Which of the following statements about Diabetes Insipidus is true –
**Core Concept**
Diabetes Insipidus (DI) is a disorder of the body's ability to regulate fluids, resulting from either a deficiency of antidiuretic hormone (ADH, also known as vasopressin) or the kidneys' inability to respond to ADH.
**Why the Correct Answer is Right**
The correct answer is related to the pathophysiology of DI. ADH plays a crucial role in regulating water reabsorption in the collecting ducts of the kidneys. When ADH is deficient, the kidneys are unable to reabsorb sufficient water, leading to an excessive production of dilute urine. This results in polyuria (excessive urine production) and polydipsia (excessive thirst). In cases of central DI, the deficiency of ADH is due to a lack of production, often resulting from damage to the hypothalamus or pituitary gland. In cases of nephrogenic DI, the kidneys are unresponsive to ADH, leading to a similar clinical presentation.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe the pathophysiology of DI. While hyperglycemia can lead to increased urine production, it is not the primary cause of DI.
**Option B:** This option is incorrect because it is a characteristic of diabetes mellitus, not DI. Hyperglycemia and glycosuria are not typically seen in DI.
**Option C:** This option is incorrect because it does not accurately describe the primary cause of DI. While dehydration can exacerbate the symptoms of DI, it is not the underlying cause of the disorder.
**Clinical Pearl / High-Yield Fact**
In cases of central DI, the administration of desmopressin (a synthetic analogue of ADH) can help to manage symptoms by increasing water reabsorption in the kidneys.
**Correct Answer: C.** This statement is true, as DI is characterized by an excessive production of dilute urine, leading to polyuria and polydipsia.