Endocrine Abstracts

Introduction: The differential diagnosis between arginine vasopressin deficiency (AVP-D), formally known as central diabetes insipidus, and primary polydipsia (PP) is challenging. In clinical routine, psychopathologic findings are often used as a hallmark for diagnosing PP; thus, it is often referred to as psychogenic polydipsia. Yet, psychopathologic characteristics are barely assessed in patients with AVP-D, and to date, no data exist comparing AVP-D and PP with regard to these features. Therefore, in this study, we aimed to compare levels of anxiety, depression, alexithymia, and overall mental health in patients with AVP-D and PP.

Methods: This study combined data from two diagnostic studies conducted at three tertiary medical centers. In total, 82 participants (n=39 with AVP-D, n=28 with PP, and n=15 healthy controls [HC]) underwent a psychological evaluation with standardized questionnaires at study inclusion. Anxiety levels were assessed using the State-Trait Anxiety Inventory, mood using the Beck’s Depression Inventory, alexithymia using the Toronto Alexithymia Scale, and overall physical and mental health using the Short Form 36 Health Survey (SF-36). Higher STAI, BDI, and TAS scores indicate higher anxiety, depression, and alexithymia levels. Higher SF-36 scores indicate better health and less disability.

Results: Compared with HC, patients with AVP-D and PP showed increased levels of anxiety (HC 28 points [24, 31] vs. AVP-D 36 points [31, 45], P<0.01; vs. PP 38 points [33, 46], P<0.01), depression (HC one point [0, 2] vs. AVP-D 7 points [4, 14], P<0.01; vs. PP 7 points [3, 13], P<0.01), and alexithymia (HC 30 points [29, 37] vs. AVP-D 43 points [35, 54], P<0.01; vs. PP 46 points [37, 55], P<0.01). Levels of anxiety, depression, and alexithymia showed no difference between patients with AVP-D and PP (P=0.58, P=0.90, P=0.50). Compared with HC, patients with AVP-D and PP reported comparable reduced self-reported mental health scores (HC 84 [68, 88] vs. AVP-D 60 [52, 80], P=0.05; vs PP 60 [47, 74], P<0.01).

Conclusion: This is the first study demonstrating comparable increased levels of anxiety, depression, alexithymia, and overall reduced mental health in patients with AVP-D and PP. Based on these data, psychopathological findings should not be used as a hallmark to differentiate between both conditions.