Timing of Serum Lithium Level Recheck
Recheck the serum lithium level in 5-7 days after the last measurement, as the patient is still in the acute stabilization phase having been on lithium for only one week. 1
Rationale for Timing During Acute Phase
The FDA label explicitly states that serum lithium levels should be determined twice per week during the acute phase until both the serum level and clinical condition have been stabilized. 2
The American Academy of Sleep Medicine similarly recommends serum lithium concentrations be determined twice per week during the acute phase until stabilized. 3, 4
Since this patient has been on lithium for only one week with a level checked 2 days ago, they remain in the acute stabilization phase and require continued frequent monitoring. 2
Specific Timing Recommendation
The American Academy of Child and Adolescent Psychiatry specifically recommends rechecking serum lithium levels 5-7 days after dose adjustment, targeting a therapeutic serum concentration of 0.6-0.8 mmol/L for sustained-release preparations. 1
Given that the patient had a normal level 2 days ago, the next check should occur in approximately 5 days (totaling 7 days from the last measurement), which aligns with the twice-weekly monitoring schedule during acute treatment. 1, 2
Important Monitoring Considerations
Blood samples must be drawn 8-12 hours after the previous dose when lithium concentrations are relatively stable (trough levels). 2
For once-daily dosing regimens, serum lithium should be measured at 24 hours post-dose rather than 12 hours to obtain true trough levels, as 12-hour levels can be 1.3 times higher than actual trough levels. 5
Total reliance must not be placed on serum levels alone—accurate patient evaluation requires both clinical and laboratory analysis. 2
Transition to Maintenance Monitoring
Once a stable lithium dose is achieved with consistent therapeutic levels and clinical stability, monitoring frequency can be reduced to every 3-6 months for lithium levels, renal function, and thyroid function. 3, 1
During uncomplicated maintenance therapy, serum lithium levels should be monitored at least every two months. 2