**Core Concept**
Hypermagnesemia is a condition characterized by elevated serum magnesium levels, which can lead to neuromuscular and cardiovascular dysfunction. The management of hypermagnesemia involves the use of medications that can either reduce magnesium levels or counteract its effects.

**Why the Correct Answer is Right**
The management of hypermagnesemia typically involves the use of calcium salts (such as calcium gluconate or calcium chloride) to antagonize the effects of excess magnesium on the myocardium and neuromuscular junction. Additionally, loop diuretics (such as furosemide) can be used to enhance renal excretion of magnesium. Hemodialysis may also be necessary in severe cases.

**Why Each Wrong Option is Incorrect**
**Option A:**
This option is incorrect because it is not directly related to the management of hypermagnesemia. While potassium-sparing diuretics may be used in certain conditions, they are not typically used to manage hypermagnesemia.

**Option B:**
This option is incorrect because it is not a standard treatment for hypermagnesemia. While it may have some effects on the cardiovascular system, it is not specifically used to counteract the effects of excess magnesium.

**Option C:**
This option is incorrect because it is actually used to manage hypermagnesemia. Hemodialysis is a treatment option for severe cases of hypermagnesemia that are not responsive to medical management.

**Clinical Pearl / High-Yield Fact**
A key clinical point to remember is that the treatment of hypermagnesemia often involves the use of calcium salts to counteract the effects of excess magnesium on the myocardium and neuromuscular junction. This is a critical concept to remember when managing patients with hypermagnesemia.

**Correct Answer: A. Potassium-sparing diuretics are not used to manage hypermagnesemia.**