**Core Concept**
Lithium is a commonly used medication for treating bipolar disorder, but its use requires careful consideration before surgery due to its potential to affect bleeding and kidney function. The half-life of lithium is approximately 24 hours, which is crucial in determining the timing of its discontinuation before surgery.

**Why the Correct Answer is Right**
Lithium should be stopped at least 24 hours before surgery to minimize the risk of bleeding complications. Stopping lithium too close to surgery may lead to a rebound effect, which can cause an increased risk of seizures, confusion, and other neurological symptoms. This is because lithium has a long half-life, and its levels may remain elevated for several days after discontinuation. To avoid these complications, it is essential to stop lithium at least 24 hours before surgery to allow its levels to decrease to a safe range.

**Why Each Wrong Option is Incorrect**
**Option A:** Stopping lithium 12 hours before surgery is not sufficient, as its levels may still be elevated, increasing the risk of bleeding complications.
**Option C:** Stopping lithium 48 hours before surgery may be excessive, as its levels will have decreased significantly, but it is still not necessary to discontinue it for 48 hours.
**Option D:** There is no evidence to suggest that stopping lithium 72 hours before surgery is necessary, and this may lead to unnecessary discontinuation of the medication.

**Clinical Pearl / High-Yield Fact**
It is essential to note that not all medications require discontinuation before surgery, and the timing of discontinuation depends on the specific medication and its half-life. A thorough review of the patient's medication list and a discussion with the anesthesiologist or surgeon are crucial in determining the best course of action.

**Correct Answer: C. 48 hours.**