Lithium Initiation Blood Draw Schedule
During the acute initiation phase, serum lithium levels should be checked twice per week until levels and clinical condition stabilize, with blood drawn 8-12 hours after the previous dose (typically 12 hours post-dose for standardized monitoring). 1, 2, 3
Baseline Laboratory Assessment (Before Starting Lithium)
Before initiating lithium therapy, obtain the following baseline tests:
- Complete blood count 1, 2
- Thyroid function tests (TSH and free T4) 1, 2
- Renal function tests including blood urea nitrogen, creatinine, and GFR 1, 2
- Serum electrolytes including calcium 1, 2
- Urinalysis 1, 2
These baseline values are essential to identify contraindications such as significant renal impairment (GFR < 60 ml/min/1.73 m²), which requires dose adjustments and more frequent monitoring. 1
Acute Phase Monitoring Schedule
- Check serum lithium levels twice weekly during the acute treatment phase until both serum levels and clinical condition stabilize 1, 2, 3
- Blood sampling timing is critical: Draw blood immediately prior to the next dose, ideally 8-12 hours after the previous dose, when lithium concentrations are relatively stable 3
- Target therapeutic range during acute mania: 1.0-1.5 mEq/L, though toxicity risk begins at 1.5 mEq/L 1, 3
Maintenance Phase Monitoring Schedule
Once a stable lithium dose is achieved:
- Monitor lithium levels every 2 months in uncomplicated cases during maintenance therapy 3
- Monitor renal and thyroid function every 3-6 months 2
- Target maintenance levels: 0.6-1.2 mEq/L 3
Special Populations and Dose Adjustments
Elderly Patients
- Start with lower doses (150 mg/day) due to increased sensitivity and reduced clearance 1
- Elderly patients often exhibit toxicity at serum levels ordinarily tolerated by younger patients 3
Renal Impairment
- GFR < 60 ml/min/1.73 m²: Consider lower doses and more frequent monitoring 1
- GFR < 30 ml/min/1.73 m²: Reduce dose by 50% 1
Lithium Augmentation for Depression
- Lower blood levels (0.2-0.6 mEq/L) may be adequate when lithium is used to augment antidepressants 1
Critical Monitoring Caveats
- Total reliance must not be placed on serum levels alone—accurate patient evaluation requires both clinical and laboratory analysis 3
- Avoid NSAIDs as they can increase lithium levels and risk of toxicity 1
- Maintain adequate hydration, especially during intercurrent illness, as dehydration leads to lithium retention and toxicity 1
- Educate patients about early signs of lithium toxicity to facilitate prompt intervention 2
- Progressive or sudden changes in renal function, even within the normal range, indicate the need for treatment reevaluation 3