**Question:** Cerebral salt-wasting syndrome features include all except

A. Hyperkalemia
B. Hyponatremia
C. Hypokalemia
D. Hyperkalemia

**Core Concept:**
Cerebral salt-wasting syndrome (CSWS) is a rare condition characterized by inappropriate secretion of antidiuretic hormone (ADH) by the pituitary gland. ADH is responsible for reabsorbing sodium and water in the kidneys, and its inappropriate secretion leads to excessive water retention and electrolyte imbalances. In CSWS, the kidneys fail to reabsorb sodium and water, resulting in hyponatremia (low sodium levels), hypokalemia (low potassium levels), and hypochloremia (low chloride levels).

**Why the Correct Answer is Right:**
The correct answer is D. Hyperkalemia, which refers to high potassium levels in the blood. In CSWS, the primary electrolyte imbalances are hyponatremia, hypokalemia, and hypochloremia. Hyperkalemia is not a typical feature of this syndrome but rather occurs in conditions such as renal failure or adrenal insufficiency.

**Why Each Wrong Option is Incorrect:**
A. Hypokalemia: This is one of the key features of CSWS, as potassium levels decrease due to excessive water intake and subsequent osmotic diuresis.
B. Hyponatremia: Similar to hypokalemia, hyponatremia is another typical feature of CSWS due to inappropriate ADH secretion.
C. Hyperkalemia: This is not a feature of CSWS but occurs in conditions like renal failure or adrenal insufficiency.

**Clinical Pearl:**
In CSWS, it is essential to identify the correct electrolyte imbalances and treat them appropriately. Hyperkalemia is not a part of CSWS and should prompt further investigation into alternative causes. A thorough understanding of the syndrome's features is crucial for accurate diagnosis and effective management.