Agreed, overactive-bladder is quite often misdiagnosed. You really have to ask yourself, if your patient has truly “seen a number of different urologists, and has tried nearly every pharmaceutical with no relief”, most likely it’s not really OAB. Also, diabetes insipidus terminology has changed to “Arginine Vasopressin Deficiency” (AVP-D) for central etiologies and “Arginine Vasopressin Resistance” (AVP-R) for nephrogenic etiologies.
Quite a few patients with polyuria can have deficient secretion and/or end-organ effects of the hormone arginine vasopressin. Another visual sign I look foreign this population of patients is increased fine lines on the forehead and around the eyes secondary to dehydration. This is what people get injected with Botox, when the true mechanism is dehydration of the skin, secondary to lack of vasopressin hormone secretion.