Guidelines for Initiating Lithium Therapy
When initiating lithium therapy, start with a low dose of 300 mg twice or three times daily and titrate gradually based on serum levels, targeting 0.6-1.2 mEq/L for maintenance therapy, with careful monitoring of renal function and electrolytes. 1
Initial Dosing Strategy
- Start with 300 mg twice daily (600 mg/day) or 300 mg three times daily (900 mg/day) depending on patient age, weight, and renal function 1, 2
- For elderly patients, use lower starting doses (150 mg/day) due to increased sensitivity to lithium and reduced clearance 3, 4
- For acute mania, target serum levels between 1.0-1.5 mEq/L, which can typically be achieved with 600 mg three times daily 1
- For maintenance therapy, target lower serum levels of 0.6-1.2 mEq/L, usually achievable with 300 mg three to four times daily 1, 4
Pre-Initiation Assessment
- Obtain baseline laboratory tests including:
- Complete blood count
- Thyroid function tests (TSH, free T4)
- Renal function (blood urea nitrogen, creatinine, GFR)
- Serum electrolytes including calcium
- Urinalysis
- Pregnancy test for women of childbearing age 3
- Assess for contraindications:
- Significant renal impairment
- Cardiovascular disease
- Severe dehydration
- Sodium depletion
- Concurrent diuretic use 1
Monitoring Schedule
- Measure serum lithium levels twice weekly during acute phase until stabilized 1
- Draw blood samples 12 hours after the last dose (trough level) 1, 4
- For once-daily dosing, measure at 24 hours post-dose 4
- During maintenance therapy, monitor lithium levels every 2 months 1
- Monitor renal function, electrolytes, and lithium levels every 6 months or more frequently if dose changes or patient becomes ill 3
Dosage Adjustments
- Adjust dose based on serum levels and clinical response 1
- For patients with GFR < 60 ml/min/1.73 m², consider lower doses and more frequent monitoring 3
- Reduce dose by 50% in patients with GFR < 30 ml/min/1.73 m² 3
- Consider once-daily dosing to improve tolerability and compliance 5
Special Considerations
- Avoid concomitant use of NSAIDs as they can increase lithium levels and risk of toxicity 3
- Maintain adequate hydration, especially during intercurrent illness 3
- For lithium augmentation of antidepressants, lower doses (300-450 mg/day) may be effective with fewer side effects 6
- Pregnancy requires dose adjustments as lithium clearance increases by 30-50% in the last trimester 4
- For children and adolescents with bipolar disorder, start at 300 mg twice daily and increase by 300 mg weekly based on response and tolerability 2
Signs of Toxicity to Monitor
- Early signs: tremor, nausea, diarrhea, blurred vision, lethargy 4
- Serious toxicity: ataxia, confusion, seizures, coma 4
- Elderly patients may exhibit toxic signs at serum levels normally tolerated by younger patients 1
Formulation Considerations
- Sustained-release formulations have 30-50% lower peak plasma concentrations 4
- With sustained-release preparations, aim for slightly higher serum concentrations (0.8-1.0 mmol/L) compared to standard formulations (0.6-0.8 mmol/L) 4
- Single evening dosing with sustained-release preparations may improve adherence 4, 5
Remember that lithium has a narrow therapeutic index, so careful monitoring is essential to balance efficacy and safety. Regular clinical assessment should accompany laboratory monitoring to ensure optimal treatment outcomes.