Therapeutic Lithium Levels
For acute mania, therapeutic serum lithium levels range from 1.0 to 1.5 mEq/L, while for long-term maintenance therapy, the target is 0.6 to 1.2 mEq/L (or 0.8 to 1.0 mEq/L for optimal relapse prevention). 1
Acute Treatment Phase
- Target serum level: 1.0-1.5 mEq/L for acute mania treatment 1
- Typically achieved with lithium carbonate 600 mg three times daily, though dosing must be adjusted based on individual serum levels 1
- Monitor serum levels twice weekly during the acute phase until both serum concentration and clinical condition stabilize 1, 2
Maintenance Therapy Levels
- Standard therapeutic range: 0.6-1.2 mEq/L for long-term control 1
- Optimal range: 0.8-1.0 mEq/L provides superior relapse prevention compared to lower levels 3
- Usually maintained with 300 mg lithium carbonate three to four times daily 1
Special Dosing Considerations
- Lower therapeutic levels (0.2-0.6 mEq/L) may be adequate when lithium is used to augment antidepressants 4
- Elderly patients often require reduced dosages and may exhibit toxicity at levels normally tolerated by younger patients (1.0-1.5 mEq/L) 1
Toxicity Threshold
- Serum levels ≥1.5 mEq/L represent the lower limit of risk for lithium intoxication 5
- Some patients abnormally sensitive to lithium may exhibit toxic signs at 1.0-1.5 mEq/L 1
- Lithium toxicity is closely related to serum concentrations and can occur at doses close to therapeutic levels 2, 6
Monitoring Requirements
Acute Phase
- Check levels twice weekly until stabilized 1, 2
- Draw blood samples 8-12 hours after the previous dose (standardized 12-hour trough level) 1, 5
Maintenance Phase
- Monitor at least every 2 months for uncomplicated cases in remission 1
- For patients with stable levels in the 0.4-0.79 mEq/L range for 12 months, testing intervals can extend to 6 months 7
- For levels in the 0.8-0.99 mEq/L range, maintain 3-month intervals due to higher risk (10%) of exceeding 1.0 mEq/L 7
- Regular monitoring of clinical state, renal function, and electrolytes is mandatory 2, 4
Critical Safety Considerations
- Never rely solely on serum levels—accurate evaluation requires both clinical assessment and laboratory analysis 1
- Temporarily discontinue lithium in patients with GFR <30 ml/min/1.73 m² during serious intercurrent illness that increases acute kidney injury risk 2, 4
- Avoid NSAIDs as they decrease lithium clearance and increase toxicity risk 4
- Facilities must have access to prompt and accurate serum lithium determination before initiating therapy 2