In a patient if administration of exogeneus vasopressin does not increase the osmolality of urine the likely cause is
Answer is C (Renal Hyposensitivity to ADH): Failure of urine osmolality to rise even after administration of exogenous ADH/vasopressin suggests a diagnosis of Nephrogenic Diabetes Insipidus due resistance to action of vasopressin on the Renal tubule (Renal Hyposensitivity to ADH).
SIADH
Psychogenic polydipsia
Renal Hyposensitivity to ADH
ADH Deficiency
Renal Hyposensitivity to ADH