# A client with bipolar disorder has been taking lithium carbonate for 2 weeks. The nurse reviews a trough lithium level drawn 12 hours after the last dose: 0.8 mEq/L. Which action is most appropriate?

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> subject: Medical Emergencies  
> category: PA

## Question

A client with bipolar disorder has been taking lithium carbonate for 2 weeks. The nurse reviews a trough lithium level drawn 12 hours after the last dose: 0.8 mEq/L. Which action is most appropriate?

## Option

1. Hold the lithium and prepare for hemodialysis because the level is toxic.
2. Give sodium polystyrene sulfonate to lower the lithium level.
3. Administer an extra dose because the level is subtherapeutic for acute mania.
4. Continue the prescribed dose and reinforce that the level is within the usual therapeutic range. **✔ Correct answer**

**Correct answer: 4**

## Explanation

A 12-hour trough lithium level of 0.6-1.2 mEq/L is generally therapeutic for maintenance therapy. Toxicity risk rises as levels approach 1.5 mEq/L and above, especially with dehydration or renal impairment. The nurse should continue the current plan and reinforce scheduled monitoring rather than holding or increasing the dose.

## In-depth explanation

Memory Tip Lithium is a narrow-therapeutic-index drug: check a 12-hour trough, monitor renal/thyroid function, and teach hydration and consistent sodium intake.

## Clinical scenario

Scenario Bipolar disorder, lithium 2 weeks, 12-hour trough 0.8 mEq/L.

## Key concepts

- **Lithium therapeutic range** — Maintenance target is usually 0.6-1.2 mEq/L using a 12-hour trough; acute mania targets may be higher by protocol.
- **12-hour trough** — Draw lithium level about 12 hours after the last dose so results are comparable and clinically interpretable.
- **Narrow therapeutic index** — Small changes in renal clearance, sodium, hydration, or interacting drugs can push lithium toward toxicity.

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