Lithium Monitoring Protocols
For patients on lithium therapy, obtain serum lithium levels twice weekly during acute treatment until stabilized, then every 2 months during maintenance therapy, with comprehensive laboratory monitoring every 3-6 months including renal function, thyroid function, and urinalysis. 1, 2
Baseline Laboratory Testing Before Initiating Lithium
Before starting lithium, obtain the following baseline tests 1:
- Complete blood count
- Thyroid function tests (TSH, free T4)
- Renal function tests (BUN, creatinine)
- Serum calcium
- Urinalysis
- Pregnancy test in females of reproductive age
Serum Lithium Level Monitoring Schedule
During Acute Phase
- Draw serum lithium levels twice per week until both the serum level and clinical condition are stabilized 2
- Blood samples should be drawn 8-12 hours after the previous dose (trough level), immediately before the next scheduled dose 2
During Maintenance Phase
- Monitor serum lithium levels at least every 2 months in uncomplicated cases during remission 2
- Continue drawing levels at trough (12 hours post-dose for standard formulations, 24 hours for once-daily dosing) 3
Comprehensive Laboratory Monitoring During Ongoing Treatment
Beyond lithium levels, the American Academy of Child and Adolescent Psychiatry recommends 1:
- Renal function tests every 3-6 months
- Thyroid function tests every 3-6 months
- Urinalysis every 3-6 months
- Serum calcium at least annually
Target Therapeutic Ranges
Acute Mania Treatment
- Target serum lithium: 1.0-1.5 mEq/L (or 0.8-1.0 mmol/L for better tolerability) 2, 4
- The FDA label indicates 1.0-1.5 mEq/L, though modern practice favors 0.7-0.8 mmol/L for acute mania to minimize adverse effects while maintaining efficacy 2, 4
Maintenance/Prophylaxis
- Target serum lithium: 0.6-1.2 mEq/L, with most patients optimally managed at 0.6-0.8 mmol/L 2, 1
- Evidence demonstrates that 0.8-1.0 mmol/L is more effective than 0.4-0.6 mmol/L for preventing relapse, though higher levels cause more side effects 5
Special Population Adjustments
- Elderly patients (≥50 years): target 0.5-0.6 mmol/L 4
- Patients with renal impairment, diabetes insipidus, or thyroid dysfunction: target 0.5-0.6 mmol/L 4
- Patients on diuretics, ACE inhibitors, or NSAIDs: target 0.5-0.6 mmol/L 4
- Bipolar depression prophylaxis: target 0.5-0.6 mmol/L 4
Increased Monitoring Situations
Increase monitoring frequency during 1, 6:
- Intercurrent illness (consider temporarily suspending lithium)
- Planned IV radiocontrast administration
- Bowel preparation procedures
- Prior to major surgery
- Any situation causing dehydration or altered renal function
Recognition of Lithium Toxicity Requiring Immediate Testing
Early signs of lithium toxicity that warrant immediate serum level measurement include 1, 6:
- Tremor (especially coarse tremor)
- Nausea
- Diarrhea
- Polyuria-polydipsia
Patients abnormally sensitive to lithium may exhibit toxic signs at serum levels of 1.0-1.5 mEq/L that are ordinarily therapeutic 2
Critical Clinical Caveat
Total reliance must not be placed on serum levels alone—accurate patient evaluation requires both clinical assessment and laboratory analysis 2. Serum levels do not always correlate with toxicity, particularly in chronic versus acute intoxication, and elderly patients often exhibit toxicity at levels tolerated by younger patients 2, 4.