OBJECTIVES: Adult Growth Hormone Deficiency (AGHD) is a poorly understood disease. As a result, treatment patterns and health care access vary by country and misunderstandings regarding the patient reported impacts are common. A well developed PRO measure identifying disease and treatment issues for this population and sensitive to treatment effects is critical for future research and clinical decision making. The purpose of the study was to understand the full spectrum of PRO issues in AGHD and develop a validation ready measure of these impacts. METHODS: :  As the first phase of the PRO measure development process, qualitative data was collected from the literature, experts and patients and transcripts thematically coded according to grounded theory. Based on a synthesis of all information, a conceptual model of the impact of disease and treatment was developed and a PRO measure generated. RESULTS: : 39 AGHD patients (7 focus groups, 3 telephone interviews) and 6 clinical experts in three countries (US, UK, Germany) were interviewed regarding the impact of AGHD and treatment on functioning, well-being and treatment burden. The mean age of patients was 50.7(range 23-82), mean age at diagnosis of 39.7 (range4-71) and 87% were currently on treatment. Across countries common impacts were identified in the domains of Energy, Physical Health, Psychological Health, Cognition and Treatment Burden. A conceptual model of the impacts of AGHD, their consequences and modifiers to the relationship was developed and a 46 item PRO impact measure (TRIM-AGHD) was generated with 5 discrete domains. The TRIM-AGHD was then cognitively debriefed in 9 patients and a validation ready version created. CONCLUSIONS: :  The instrument development process, the full conceptual model, and discussion of clinical implications will be presented. This information should help clinicians identify key PRO issues for AGHD, facilitate targeted treatments and allow for meaningful measurement of treatment effect.