All are true of cerebral salt wasting except
**Core Concept**
Cerebral salt wasting (CSW) is a rare condition characterized by excessive loss of sodium and chloride ions in the urine, leading to hyponatremia, despite a low or normal volume status. This condition is often associated with severe brain injury, stroke, or neurosurgical procedures.
**Why the Correct Answer is Right**
Cerebral salt wasting is a complex pathophysiological process involving the release of antidiuretic hormone (ADH) and other factors that stimulate the kidneys to excrete sodium and chloride ions. The condition is characterized by a high urine sodium concentration (>20 mEq/L) and a low serum sodium level (<135 mmol/L), despite a low or normal volume status. The pathophysiology of CSW is not fully understood, but it is thought to involve a disruption in the normal regulation of sodium and water balance in the body.
**Why Each Wrong Option is Incorrect**
**Option A:** This option may be incorrect because CSW is often associated with a low or normal volume status, and excessive fluid administration can worsen the condition.
**Option B:** This option may be incorrect because CSW is characterized by a high urine sodium concentration, not a low urine sodium concentration.
**Option C:** This option may be incorrect because CSW is a distinct clinical entity from the syndrome of inappropriate antidiuretic hormone secretion (SIADH), although both conditions can present with hyponatremia.
**Clinical Pearl / High-Yield Fact**
One key clinical feature of CSW is the presence of a low serum sodium level in the setting of a low or normal volume status, which can be distinguished from SIADH by the presence of a high urine sodium concentration.
**Correct Answer:** A.