**Core Concept**
Cerebral salt wasting (CSW) is a condition characterized by excessive sodium loss in the urine, leading to hyponatremia and hypovolemia, often associated with cerebral disorders such as subarachnoid hemorrhage or traumatic brain injury. The underlying pathophysiology involves impaired renal sodium reabsorption and increased urine sodium excretion.

**Why the Correct Answer is Right**
Low uric acid in serum is not a characteristic feature of cerebral salt wasting. In fact, patients with CSW may have normal or even elevated serum uric acid levels due to the body's compensatory mechanisms to conserve sodium. The other options are true of CSW: increased urine output (A) is a result of the excessive sodium loss, low intravascular volume (B) is a consequence of the sodium and water loss, and decreased vasopressin levels (D) may be observed due to the body's attempt to reduce water reabsorption.

**Why Each Wrong Option is Incorrect**
**Option A:** Increased urine output is a characteristic feature of CSW, as the kidneys excrete excessive amounts of sodium and water.
**Option B:** Low intravascular volume is a direct consequence of the sodium and water loss seen in CSW.
**Option D:** Decreased vasopressin levels may be observed in CSW, as the body attempts to reduce water reabsorption and increase urine output.

**Clinical Pearl / High-Yield Fact**
It's essential to differentiate CSW from the syndrome of inappropriate antidiuretic hormone secretion (SIADH), as both conditions can present with hyponatremia and increased urine sodium. However, in SIADH, serum uric acid levels are often low due to the increased water reabsorption and subsequent dilution of uric acid.

**✓ Correct Answer: C. Low uric acid in serum**