mother had noted increased urinary output. Medical records indicated that DDAVP was being given with tube feeds. DDAVP was switched to sq. Water balance was restored and Na improved to 141 mmol/L. She was discharged on sq DDAVP, and Na remained normal over the next few months with control of polyuria. Conclusion: We report two cases of non-osmotic polyuria with hypernatremia in patients with AVP-D who received oral DDAVP with tube feeds. We postulate that concurrent administration of tube feeds caused DDAVP malabsorption. The only study evaluating oral DDAVP absorption has shown a 40% reduction when DDAVP is ingested within 90 minutes of a standard meal; however, no effect on pharmacodynamics has been reported. No studies have evaluated oral DDAVP absorption in relation to tube feeds. This becomes even more important in this vulnerable population of patients receiving tube feeds because a majority of them have a concomitantly decreased sense of thirst preventing intake of free water to restore Na-water balance. This warrants further investigation of this phenomenon; and if it holds true, then inclusion of a warning on UptoDate, Micromedex and Lexicom. Until further studies are done, we recommend switching to sq DDAVP dosing in hospitalized patients on tube feeds (especially those with adipsia). Alternative solutions such as increasing oral DDAVP dose and separating oral DDAVP from tube feeds in time - as with Levothyroxine - would need to be studied. Presentation: Monday, July 14, 2025