The therapeutic serum level is narrow (about 0.6-1.2 mEq/L); levels above 1.5 mEq/L are toxic.
Before you read
Test yourself first: 3 questions
Question 1 of 3
A client with bipolar disorder in an acute manic episode is started on lithium, but the nurse knows lithium takes 1 to 2 weeks to work. Which medication is commonly used short-term to control acute manic agitation until the mood stabilizer takes effect?
Answer: A. Because lithium and other mood stabilizers have a delayed onset, an antipsychotic (such as olanzapine, risperidone, or haloperidol) or a benzodiazepine is often used to rapidly control acute manic agitation, psychosis, and sleep disturbance during the lag period. An antidepressant alone could worsen mania.
Question 2 of 3
A client receiving lithium has developed polyuria and increased thirst. The nurse understands this reflects which effect of lithium on the kidneys?
Answer: B. Lithium can interfere with the kidney's response to antidiuretic hormone, causing nephrogenic diabetes insipidus, which produces polyuria and polydipsia. Renal function should be monitored, and the client should maintain adequate hydration.
Question 3 of 3
A client with bipolar disorder is taking lithium carbonate. The nurse reviews a lithium level of 1.0 mEq/L. How should the nurse interpret this result?
Answer: B. The therapeutic maintenance range for lithium is approximately 0.6 to 1.2 mEq/L. A level of 1.0 mEq/L is within the therapeutic range. Levels above 1.5 mEq/L indicate toxicity and require intervention.
Keep the streak going with more questions like these, each with a full rationale.
What is lithium?
It has a very narrow therapeutic range, so blood levels must be monitored closely and toxicity is a constant concern. Memory aid: lithium and sodium 'compete' — low sodium or dehydration raises lithium levels and causes toxicity.
Key points to remember
- The therapeutic serum level is narrow (about 0.6-1.2 mEq/L); levels above 1.5 mEq/L are toxic.
- Sodium and fluid balance directly affect lithium levels: low sodium, dehydration, or diuretics raise lithium and cause toxicity.
- Early toxicity signs include nausea, vomiting, diarrhea, fine tremor, and thirst.
- Worsening toxicity causes coarse tremor, confusion, ataxia, slurred speech, seizures, and cardiac dysrhythmias.
- It can cause hypothyroidism and diabetes insipidus with long-term use, and is teratogenic in pregnancy.
- Therapeutic effect on mania may take 1-3 weeks to develop.
Signs & symptoms
- Early tox: N/V, tremor, diarrhea
- Severe: confusion, ataxia, seizures
Nursing priorities
- Monitor serum lithium levels regularly and report levels at or above 1.5 mEq/L.
- Ensure consistent dietary sodium and adequate fluid intake (about 2-3 liters/day).
- Assess for early signs of toxicity at each contact.
- Monitor thyroid and renal function during long-term therapy.
- Hold the dose and notify the provider for signs of toxicity, dehydration, or illness with vomiting or diarrhea.
Labs & values
Patient teaching
- Maintain a steady salt intake and drink plenty of water; do not crash diet or restrict salt.
- Report vomiting, diarrhea, or excessive sweating because they can cause toxicity.
- Keep all blood-level appointments and learn the early signs of toxicity such as tremor and confusion.
Red flags: report now
- Serum lithium at or above 1.5 mEq/L, or any coarse tremor, confusion, ataxia, or slurred speech.
- Vomiting, diarrhea, fever, or sweating that can cause dehydration and rapidly raise lithium levels.
- Seizures, severe dysrhythmias, or decreasing level of consciousness indicating severe toxicity.
- Starting a sodium-restricted diet or a new diuretic without provider awareness.
References
Clinical references for this topic
