Final answer:
Neurogenic DI is caused by an injury to the neurohypophysial system (posterior pituitary or neurohypophysis) and responds to exogenous ADH administration.
Step-by-step explanation:
Neurogenic diabetes insipidus (DI) is a condition characterized by the inability to concentrate urine due to a deficiency of antidiuretic hormone (ADH), also known as vasopressin.
The neurohypophysial system, comprising the posterior pituitary or neurohypophysis, is responsible for the synthesis and release of ADH. In cases of neurogenic DI, an injury or dysfunction in this system impairs the production or secretion of ADH, leading to excessive urination and thirst. Unlike nephrogenic DI, which results from renal insensitivity to ADH, neurogenic DI can respond positively to exogenous ADH administration.
The injury to the neurohypophysial system may be caused by various factors, including trauma, surgery, tumors, or vascular disorders affecting the posterior pituitary. When administered exogenous ADH (desmopressin), individuals with neurogenic DI typically show a significant improvement in urine concentration.
This positive response to ADH replacement therapy supports the diagnosis of neurogenic DI and helps distinguish it from other causes of polyuria and polydipsia. Management of neurogenic DI involves addressing the underlying cause, when possible, and providing appropriate ADH replacement therapy to alleviate symptoms and maintain fluid balance. Understanding the pathophysiology of neurogenic DI is crucial for healthcare professionals in diagnosing and managing this condition effectively.