What is the recommended monitoring regime for lithium levels?

The recommended monitoring regime for lithium levels is indeed to check weekly at first and then every three months once the levels are stable. This protocol is established because lithium has a narrow therapeutic index, meaning that the difference between effective and toxic levels is small. During the initiation phase of lithium therapy, frequent monitoring is critical to ensure that serum levels remain within the therapeutic range and to minimize the risk of toxicity.

Initially, lithium levels are monitored weekly to adjust the dosage as needed based on the patient's response and the serum level readings. Once the patient is stabilized and the lithium level has been consistently within the therapeutic range—with no signs of toxicity or adverse effects—the monitoring frequency can be safely reduced to every three months. This ongoing monitoring helps ensure continued efficacy and safety in long-term use.

The other monitoring regimens do not provide the same level of safety and effectiveness. For instance, checking levels every six months might not catch potential toxicity or dose adjustments needed in a timely manner. Monitoring bi-weekly for the first two months does ensure closer observation initially, but it is typically followed by reverting to less frequent monitoring once stability is confirmed, rather than continuing a bi-weekly schedule.