**Question:** Lithium levels -+ Normal therapeutic

**Core Concept:** Lithium is a medication primarily used as a mood stabilizer in the treatment of bipolar disorder. It works by modulating the activity of the neurotransmitter systems involved in mood regulation, particularly the serotonin, norepinephrine, and dopamine pathways.

**Why the Correct Answer is Right:**

The correct answer, **Lithium levels 1.5 mEq/L**: This is an example of lithium toxicity, which can lead to serious side effects like tremors, convulsions, impaired renal function, and even death.
B. **Lithium levels > 2 mEq/L**: Like option A, this represents lithium toxicity, causing severe side effects and risking patient safety.
C. **Lithium levels 3 mEq/L**: This is also lithium toxicity, causing severe side effects and potential harm to the patient.

**Clinical Pearl:** Maintaining lithium levels within the therapeutic range is essential for effective treatment of bipolar disorder. Regular monitoring of lithium levels is crucial to ensure optimal therapeutic outcomes and minimize the risk of adverse effects.

**Correct Answer:** **Lithium levels < 0.4 mEq/L** In summary, lithium levels below 0.4 mEq/L are considered subtherapeutic, increasing the risk of relapse in bipolar patients and suggesting the need for dosage adjustment and monitoring.