Lithium Therapy Workup Protocol
Before initiating lithium therapy, a comprehensive baseline assessment must include renal function, thyroid function, electrolyte tests, urinalysis, and pregnancy testing for women of reproductive age. 1
Initial Baseline Assessment
Laboratory Tests Required Before Starting Lithium:
- Complete blood count
- Renal function tests:
- Blood urea nitrogen (BUN)
- Serum creatinine
- Estimated glomerular filtration rate (eGFR)
- Thyroid function tests:
- Thyroid stimulating hormone (TSH)
- Free T4
- Electrolyte panel:
- Sodium (particularly important due to lithium's interaction with sodium balance)
- Potassium
- Serum calcium
- Urinalysis to assess baseline renal function
- Pregnancy test for females of reproductive potential 1
- Electrocardiogram (ECG) for patients with cardiovascular risk factors or over age 40
Contraindications to Assess
Lithium should generally not be prescribed to patients with:
- Significant renal disease
- Significant cardiovascular disease
- Severe debilitation or dehydration
- Sodium depletion
- Patients receiving diuretics (high risk of lithium toxicity)
- Inability to comply with required monitoring 2
Initial Dosing and Monitoring Schedule
Acute Phase Dosing:
- Start with 300 mg 2-3 times daily
- Optimal response usually established with 600 mg three times daily
- Target serum lithium level: 1.0-1.5 mEq/L for acute mania 2
Acute Phase Monitoring:
- Serum lithium levels: Twice weekly until stabilized
- Blood samples timing: Draw 8-12 hours after the previous dose (trough level) 2
Long-term Maintenance Protocol
Maintenance Dosing:
- Typically 300 mg three or four times daily
- Target serum lithium level: 0.6-1.2 mEq/L 2
Ongoing Monitoring Schedule:
- Serum lithium levels: Every 2 months in uncomplicated cases
- Renal function tests: Every 3-6 months
- Thyroid function tests: Every 3-6 months
- Urinalysis: Every 3-6 months
- Serum calcium: Every 6-12 months 1, 3
Special Considerations
Age-Related Adjustments:
- Elderly patients often require lower doses
- Elderly patients may exhibit toxicity at serum levels normally tolerated by others 2
Gender Considerations:
- Women are at greater risk of developing renal and thyroid disorders
- Younger women (<60 years) are at higher risk than older women 3
Risk Factors for Adverse Effects:
- Higher than median lithium concentrations increase risk of all adverse outcomes
- Longer duration of treatment increases risk of renal dysfunction 3
Warning Signs to Monitor
Signs of Lithium Toxicity:
- Early signs: nausea, diarrhea, blurred vision, polyuria, lightheadedness
- Advanced signs: vomiting, confusion, drowsiness, coarse tremor, muscle twitching
- Severe toxicity: seizures, coma, death
Common Adverse Effects to Monitor:
- Renal: Stage 3 chronic kidney disease (HR 1.93) 3
- Thyroid: Hypothyroidism (HR 2.31) 3
- Parathyroid: Hypercalcemia (HR 1.43) 3
Clinical Pitfalls to Avoid
Inadequate monitoring frequency - Many clinicians fail to check lithium levels, renal function, and thyroid function at recommended intervals 4, 5
Improper sample timing - Blood samples for lithium monitoring must be drawn 12 hours after the evening dose 6
Failure to recognize drug interactions - Particular caution with NSAIDs, ACE inhibitors, diuretics, and sodium-depleting medications
Ignoring early signs of toxicity - Lithium has a narrow therapeutic window requiring vigilant monitoring
Overlooking hydration status - Dehydration can rapidly increase lithium levels to toxic range 7
By following this structured protocol for lithium initiation and monitoring, clinicians can maximize therapeutic benefits while minimizing the well-documented risks to renal, thyroid, and parathyroid function.