# A 58-year-old client with bipolar disorder who takes lithium carbonate 900 mg/day and no other psychiatric medications presents with 3 days of vomiting, diarrhea, and poor oral intake. The client reports increased thirst and urination. Vital signs: BP 98/60 mm Hg, HR 110/min, RR 20/min, temperature 37.2°C (99°F). Neurologic examination shows coarse tremor, ataxia, and new confusion; there is no clonus or muscle rigidity. Laboratory results: lithium 2.4 mEq/L (therapeutic 0.6-1.2), sodium 148 mEq/L (135-145), creatinine 1.8 mg/dL (baseline 0.9), BUN 32 mg/dL (7-20). The next scheduled lithium dose is due now. Complete the diagram by selecting the condition the client is most likely experiencing, 2 actions the nurse should take to address that condition, and 2 parameters the nurse should monitor to assess the client's progress.

> source: MyMerci (mymerci.kr)  
> url: https://mymerci.kr/pages/nclex_q.php?qn_id=617433&lang=en  
> language: en  
> subject: Medication Administration  
> category: PPT

## Question

A 58-year-old client with bipolar disorder who takes lithium carbonate 900 mg/day and no other psychiatric medications presents with 3 days of vomiting, diarrhea, and poor oral intake. The client reports increased thirst and urination. Vital signs: BP 98/60 mm Hg, HR 110/min, RR 20/min, temperature 37.2°C (99°F). Neurologic examination shows coarse tremor, ataxia, and new confusion; there is no clonus or muscle rigidity. Laboratory results: lithium 2.4 mEq/L (therapeutic 0.6-1.2), sodium 148 mEq/L (135-145), creatinine 1.8 mg/dL (baseline 0.9), BUN 32 mg/dL (7-20). The next scheduled lithium dose is due now. Complete the diagram by selecting the condition the client is most likely experiencing, 2 actions the nurse should take to address that condition, and 2 parameters the nurse should monitor to assess the client's progress.

Condition

Select 1
Serotonin syndrome
Lithium toxicity with volume depletion and kidney injury
Nephrogenic diabetes insipidus without toxicity
Viral gastroenteritis with dehydration and prerenal azotemia

Actions to take

Select 2
Hold the scheduled lithium dose
Give activated charcoal by mouth
Start IV 0.9% sodium chloride as prescribed
Administer cyproheptadine as prescribed
Encourage oral fluids and recheck in 2 hours

Parameters to monitor

Select 2
Core body temperature
Urine osmolality
Serial serum lithium level
Serum creatine kinase level trend
Serum creatinine and BUN

## Explanation

A lithium level of 2.4 mEq/L with coarse tremor, ataxia, and confusion after volume loss and a doubled creatinine indicates lithium toxicity with acute kidney injury. The nurse holds lithium and starts prescribed IV isotonic saline to restore volume and lithium clearance. Serial lithium levels and creatinine/BUN show whether toxicity and kidney function are improving or whether hemodialysis is needed.

## In-depth explanation

Quick answer
Lithium toxicity with volume depletion and kidney injury; hold lithium and start IV 0.9% sodium chloride as prescribed; monitor serial serum lithium levels and serum creatinine/BUN.

Why this is correct
Lithium is cleared almost entirely by the kidneys and is reabsorbed along with sodium. Vomiting and diarrhea caused sodium and volume loss, reducing lithium clearance and raising the level to 2.4 mEq/L, which now causes neurotoxicity. Isotonic saline restores volume and sodium delivery so the kidneys can excrete lithium, while the next dose is withheld. Falling lithium levels and improving creatinine indicate response; rising levels or worsening renal function prompt consideration of hemodialysis.

Easy analogy or mental picture
Lithium rides the same bus as sodium out through the kidneys. When the body is dry and sodium-starved, the bus stops running and lithium piles up at the station; IV saline restarts the route.

Memory hook
"Dry and salt-poor = lithium soars."

NCLEX decision rule
When a client on lithium has neurologic signs and a high level after fluid loss, withhold the drug, restore volume with isotonic fluid, and trend lithium and renal function.

Why the other choices are wrong
Activated charcoal does not bind lithium. Cyproheptadine treats serotonin syndrome, which is unlikely without a serotonergic drug, hyperthermia, or clonus. Oral fluids are inadequate for a hypotensive, vomiting client with kidney injury. Nephrogenic diabetes insipidus explains the thirst and sodium but not a level of 2.4 mEq/L with cerebellar signs, and gastroenteritis alone does not explain the neurotoxicity. Temperature and creatine kinase track serotonin syndrome or neuroleptic malignant syndrome, and urine osmolality tracks diabetes insipidus rather than lithium clearance.

References
1DailyMed — LithiumLithium toxicity is closely related to serum levels; sodium and fluid depletion and reduced renal function raise levels, and management includes stopping lithium, restoring fluid and electrolyte balance, and monitoring levels.

## Clinical scenario

Scenario
After 3 days of vomiting and diarrhea, a client taking lithium has a level of 2.4 mEq/L with coarse tremor, ataxia, confusion, hypotension, and a doubled creatinine.

## Key concepts

- **Lithium toxicity** — Adverse effects from elevated serum lithium, with coarse tremor, ataxia, and confusion signaling moderate to severe toxicity.
- **Prerenal acute kidney injury** — A fall in kidney function caused by decreased renal blood flow, such as from dehydration.
- **Narrow therapeutic index** — A small difference between therapeutic and toxic drug levels, requiring careful level monitoring.

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